Merge branch 'eugenp:master' into master

This commit is contained in:
Ulisses Lima 2023-10-13 01:48:04 -03:00 committed by GitHub
commit 24834c5f50
487 changed files with 8533 additions and 1348 deletions

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@ -5,7 +5,7 @@ title: '[ISSUE] '
---
**Article and Module Links**
A link to the affected article and the affected module. The link to the module is the one in the "over on GitHub" standard phrase.
A link to the affected article and the affected module. You can find the link to the module in the Conclusion section in the "on Github" standard phase.
**Describe the Issue**
A clear and concise description of what the issue is.
@ -30,9 +30,3 @@ If applicable, add screenshots to help explain your problem.
**Additional Context**
Add any other context about the issue here.
Note that, unfortunately, we can only help with issues that are specifically and directly related to the article - not with your own, custom application.
StackOverflow is a great place to ask more general questions.
That's primarily because we get a large number of questions and - while we do try to go through as much as everything and help wherever we can, we can't really get back to all of them.

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@ -0,0 +1,102 @@
package com.baeldung.algorithms.rotatearray;
/**
* To speed up the rotation, we narrow k rotations to the remainder of k divided by the array length, or k module the array length.
* Therefore, a large rotation number will be translated into the relative smallest rotation.
* All solutions replace the original array, although they might use an extra array to compute the rotation.
*/
public class RotateArray {
private RotateArray() {
throw new IllegalStateException("Rotate array algorithm utility methods class");
}
/**
*
* @param arr array to apply rotation to
* @param k number of rotations
*/
public static void bruteForce(int[] arr, int k) {
checkInvalidInput(arr, k);
k %= arr.length;
int temp;
int previous;
for (int i = 0; i < k; i++) {
previous = arr[arr.length - 1];
for (int j = 0; j < arr.length; j++) {
temp = arr[j];
arr[j] = previous;
previous = temp;
}
}
}
/**
*
* @param arr array to apply rotation to
* @param k number of rotations
*/
public static void withExtraArray(int[] arr, int k) {
checkInvalidInput(arr, k);
int[] extraArray = new int[arr.length];
for (int i = 0; i < arr.length; i++) {
extraArray[(i + k) % arr.length] = arr[i];
}
System.arraycopy(extraArray, 0, arr, 0, arr.length);
}
/**
*
* @param arr array to apply rotation to
* @param k number of rotations
*/
public static void cyclicReplacement(int[] arr, int k) {
checkInvalidInput(arr, k);
k = k % arr.length;
int count = 0;
for (int start = 0; count < arr.length; start++) {
int current = start;
int prev = arr[start];
do {
int next = (current + k) % arr.length;
int temp = arr[next];
arr[next] = prev;
prev = temp;
current = next;
count++;
} while (start != current);
}
}
/**
*
* @param arr array to apply rotation to
* @param k number of rotations
*/
public static void reverse(int[] arr, int k) {
checkInvalidInput(arr, k);
k %= arr.length;
reverse(arr, 0, arr.length - 1);
reverse(arr, 0, k - 1);
reverse(arr, k, arr.length - 1);
}
private static void reverse(int[] nums, int start, int end) {
while (start < end) {
int temp = nums[start];
nums[start] = nums[end];
nums[end] = temp;
start++;
end--;
}
}
private static void checkInvalidInput(int[] arr, int rotation) {
if (rotation < 1 || arr == null)
throw new IllegalArgumentException("Rotation must be greater than zero or array must be not null");
}
}

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@ -0,0 +1,124 @@
package com.baeldung.algorithms.rotatearray;
import static com.baeldung.algorithms.rotatearray.RotateArray.bruteForce;
import static com.baeldung.algorithms.rotatearray.RotateArray.cyclicReplacement;
import static com.baeldung.algorithms.rotatearray.RotateArray.reverse;
import static com.baeldung.algorithms.rotatearray.RotateArray.withExtraArray;
import static org.junit.jupiter.api.Assertions.assertArrayEquals;
import static org.junit.jupiter.api.Assertions.assertThrows;
import org.junit.jupiter.api.Test;
class RotateArrayUnitTest {
private final int[] arr = { 1, 2, 3, 4, 5, 6 };
private final int rotationLtArrayLength = 1;
private final int rotationGtArrayLength = arr.length + 2;
private final int[] ltArrayLengthRotation = { 6, 1, 2, 3, 4, 5 };
private final int[] gtArrayLengthRotation = { 5, 6, 1, 2, 3, 4 };
@Test
void givenInputArray_whenNoRotationOrEmptyArray_thenThrowIllegalArgumentException() {
final int noRotation = 0;
final int someRotation = arr.length - 1;
assertThrows(IllegalArgumentException.class, () -> bruteForce(arr, noRotation));
assertThrows(IllegalArgumentException.class, () -> withExtraArray(arr, noRotation));
assertThrows(IllegalArgumentException.class, () -> cyclicReplacement(arr, noRotation));
assertThrows(IllegalArgumentException.class, () -> reverse(arr, noRotation));
assertThrows(IllegalArgumentException.class, () -> bruteForce(null, someRotation));
assertThrows(IllegalArgumentException.class, () -> withExtraArray(null, someRotation));
assertThrows(IllegalArgumentException.class, () -> cyclicReplacement(null, someRotation));
assertThrows(IllegalArgumentException.class, () -> reverse(null, someRotation));
}
@Test
void givenInputArray_whenUseBruteForceRotationLtArrayLength_thenRotateArrayOk() {
bruteForce(arr, rotationLtArrayLength);
assertArrayEquals(ltArrayLengthRotation, arr);
}
@Test
void givenInputArray_whenUseBruteForceRotationGtArrayLength_thenRotateArrayOk() {
bruteForce(arr, rotationGtArrayLength);
assertArrayEquals(gtArrayLengthRotation, arr);
}
@Test
void givenInputArray_whenUseBruteForceRotationEqArrayLength_thenDoNothing() {
int[] expected = arr.clone();
bruteForce(arr, arr.length);
assertArrayEquals(expected, arr);
}
@Test
void givenInputArray_whenUseExtraArrayRotationLtArrayLength_thenRotateArrayOk() {
withExtraArray(arr, rotationLtArrayLength);
assertArrayEquals(ltArrayLengthRotation, arr);
}
@Test
void givenInputArray_whenUseExtraArrayRotationGtArrayLength_thenRotateArrayOk() {
withExtraArray(arr, rotationGtArrayLength);
assertArrayEquals(gtArrayLengthRotation, arr);
}
@Test
void givenInputArray_whenUseExtraArrayWithRotationEqArrayLength_thenDoNothing() {
int[] clone = arr.clone();
withExtraArray(arr, arr.length);
assertArrayEquals(clone, arr);
}
@Test
void givenInputArray_whenUseCyclicReplacementRotationLtArrayLength_thenRotateArrayOk() {
cyclicReplacement(arr, rotationLtArrayLength);
assertArrayEquals(ltArrayLengthRotation, arr);
}
@Test
void givenInputArray_whenUseCyclicReplacementRotationGtArrayLength_thenRotateArrayOk() {
cyclicReplacement(arr, rotationGtArrayLength);
assertArrayEquals(gtArrayLengthRotation, arr);
}
@Test
void givenInputArray_whenUseCyclicReplacementRotationEqArrayLength_thenDoNothing() {
int[] clone = arr.clone();
cyclicReplacement(arr, arr.length);
assertArrayEquals(clone, arr);
}
@Test
void givenInputArray_whenUseReverseRotationLtArrayLength_thenRotateArrayOk() {
reverse(arr, rotationLtArrayLength);
assertArrayEquals(ltArrayLengthRotation, arr);
}
@Test
void givenInputArray_whenUseReverseRotationGtArrayLength_thenRotateArrayOk() {
reverse(arr, rotationGtArrayLength);
assertArrayEquals(gtArrayLengthRotation, arr);
}
@Test
void givenInputArray_whenUseReverseRotationEqArrayLength_thenDoNothing() {
int[] clone = arr.clone();
reverse(arr, arr.length);
assertArrayEquals(clone, arr);
}
}

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@ -13,3 +13,4 @@ You can build the project from the command line using: *mvn clean install*, or i
- [Read Data From the Beginning Using Kafka Consumer API](https://www.baeldung.com/java-kafka-consumer-api-read)
- [Get Partition Count for a Topic in Kafka](https://www.baeldung.com/java-kafka-partition-count-topic)
- [bootstrap-server in Kafka Configuration](https://www.baeldung.com/java-kafka-bootstrap-server)
- [Introduction to Apache Kafka](https://www.baeldung.com/apache-kafka)

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@ -0,0 +1,103 @@
package com.baeldung.kafka.multipletopics;
import static org.assertj.core.api.Assertions.assertThat;
import java.time.Duration;
import java.util.Arrays;
import java.util.Properties;
import java.util.concurrent.ExecutionException;
import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.clients.consumer.KafkaConsumer;
import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.ProducerConfig;
import org.apache.kafka.clients.producer.ProducerRecord;
import org.apache.kafka.common.serialization.StringDeserializer;
import org.apache.kafka.common.serialization.StringSerializer;
import org.junit.jupiter.api.AfterAll;
import org.junit.jupiter.api.BeforeAll;
import org.junit.jupiter.api.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.testcontainers.containers.KafkaContainer;
import org.testcontainers.junit.jupiter.Container;
import org.testcontainers.junit.jupiter.Testcontainers;
import org.testcontainers.utility.DockerImageName;
// This live test needs a Docker Daemon running so that a kafka container can be created
@Testcontainers
public class MultipleTopicsLiveTest {
private final Logger log = LoggerFactory.getLogger(MultipleTopicsLiveTest.class);
private static final String CARD_PAYMENTS_TOPIC = "card-payments";
private static final String BANK_TRANSFERS_TOPIC = "bank-transfers";
private static KafkaProducer<String, String> producer;
private static KafkaConsumer<String, String> consumer;
@Container
private static final KafkaContainer KAFKA_CONTAINER = new KafkaContainer(DockerImageName.parse("confluentinc/cp-kafka:latest"));
@BeforeAll
static void setup() {
KAFKA_CONTAINER.addExposedPort(9092);
producer = new KafkaProducer<>(getProducerProperties());
consumer = new KafkaConsumer<>(getConsumerProperties());
}
@AfterAll
static void destroy() {
KAFKA_CONTAINER.stop();
}
private static Properties getProducerProperties() {
Properties producerProperties = new Properties();
producerProperties.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, KAFKA_CONTAINER.getBootstrapServers());
producerProperties.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
producerProperties.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
return producerProperties;
}
private static Properties getConsumerProperties() {
Properties consumerProperties = new Properties();
consumerProperties.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, KAFKA_CONTAINER.getBootstrapServers());
consumerProperties.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
consumerProperties.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
consumerProperties.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
consumerProperties.put(ConsumerConfig.GROUP_ID_CONFIG, "payments");
return consumerProperties;
}
@Test
void whenSendingMessagesOnTwoTopics_thenConsumerReceivesMessages() throws Exception {
publishMessages();
consumer.subscribe(Arrays.asList(CARD_PAYMENTS_TOPIC, BANK_TRANSFERS_TOPIC));
int eventsProcessed = 0;
for (ConsumerRecord<String, String> record : consumer.poll(Duration.ofSeconds(10))) {
log.info("Event on topic={}, payload={}", record.topic(), record.value());
eventsProcessed++;
}
assertThat(eventsProcessed).isEqualTo(2);
}
private void publishMessages() throws ExecutionException, InterruptedException {
ProducerRecord<String, String> cardPayment = new ProducerRecord<>(CARD_PAYMENTS_TOPIC, createCardPayment());
producer.send(cardPayment).get();
ProducerRecord<String, String> bankTransfer = new ProducerRecord<>(BANK_TRANSFERS_TOPIC, createBankTransfer());
producer.send(bankTransfer).get();
}
private String createCardPayment() {
return "{\"paymentReference\":\"A184028KM0013790\", \"type\":\"card\", \"amount\":\"275\", \"currency\":\"GBP\"}";
}
private String createBankTransfer() {
return "{\"paymentReference\":\"19ae2-18mk73-009\", \"type\":\"bank\", \"amount\":\"150\", \"currency\":\"EUR\"}";
}
}

3
apache-poi-3/README.md Normal file
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@ -0,0 +1,3 @@
## Relevant Articles
- [How To Convert Excel Data Into List Of Java Objects](https://www.baeldung.com/java-convert-excel-data-into-list)
- [Expand Columns with Apache POI](https://www.baeldung.com/java-apache-poi-expand-columns)

2
aws-modules/aws-dynamodb/.gitignore vendored Normal file
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@ -0,0 +1,2 @@
/target/
.idea/

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@ -0,0 +1,7 @@
## AWS DYNAMODB
This module contains articles about AWS DynamoDB
### Relevant articles
- [Integration Testing with a Local DynamoDB Instance](https://www.baeldung.com/dynamodb-local-integration-tests)

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@ -0,0 +1,87 @@
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>aws-dynamodb</artifactId>
<version>0.1.0-SNAPSHOT</version>
<name>aws-dynamodb</name>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung</groupId>
<artifactId>aws-modules</artifactId>
<version>1.0.0-SNAPSHOT</version>
</parent>
<dependencies>
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>aws-java-sdk</artifactId>
<version>${aws-java-sdk.version}</version>
</dependency>
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>DynamoDBLocal</artifactId>
<version>${dynamodblocal.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>${commons-io.version}</version>
</dependency>
<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
<version>${gson.version}</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>${maven-shade-plugin.version}</version>
<configuration>
<createDependencyReducedPom>false</createDependencyReducedPom>
</configuration>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<version>${maven-plugins-version}</version>
<executions>
<execution>
<id>copy</id>
<phase>compile</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<includeScope></includeScope>
<includeTypes>so,dll,dylib</includeTypes>
<outputDirectory>native-libs</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
<properties>
<gson.version>2.8.0</gson.version>
<dynamodblocal.version>1.21.1</dynamodblocal.version>
<maven-plugins-version>3.1.1</maven-plugins-version>
</properties>
</project>

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@ -49,10 +49,10 @@ public class ProductInfoRepositoryIntegrationTest {
@BeforeClass
public static void setupClass() {
Properties testProperties = loadFromFileInClasspath("test.properties")
.filter(properties -> !isEmpty(properties.getProperty(AWS_ACCESSKEY)))
.filter(properties -> !isEmpty(properties.getProperty(AWS_SECRETKEY)))
.filter(properties -> !isEmpty(properties.getProperty(DYNAMODB_ENDPOINT)))
.orElseThrow(() -> new RuntimeException("Unable to get all of the required test property values"));
.filter(properties -> !isEmpty(properties.getProperty(AWS_ACCESSKEY)))
.filter(properties -> !isEmpty(properties.getProperty(AWS_SECRETKEY)))
.filter(properties -> !isEmpty(properties.getProperty(DYNAMODB_ENDPOINT)))
.orElseThrow(() -> new RuntimeException("Unable to get all of the required test property values"));
String amazonAWSAccessKey = testProperties.getProperty(AWS_ACCESSKEY);
String amazonAWSSecretKey = testProperties.getProperty(AWS_SECRETKEY);

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@ -16,31 +16,9 @@
<dependencies>
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>aws-java-sdk</artifactId>
<version>${aws-java-sdk.version}</version>
</dependency>
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>aws-lambda-java-core</artifactId>
<version>${aws-lambda-java-core.version}</version>
<exclusions>
<exclusion>
<artifactId>commons-logging</artifactId>
<groupId>commons-logging</groupId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>aws-lambda-java-events</artifactId>
<version>${aws-lambda-java-events.version}</version>
<exclusions>
<exclusion>
<artifactId>commons-logging</artifactId>
<groupId>commons-logging</groupId>
</exclusion>
</exclusions>
<groupId>software.amazon.awssdk</groupId>
<artifactId>aws-sdk-java</artifactId>
<version>${aws-java-sdk-v2.version}</version>
</dependency>
<dependency>
<groupId>commons-io</groupId>
@ -52,12 +30,6 @@
<artifactId>gson</artifactId>
<version>${gson.version}</version>
</dependency>
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>DynamoDBLocal</artifactId>
<version>${dynamodblocal.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
@ -101,8 +73,6 @@
</build>
<properties>
<aws-lambda-java-events.version>1.3.0</aws-lambda-java-events.version>
<aws-lambda-java-core.version>1.1.0</aws-lambda-java-core.version>
<gson.version>2.8.0</gson.version>
<dynamodblocal.version>1.21.1</dynamodblocal.version>
<commons-codec-version>1.10.L001</commons-codec-version>

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@ -2,136 +2,148 @@ package com.baeldung.ec2;
import java.util.Arrays;
import com.amazonaws.auth.AWSCredentials;
import com.amazonaws.auth.AWSStaticCredentialsProvider;
import com.amazonaws.auth.BasicAWSCredentials;
import com.amazonaws.regions.Regions;
import com.amazonaws.services.ec2.AmazonEC2;
import com.amazonaws.services.ec2.AmazonEC2ClientBuilder;
import com.amazonaws.services.ec2.model.AuthorizeSecurityGroupIngressRequest;
import com.amazonaws.services.ec2.model.CreateKeyPairRequest;
import com.amazonaws.services.ec2.model.CreateKeyPairResult;
import com.amazonaws.services.ec2.model.CreateSecurityGroupRequest;
import com.amazonaws.services.ec2.model.DescribeInstancesRequest;
import com.amazonaws.services.ec2.model.DescribeInstancesResult;
import com.amazonaws.services.ec2.model.DescribeKeyPairsRequest;
import com.amazonaws.services.ec2.model.DescribeKeyPairsResult;
import com.amazonaws.services.ec2.model.IpPermission;
import com.amazonaws.services.ec2.model.IpRange;
import com.amazonaws.services.ec2.model.MonitorInstancesRequest;
import com.amazonaws.services.ec2.model.RebootInstancesRequest;
import com.amazonaws.services.ec2.model.RunInstancesRequest;
import com.amazonaws.services.ec2.model.StartInstancesRequest;
import com.amazonaws.services.ec2.model.StopInstancesRequest;
import com.amazonaws.services.ec2.model.UnmonitorInstancesRequest;
import software.amazon.awssdk.auth.credentials.ProfileCredentialsProvider;
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.ec2.Ec2Client;
import software.amazon.awssdk.services.ec2.model.AuthorizeSecurityGroupIngressRequest;
import software.amazon.awssdk.services.ec2.model.CreateKeyPairRequest;
import software.amazon.awssdk.services.ec2.model.CreateKeyPairResponse;
import software.amazon.awssdk.services.ec2.model.CreateSecurityGroupRequest;
import software.amazon.awssdk.services.ec2.model.DescribeInstancesRequest;
import software.amazon.awssdk.services.ec2.model.DescribeInstancesResponse;
import software.amazon.awssdk.services.ec2.model.DescribeKeyPairsRequest;
import software.amazon.awssdk.services.ec2.model.DescribeKeyPairsResponse;
import software.amazon.awssdk.services.ec2.model.IpPermission;
import software.amazon.awssdk.services.ec2.model.IpRange;
import software.amazon.awssdk.services.ec2.model.MonitorInstancesRequest;
import software.amazon.awssdk.services.ec2.model.RebootInstancesRequest;
import software.amazon.awssdk.services.ec2.model.RunInstancesRequest;
import software.amazon.awssdk.services.ec2.model.RunInstancesResponse;
import software.amazon.awssdk.services.ec2.model.StartInstancesRequest;
import software.amazon.awssdk.services.ec2.model.StartInstancesResponse;
import software.amazon.awssdk.services.ec2.model.StopInstancesRequest;
import software.amazon.awssdk.services.ec2.model.UnmonitorInstancesRequest;
public class EC2Application {
private static final AWSCredentials credentials;
static {
// put your accesskey and secretkey here
credentials = new BasicAWSCredentials(
"<AWS accesskey>",
"<AWS secretkey>"
);
}
public static void main(String[] args) {
// Set up the client
AmazonEC2 ec2Client = AmazonEC2ClientBuilder.standard()
.withCredentials(new AWSStaticCredentialsProvider(credentials))
.withRegion(Regions.US_EAST_1)
Ec2Client ec2Client = Ec2Client.builder()
.credentialsProvider(ProfileCredentialsProvider.create("default"))
.region(Region.US_EAST_1)
.build();
// Create a security group
CreateSecurityGroupRequest createSecurityGroupRequest = new CreateSecurityGroupRequest().withGroupName("BaeldungSecurityGroup")
.withDescription("Baeldung Security Group");
CreateSecurityGroupRequest createSecurityGroupRequest = CreateSecurityGroupRequest.builder()
.groupName("BaeldungSecurityGroup")
.description("Baeldung Security Group")
.build();
ec2Client.createSecurityGroup(createSecurityGroupRequest);
// Allow HTTP and SSH traffic
IpRange ipRange1 = new IpRange().withCidrIp("0.0.0.0/0");
IpRange ipRange1 = IpRange.builder()
.cidrIp("0.0.0.0/0")
.build();
IpPermission ipPermission1 = new IpPermission().withIpv4Ranges(Arrays.asList(new IpRange[] { ipRange1 }))
.withIpProtocol("tcp")
.withFromPort(80)
.withToPort(80);
IpPermission ipPermission1 = IpPermission.builder()
.ipRanges(Arrays.asList(ipRange1))
.ipProtocol("tcp")
.fromPort(80)
.toPort(80)
.build();
IpPermission ipPermission2 = new IpPermission().withIpv4Ranges(Arrays.asList(new IpRange[] { ipRange1 }))
.withIpProtocol("tcp")
.withFromPort(22)
.withToPort(22);
IpPermission ipPermission2 = IpPermission.builder()
.ipRanges(Arrays.asList(ipRange1))
.ipProtocol("tcp")
.fromPort(22)
.toPort(22)
.build();
AuthorizeSecurityGroupIngressRequest authorizeSecurityGroupIngressRequest = new AuthorizeSecurityGroupIngressRequest()
.withGroupName("BaeldungSecurityGroup")
.withIpPermissions(ipPermission1, ipPermission2);
AuthorizeSecurityGroupIngressRequest authorizeSecurityGroupIngressRequest = AuthorizeSecurityGroupIngressRequest
.builder()
.groupName("BaeldungSecurityGroup")
.ipPermissions(ipPermission1, ipPermission2)
.build();
ec2Client.authorizeSecurityGroupIngress(authorizeSecurityGroupIngressRequest);
// Create KeyPair
CreateKeyPairRequest createKeyPairRequest = new CreateKeyPairRequest()
.withKeyName("baeldung-key-pair");
CreateKeyPairResult createKeyPairResult = ec2Client.createKeyPair(createKeyPairRequest);
String privateKey = createKeyPairResult
.getKeyPair()
.getKeyMaterial(); // make sure you keep it, the private key, Amazon doesn't store the private key
CreateKeyPairRequest createKeyPairRequest = CreateKeyPairRequest.builder()
.keyName("baeldung-key-pair")
.build();
CreateKeyPairResponse createKeyPairResponse = ec2Client.createKeyPair(createKeyPairRequest);
String privateKey = createKeyPairResponse.keyMaterial();
// make sure you keep it, the private key, Amazon doesn't store the private key
// See what key-pairs you've got
DescribeKeyPairsRequest describeKeyPairsRequest = new DescribeKeyPairsRequest();
DescribeKeyPairsResult describeKeyPairsResult = ec2Client.describeKeyPairs(describeKeyPairsRequest);
DescribeKeyPairsRequest describeKeyPairsRequest = DescribeKeyPairsRequest.builder()
.build();
DescribeKeyPairsResponse describeKeyPairsResponse = ec2Client.describeKeyPairs(describeKeyPairsRequest);
// Launch an Amazon Instance
RunInstancesRequest runInstancesRequest = new RunInstancesRequest().withImageId("ami-97785bed") // https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/AMIs.html | https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/usingsharedamis-finding.html
.withInstanceType("t2.micro") // https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instance-types.html
.withMinCount(1)
.withMaxCount(1)
.withKeyName("baeldung-key-pair") // optional - if not present, can't connect to instance
.withSecurityGroups("BaeldungSecurityGroup");
RunInstancesRequest runInstancesRequest = RunInstancesRequest.builder()
.imageId("ami-97785bed")
.instanceType("t2.micro") // https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instance-types.html
.minCount(1)
.maxCount(1)
.keyName("baeldung-key-pair") // optional - if not present, can't connect to instance
.securityGroups("BaeldungSecurityGroup")
.build();
String yourInstanceId = ec2Client.runInstances(runInstancesRequest).getReservation().getInstances().get(0).getInstanceId();
RunInstancesResponse runInstancesResponse = ec2Client.runInstances(runInstancesRequest);
String yourInstanceId = runInstancesResponse.instances().get(0).instanceId();
// Start an Instance
StartInstancesRequest startInstancesRequest = new StartInstancesRequest()
.withInstanceIds(yourInstanceId);
StartInstancesRequest startInstancesRequest = StartInstancesRequest.builder()
.instanceIds(yourInstanceId)
.build();
StartInstancesResponse startInstancesResponse = ec2Client.startInstances(startInstancesRequest);
ec2Client.startInstances(startInstancesRequest);
// Monitor Instances
MonitorInstancesRequest monitorInstancesRequest = new MonitorInstancesRequest()
.withInstanceIds(yourInstanceId);
MonitorInstancesRequest monitorInstancesRequest = MonitorInstancesRequest.builder()
.instanceIds(yourInstanceId)
.build();
ec2Client.monitorInstances(monitorInstancesRequest);
UnmonitorInstancesRequest unmonitorInstancesRequest = new UnmonitorInstancesRequest()
.withInstanceIds(yourInstanceId);
UnmonitorInstancesRequest unmonitorInstancesRequest = UnmonitorInstancesRequest.builder()
.instanceIds(yourInstanceId)
.build();
ec2Client.unmonitorInstances(unmonitorInstancesRequest);
// Reboot an Instance
RebootInstancesRequest rebootInstancesRequest = new RebootInstancesRequest()
.withInstanceIds(yourInstanceId);
RebootInstancesRequest rebootInstancesRequest = RebootInstancesRequest.builder()
.instanceIds(yourInstanceId)
.build();
ec2Client.rebootInstances(rebootInstancesRequest);
// Stop an Instance
StopInstancesRequest stopInstancesRequest = new StopInstancesRequest()
.withInstanceIds(yourInstanceId);
StopInstancesRequest stopInstancesRequest = StopInstancesRequest.builder()
.instanceIds(yourInstanceId)
.build();
ec2Client.stopInstances(stopInstancesRequest)
.getStoppingInstances()
.stoppingInstances()
.get(0)
.getPreviousState()
.getName();
.previousState()
.name();
// Describe an Instance
DescribeInstancesRequest describeInstancesRequest = new DescribeInstancesRequest();
DescribeInstancesResult response = ec2Client.describeInstances(describeInstancesRequest);
System.out.println(response.getReservations()
DescribeInstancesRequest describeInstancesRequest = DescribeInstancesRequest.builder().build();
DescribeInstancesResponse response = ec2Client.describeInstances(describeInstancesRequest);
System.out.println(response.reservations()
.get(0)
.getInstances()
.instances()
.get(0)
.getKernelId());
.kernelId());
}
}

View File

@ -1,13 +1,5 @@
package com.baeldung.rds;
import com.amazonaws.auth.AWSCredentialsProvider;
import com.amazonaws.auth.AWSStaticCredentialsProvider;
import com.amazonaws.auth.BasicAWSCredentials;
import com.amazonaws.regions.Regions;
import com.amazonaws.services.rds.AmazonRDS;
import com.amazonaws.services.rds.AmazonRDSClientBuilder;
import com.amazonaws.services.rds.model.*;
import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
@ -16,12 +8,22 @@ import java.util.Properties;
import java.util.UUID;
import java.util.logging.Logger;
import software.amazon.awssdk.auth.credentials.ProfileCredentialsProvider;
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.rds.RdsClient;
import software.amazon.awssdk.services.rds.model.CreateDbInstanceRequest;
import software.amazon.awssdk.services.rds.model.CreateDbInstanceResponse;
import software.amazon.awssdk.services.rds.model.DBInstance;
import software.amazon.awssdk.services.rds.model.DeleteDbInstanceRequest;
import software.amazon.awssdk.services.rds.model.DeleteDbInstanceResponse;
import software.amazon.awssdk.services.rds.model.DescribeDbInstancesResponse;
import software.amazon.awssdk.services.rds.model.Endpoint;
public class AWSRDSService {
final static Logger logger = Logger.getLogger(AWSRDSService.class.getName());
private AWSCredentialsProvider credentials;
private AmazonRDS amazonRDS;
private RdsClient rdsClient;
private String db_username;
private String db_password;
private String db_database;
@ -34,22 +36,17 @@ public class AWSRDSService {
* **/
public AWSRDSService() throws IOException {
//Init RDS client with credentials and region.
credentials = new
AWSStaticCredentialsProvider(new
BasicAWSCredentials("<ACCESS_KEY>",
"<SECRET_KEY>"));
amazonRDS = AmazonRDSClientBuilder.standard().withCredentials(credentials)
.withRegion(Regions.AP_SOUTHEAST_2).build();
Properties prop = new Properties();
InputStream input = AWSRDSService.class.getClassLoader().getResourceAsStream("db.properties");
prop.load(input);
db_username = prop.getProperty("db_username");
db_password = prop.getProperty("db_password");
db_database = prop.getProperty("db_database");
}
public AWSRDSService(AmazonRDS amazonRDS){
this.amazonRDS = amazonRDS;
rdsClient = RdsClient.builder()
.region(Region.AP_SOUTHEAST_2)
.credentialsProvider(ProfileCredentialsProvider.create("default"))
.build();
}
/**
@ -60,29 +57,29 @@ public class AWSRDSService {
public String launchInstance() {
String identifier = "";
CreateDBInstanceRequest request = new CreateDBInstanceRequest();
// RDS instance name
request.setDBInstanceIdentifier("Sydney");
request.setEngine("postgres");
request.setMultiAZ(false);
request.setMasterUsername(db_username);
request.setMasterUserPassword(db_password);
request.setDBName(db_database);
request.setStorageType("gp2");
request.setAllocatedStorage(10);
CreateDbInstanceRequest instanceRequest = CreateDbInstanceRequest.builder()
.dbInstanceIdentifier("Sydney")
.engine("postgres")
.multiAZ(false)
.masterUsername(db_username)
.masterUserPassword(db_password)
.dbName(db_database)
.storageType("gp2")
.allocatedStorage(10)
.build();
DBInstance instance = amazonRDS.createDBInstance(request);
CreateDbInstanceResponse createDbInstanceResponse = rdsClient.createDBInstance(instanceRequest);
// Information about the new RDS instance
identifier = instance.getDBInstanceIdentifier();
String status = instance.getDBInstanceStatus();
Endpoint endpoint = instance.getEndpoint();
String endpoint_url = "Endpoint URL not available yet.";
identifier = createDbInstanceResponse.dbInstance().dbInstanceIdentifier();
String status = createDbInstanceResponse.dbInstance().dbInstanceStatus();
Endpoint endpoint = createDbInstanceResponse.dbInstance().endpoint();
String endpointUrl = "Endpoint URL not available yet.";
if (endpoint != null) {
endpoint_url = endpoint.toString();
endpointUrl = endpoint.toString();
}
logger.info(identifier + "\t" + status);
logger.info(endpoint_url);
logger.info(endpointUrl);
return identifier;
@ -90,44 +87,44 @@ public class AWSRDSService {
// Describe DB instances
public void listInstances() {
DescribeDBInstancesResult result = amazonRDS.describeDBInstances();
List<DBInstance> instances = result.getDBInstances();
DescribeDbInstancesResponse response = rdsClient.describeDBInstances();
List<DBInstance> instances = response.dbInstances();
for (DBInstance instance : instances) {
// Information about each RDS instance
String identifier = instance.getDBInstanceIdentifier();
String engine = instance.getEngine();
String status = instance.getDBInstanceStatus();
Endpoint endpoint = instance.getEndpoint();
String endpoint_url = "Endpoint URL not available yet.";
String identifier = instance.dbInstanceIdentifier();
String engine = instance.engine();
String status = instance.dbInstanceStatus();
Endpoint endpoint = instance.endpoint();
String endpointUrl = "Endpoint URL not available yet.";
if (endpoint != null) {
endpoint_url = endpoint.toString();
endpointUrl = endpoint.toString();
}
logger.info(identifier + "\t" + engine + "\t" + status);
logger.info("\t" + endpoint_url);
logger.info("\t" + endpointUrl);
}
}
//Delete RDS instance
public void terminateInstance(String identifier) {
DeleteDBInstanceRequest request = new DeleteDBInstanceRequest();
request.setDBInstanceIdentifier(identifier);
request.setSkipFinalSnapshot(true);
DeleteDbInstanceRequest request = DeleteDbInstanceRequest.builder()
.dbInstanceIdentifier(identifier)
.skipFinalSnapshot(true)
.build();
// Delete the RDS instance
DBInstance instance = amazonRDS.deleteDBInstance(request);
DeleteDbInstanceResponse response = rdsClient.deleteDBInstance(request);
// Information about the RDS instance being deleted
String status = instance.getDBInstanceStatus();
Endpoint endpoint = instance.getEndpoint();
String endpoint_url = "Endpoint URL not available yet.";
String status = response.dbInstance().dbInstanceStatus();
Endpoint endpoint = response.dbInstance().endpoint();
String endpointUrl = "Endpoint URL not available yet.";
if (endpoint != null) {
endpoint_url = endpoint.toString();
endpointUrl = endpoint.toString();
}
logger.info(identifier + "\t" + status);
logger.info(endpoint_url);
logger.info(endpointUrl);
}

View File

@ -5,140 +5,190 @@ import java.util.HashMap;
import java.util.List;
import java.util.Map;
import com.amazonaws.auth.AWSCredentials;
import com.amazonaws.auth.AWSStaticCredentialsProvider;
import com.amazonaws.auth.BasicAWSCredentials;
import com.amazonaws.regions.Regions;
import com.amazonaws.services.sqs.AmazonSQSClientBuilder;
import com.amazonaws.services.sqs.model.CreateQueueRequest;
import com.amazonaws.services.sqs.model.DeleteMessageRequest;
import com.amazonaws.services.sqs.model.GetQueueAttributesRequest;
import com.amazonaws.services.sqs.model.GetQueueAttributesResult;
import com.amazonaws.services.sqs.model.MessageAttributeValue;
import com.amazonaws.services.sqs.model.ReceiveMessageRequest;
import com.amazonaws.services.sqs.model.SendMessageBatchRequest;
import com.amazonaws.services.sqs.model.SendMessageRequest;
import com.amazonaws.services.sqs.model.SetQueueAttributesRequest;
import com.amazonaws.services.sqs.model.SendMessageBatchRequestEntry;
import com.amazonaws.services.sqs.model.Message;
import com.amazonaws.services.sqs.AmazonSQS;
import software.amazon.awssdk.auth.credentials.ProfileCredentialsProvider;
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.sqs.SqsClient;
import software.amazon.awssdk.services.sqs.model.CreateQueueRequest;
import software.amazon.awssdk.services.sqs.model.DeleteMessageRequest;
import software.amazon.awssdk.services.sqs.model.GetQueueAttributesRequest;
import software.amazon.awssdk.services.sqs.model.GetQueueAttributesResponse;
import software.amazon.awssdk.services.sqs.model.GetQueueUrlRequest;
import software.amazon.awssdk.services.sqs.model.GetQueueUrlResponse;
import software.amazon.awssdk.services.sqs.model.Message;
import software.amazon.awssdk.services.sqs.model.MessageAttributeValue;
import software.amazon.awssdk.services.sqs.model.QueueAttributeName;
import software.amazon.awssdk.services.sqs.model.ReceiveMessageRequest;
import software.amazon.awssdk.services.sqs.model.SendMessageBatchRequest;
import software.amazon.awssdk.services.sqs.model.SendMessageBatchRequestEntry;
import software.amazon.awssdk.services.sqs.model.SendMessageRequest;
import software.amazon.awssdk.services.sqs.model.SetQueueAttributesRequest;
public class SQSApplication {
private static final AWSCredentials credentials;
static {
// put your accesskey and secretkey here
credentials = new BasicAWSCredentials(
"<AWS accesskey>",
"<AWS secretkey>"
);
}
private static final String STANDARD_QUEUE_NAME = "baeldung-queue";
private static final String FIFO_QUEUE_NAME = "baeldung-queue.fifo";
private static final String DEAD_LETTER_QUEUE_NAME = "baeldung-dead-letter-queue";
public static void main(String[] args) {
// Set up the client
AmazonSQS sqs = AmazonSQSClientBuilder.standard()
.withCredentials(new AWSStaticCredentialsProvider(credentials))
.withRegion(Regions.US_EAST_1)
SqsClient sqsClient = SqsClient.builder()
.region(Region.US_EAST_1)
.credentialsProvider(ProfileCredentialsProvider.create())
.build();
// Create a standard queue
CreateQueueRequest createStandardQueueRequest = CreateQueueRequest.builder()
.queueName(STANDARD_QUEUE_NAME)
.build();
CreateQueueRequest createStandardQueueRequest = new CreateQueueRequest("baeldung-queue");
String standardQueueUrl = sqs.createQueue(createStandardQueueRequest)
.getQueueUrl();
sqsClient.createQueue(createStandardQueueRequest);
System.out.println("\nGet queue url");
GetQueueUrlResponse getQueueUrlResponse = sqsClient.getQueueUrl(GetQueueUrlRequest.builder()
.queueName(STANDARD_QUEUE_NAME)
.build());
String standardQueueUrl = getQueueUrlResponse.queueUrl();
System.out.println(standardQueueUrl);
// Create a fifo queue
Map<QueueAttributeName, String> queueAttributes = new HashMap<>();
queueAttributes.put(QueueAttributeName.FIFO_QUEUE, "true");
queueAttributes.put(QueueAttributeName.CONTENT_BASED_DEDUPLICATION, "true");
Map<String, String> queueAttributes = new HashMap<String, String>();
queueAttributes.put("FifoQueue", "true");
queueAttributes.put("ContentBasedDeduplication", "true");
CreateQueueRequest createFifoQueueRequest = CreateQueueRequest.builder()
.queueName(FIFO_QUEUE_NAME)
.attributes(queueAttributes)
.build();
CreateQueueRequest createFifoQueueRequest = new CreateQueueRequest("baeldung-queue.fifo").withAttributes(queueAttributes);
String fifoQueueUrl = sqs.createQueue(createFifoQueueRequest)
.getQueueUrl();
sqsClient.createQueue(createFifoQueueRequest);
GetQueueUrlResponse getFifoQueueUrlResponse = sqsClient.getQueueUrl(GetQueueUrlRequest.builder()
.queueName(FIFO_QUEUE_NAME)
.build());
String fifoQueueUrl = getFifoQueueUrlResponse.queueUrl();
System.out.println(fifoQueueUrl);
// Set up a dead letter queue
CreateQueueRequest createDeadLetterQueueRequest = CreateQueueRequest.builder()
.queueName(DEAD_LETTER_QUEUE_NAME)
.build();
String deadLetterQueueUrl = sqs.createQueue("baeldung-dead-letter-queue")
.getQueueUrl();
String deadLetterQueueUrl = sqsClient.createQueue(createDeadLetterQueueRequest)
.queueUrl();
GetQueueAttributesResult deadLetterQueueAttributes = sqs.getQueueAttributes(new GetQueueAttributesRequest(deadLetterQueueUrl).withAttributeNames("QueueArn"));
GetQueueAttributesRequest getQueueAttributesRequest = GetQueueAttributesRequest.builder()
.queueUrl(deadLetterQueueUrl)
.attributeNames(QueueAttributeName.QUEUE_ARN)
.build();
String deadLetterQueueARN = deadLetterQueueAttributes.getAttributes()
GetQueueAttributesResponse deadLetterQueueAttributes = sqsClient.getQueueAttributes(getQueueAttributesRequest);
String deadLetterQueueARN = deadLetterQueueAttributes.attributes()
.get("QueueArn");
SetQueueAttributesRequest queueAttributesRequest = new SetQueueAttributesRequest().withQueueUrl(standardQueueUrl)
.addAttributesEntry("RedrivePolicy", "{\"maxReceiveCount\":\"2\", " + "\"deadLetterTargetArn\":\"" + deadLetterQueueARN + "\"}");
Map<QueueAttributeName, String> attributes = new HashMap<>();
attributes.put(QueueAttributeName.REDRIVE_POLICY, "{\"maxReceiveCount\":\"5\", \"deadLetterTargetArn\":\"" + deadLetterQueueARN + "\"}");
sqs.setQueueAttributes(queueAttributesRequest);
SetQueueAttributesRequest queueAttributesRequest = SetQueueAttributesRequest.builder()
.queueUrl(standardQueueUrl)
.attributes(attributes)
.build();
sqsClient.setQueueAttributes(queueAttributesRequest);
// Send a message to a standard queue
Map<String, MessageAttributeValue> messageAttributes = new HashMap<>();
MessageAttributeValue messageAttributeValue = MessageAttributeValue.builder()
.stringValue("This is an attribute")
.dataType("String")
.build();
messageAttributes.put("AttributeOne", new MessageAttributeValue().withStringValue("This is an attribute")
.withDataType("String"));
messageAttributes.put("AttributeOne", messageAttributeValue);
SendMessageRequest sendMessageStandardQueue = new SendMessageRequest().withQueueUrl(standardQueueUrl)
.withMessageBody("A simple message.")
.withDelaySeconds(30) // Message will arrive in the queue after 30 seconds. We can use this only in standard queues
.withMessageAttributes(messageAttributes);
SendMessageRequest sendMessageStandardQueue = SendMessageRequest.builder()
.queueUrl(standardQueueUrl)
.messageBody("A simple message.")
.delaySeconds(30) // Message will arrive in the queue after 30 seconds. We can use this only in standard queues
.messageAttributes(messageAttributes)
.build();
sqs.sendMessage(sendMessageStandardQueue);
sqsClient.sendMessage(sendMessageStandardQueue);
// Send a message to a fifo queue
SendMessageRequest sendMessageFifoQueue = new SendMessageRequest().withQueueUrl(fifoQueueUrl)
.withMessageBody("FIFO Queue")
.withMessageGroupId("baeldung-group-1")
.withMessageAttributes(messageAttributes);
SendMessageRequest sendMessageFifoQueue = SendMessageRequest.builder()
.queueUrl(fifoQueueUrl)
.messageBody("FIFO Queue")
.messageGroupId("baeldung-group-1")
.messageAttributes(messageAttributes)
.build();
sqs.sendMessage(sendMessageFifoQueue);
sqsClient.sendMessage(sendMessageFifoQueue);
// Send multiple messages
List<SendMessageBatchRequestEntry> messageEntries = new ArrayList<>();
messageEntries.add(new SendMessageBatchRequestEntry().withId("id-1")
.withMessageBody("batch-1")
.withMessageGroupId("baeldung-group-1"));
messageEntries.add(new SendMessageBatchRequestEntry().withId("id-2")
.withMessageBody("batch-2")
.withMessageGroupId("baeldung-group-1"));
SendMessageBatchRequestEntry messageBatchRequestEntry1 = SendMessageBatchRequestEntry.builder()
.id("id-1")
.messageBody("batch-1")
.messageGroupId("baeldung-group-1")
.build();
SendMessageBatchRequest sendMessageBatchRequest = new SendMessageBatchRequest(fifoQueueUrl, messageEntries);
sqs.sendMessageBatch(sendMessageBatchRequest);
SendMessageBatchRequestEntry messageBatchRequestEntry2 = SendMessageBatchRequestEntry.builder()
.id("id-2")
.messageBody("batch-2")
.messageGroupId("baeldung-group-1")
.build();
messageEntries.add(messageBatchRequestEntry1);
messageEntries.add(messageBatchRequestEntry2);
SendMessageBatchRequest sendMessageBatchRequest = SendMessageBatchRequest.builder()
.queueUrl(fifoQueueUrl)
.entries(messageEntries)
.build();
sqsClient.sendMessageBatch(sendMessageBatchRequest);
// Read a message from a queue
ReceiveMessageRequest receiveMessageRequest = new ReceiveMessageRequest(fifoQueueUrl).withWaitTimeSeconds(10) // Long polling;
.withMaxNumberOfMessages(1); // Max is 10
ReceiveMessageRequest receiveMessageRequest = ReceiveMessageRequest.builder()
.waitTimeSeconds(10)
.maxNumberOfMessages(10)
.build();
List<Message> sqsMessages = sqs.receiveMessage(receiveMessageRequest)
.getMessages();
List<Message> sqsMessages = sqsClient.receiveMessage(receiveMessageRequest)
.messages();
sqsMessages.get(0)
.getAttributes();
.attributes();
sqsMessages.get(0)
.getBody();
.body();
// Delete a message from a queue
DeleteMessageRequest deleteMessageRequest = DeleteMessageRequest.builder()
.queueUrl(fifoQueueUrl)
.receiptHandle(sqsMessages.get(0)
.receiptHandle())
.build();
sqs.deleteMessage(new DeleteMessageRequest().withQueueUrl(fifoQueueUrl)
.withReceiptHandle(sqsMessages.get(0)
.getReceiptHandle()));
sqsClient.deleteMessage(deleteMessageRequest);
// Monitoring
GetQueueAttributesRequest getQueueAttributesRequest = new GetQueueAttributesRequest(standardQueueUrl).withAttributeNames("All");
GetQueueAttributesResult getQueueAttributesResult = sqs.getQueueAttributes(getQueueAttributesRequest);
System.out.println(String.format("The number of messages on the queue: %s", getQueueAttributesResult.getAttributes()
GetQueueAttributesRequest getQueueAttributesRequestForMonitoring = GetQueueAttributesRequest.builder()
.queueUrl(standardQueueUrl)
.build();
GetQueueAttributesResponse attributesResponse = sqsClient.getQueueAttributes(getQueueAttributesRequestForMonitoring);
System.out.println(String.format("The number of messages on the queue: %s", attributesResponse.attributes()
.get("ApproximateNumberOfMessages")));
System.out.println(String.format("The number of messages in flight: %s", getQueueAttributesResult.getAttributes()
System.out.println(String.format("The number of messages in flight: %s", attributesResponse.attributes()
.get("ApproximateNumberOfMessagesNotVisible")));
}

View File

@ -5,6 +5,14 @@
<modelVersion>4.0.0</modelVersion>
<artifactId>aws-modules</artifactId>
<name>aws-modules</name>
<dependencies>
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>aws-java-sdk-dynamodb</artifactId>
<version>1.12.523</version>
<scope>compile</scope>
</dependency>
</dependencies>
<packaging>pom</packaging>
<parent>
@ -15,6 +23,7 @@
<modules>
<module>aws-app-sync</module>
<module>aws-dynamodb</module>
<module>aws-lambda-modules</module>
<module>aws-miscellaneous</module>
<module>aws-reactive</module>
@ -24,6 +33,7 @@
<properties>
<aws-java-sdk.version>1.12.331</aws-java-sdk.version>
<aws-java-sdk-v2.version>2.20.147</aws-java-sdk-v2.version>
<maven-shade-plugin.version>3.0.0</maven-shade-plugin.version>
</properties>

View File

@ -5,3 +5,4 @@
- [Collecting Stream Elements into a List in Java](https://www.baeldung.com/java-stream-to-list-collecting)
- [New Features in Java 16](https://www.baeldung.com/java-16-new-features)
- [Guide to Java 8 groupingBy Collector](https://www.baeldung.com/java-groupingby-collector)
- [Value-Based Classes in Java](https://www.baeldung.com/java-value-based-classes)

View File

@ -30,6 +30,11 @@ public final class Point {
return new Point(x, y, z);
}
@Override
public String toString() {
return "Point{" + "x=" + x + ", y=" + y + ", z=" + z + '}';
}
@Override
public boolean equals(Object other) {
if (other == null || getClass() != other.getClass())

View File

@ -1,14 +1,17 @@
package com.baeldung.value_based_class;
import java.util.ArrayList;
import java.util.List;
import org.junit.Assert;
import org.junit.Test;
public class ValueBasedClassUnitTest {
@Test
public void givenAutoboxedAndPrimitive_whenCompared_thenReturnEquals() {
int primitive_a = 125;
Integer obj_a = 125; // this is autoboxed
Assert.assertSame(primitive_a, obj_a);
List<Integer> list = new ArrayList<>();
list.add(1); // this is autoboxed
Assert.assertEquals(list.get(0), Integer.valueOf(1));
}
@Test

View File

@ -0,0 +1,89 @@
package com.baeldung.recordproperties;
import static org.junit.jupiter.api.Assertions.assertEquals;
import java.lang.reflect.Field;
import java.lang.reflect.RecordComponent;
import java.util.ArrayList;
import org.junit.jupiter.api.Test;
record Player(String name, int age, Long score) {
}
public class ReadRecordPropertiesByReflectionUnitTest {
private static final Player ERIC = new Player("Eric", 28, 4242L);
@Test
void whenUsingRecordComponent_thenGetExpectedResult() {
var fields = new ArrayList<Field>();
RecordComponent[] components = Player.class.getRecordComponents();
for (var comp : components) {
try {
Field field = ERIC.getClass()
.getDeclaredField(comp.getName());
field.setAccessible(true);
fields.add(field);
} catch (NoSuchFieldException e) {
// for simplicity, error handling is skipped
}
}
assertEquals(3, fields.size());
var nameField = fields.get(0);
var ageField = fields.get(1);
var scoreField = fields.get(2);
try {
assertEquals("name", nameField.getName());
assertEquals(String.class, nameField.getType());
assertEquals("Eric", nameField.get(ERIC));
assertEquals("age", ageField.getName());
assertEquals(int.class, ageField.getType());
assertEquals(28, ageField.get(ERIC));
assertEquals("score", scoreField.getName());
assertEquals(Long.class, scoreField.getType());
assertEquals(4242L, scoreField.get(ERIC));
} catch (IllegalAccessException exception) {
// for simplicity, error handling is skipped
}
}
@Test
void whenUsingClassGetDeclaredField_thenGetExpectedResult() {
// record has no public fields
assertEquals(0, Player.class.getFields().length);
var fields = new ArrayList<Field>();
for (var field : Player.class.getDeclaredFields()) {
field.setAccessible(true);
fields.add(field);
}
assertEquals(3, fields.size());
var nameField = fields.get(0);
var ageField = fields.get(1);
var scoreField = fields.get(2);
try {
assertEquals("name", nameField.getName());
assertEquals(String.class, nameField.getType());
assertEquals("Eric", nameField.get(ERIC));
assertEquals("age", ageField.getName());
assertEquals(int.class, ageField.getType());
assertEquals(28, ageField.get(ERIC));
assertEquals("score", scoreField.getName());
assertEquals(Long.class, scoreField.getType());
assertEquals(4242L, scoreField.get(ERIC));
} catch (IllegalAccessException ex) {
// for simplicity, error handling is skipped
}
}
}

View File

@ -0,0 +1,55 @@
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>core-java-18</artifactId>
<name>core-java-18</name>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung</groupId>
<artifactId>parent-modules</artifactId>
<version>1.0.0-SNAPSHOT</version>
<relativePath>../../</relativePath>
</parent>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>${maven-compiler-plugin.version}</version>
<configuration>
<release>${maven.compiler.release}</release>
<compilerArgs>--enable-preview</compilerArgs>
<source>${maven.compiler.source.version}</source>
<target>${maven.compiler.target.version}</target>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>${surefire.plugin.version}</version>
<configuration>
<forkCount>1</forkCount>
</configuration>
<dependencies>
<dependency>
<groupId>org.apache.maven.surefire</groupId>
<artifactId>surefire-api</artifactId>
<version>${surefire.plugin.version}</version>
</dependency>
</dependencies>
</plugin>
</plugins>
</build>
<properties>
<maven.compiler.source.version>18</maven.compiler.source.version>
<maven.compiler.target.version>18</maven.compiler.target.version>
<maven.compiler.release>18</maven.compiler.release>
<surefire.plugin.version>3.0.0-M5</surefire.plugin.version>
</properties>
</project>

View File

@ -0,0 +1,27 @@
package com.baeldung.finalization_closeable_cleaner;
import java.io.FileInputStream;
import java.io.IOException;
public class FinalizationExamples {
FileInputStream fis = null;
public void readFileOperationWithFinalization() throws IOException {
try {
fis = new FileInputStream("input.txt");
// perform operation on the file
System.out.println(fis.readAllBytes().length);
} finally {
if (fis != null)
fis.close();
}
}
public void readFileOperationWithTryWith() throws IOException {
try (FileInputStream fis = new FileInputStream("input.txt")) {
// perform operations
System.out.println(fis.readAllBytes().length);
}
}
}

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@ -0,0 +1,48 @@
package com.baeldung.finalization_closeable_cleaner;
import java.lang.ref.Cleaner;
public class MyCleanerResourceClass implements AutoCloseable {
private static Resource resource;
private static final Cleaner cleaner = Cleaner.create();
private final Cleaner.Cleanable cleanable;
public MyCleanerResourceClass() {
resource = new Resource();
this.cleanable = cleaner.register(this, new CleaningState());
}
public void useResource() {
// using the resource here
resource.use();
}
@Override
public void close() {
// perform actions to close all underlying resources
this.cleanable.clean();
}
static class CleaningState implements Runnable {
CleaningState() {
// constructor
}
@Override
public void run() {
// some cleanup action
System.out.println("Cleanup done");
}
}
static class Resource {
void use() {
System.out.println("Using the resource");
}
void close() {
System.out.println("Cleanup done");
}
}
}

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@ -0,0 +1,25 @@
package com.baeldung.finalization_closeable_cleaner;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
public class MyCloseableResourceClass implements AutoCloseable {
private final FileInputStream fis;
public MyCloseableResourceClass() throws FileNotFoundException {
this.fis = new FileInputStream("src/main/resources/file.txt");
}
public int getByteLength() throws IOException {
System.out.println("Some operation");
return this.fis.readAllBytes().length;
}
@Override
public void close() throws IOException {
System.out.println("Finalized object");
this.fis.close();
}
}

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@ -0,0 +1,24 @@
package com.baeldung.finalization_closeable_cleaner;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
public class MyFinalizableResourceClass {
private FileInputStream fis;
public MyFinalizableResourceClass() throws FileNotFoundException {
this.fis = new FileInputStream("src/main/resources/file.txt");
}
public int getByteLength() throws IOException {
System.out.println("Some operation");
return this.fis.readAllBytes().length;
}
@Override
protected void finalize() throws Throwable {
System.out.println("Finalized object");
this.fis.close();
}
}

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@ -0,0 +1 @@
This is a test file.

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@ -0,0 +1,36 @@
package com.baeldung.finalization_closeable_cleaner;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
import java.io.IOException;
import org.junit.Assert;
import org.junit.Test;
public class FinalizationCloseableCleanerUnitTest {
@Test
public void givenMyFinalizationResource_whenUsingFinalize_thenShouldClean() {
assertDoesNotThrow(() -> {
MyFinalizableResourceClass mfr = new MyFinalizableResourceClass();
mfr.getByteLength();
});
}
@Test
public void givenMyCleanerResource_whenUsingCleanerAPI_thenShouldClean() {
assertDoesNotThrow(() -> {
try (MyCleanerResourceClass myCleanerResourceClass = new MyCleanerResourceClass()) {
myCleanerResourceClass.useResource();
}
});
}
@Test
public void givenCloseableResource_whenUsingTryWith_thenShouldClose() throws IOException {
int length = 0;
try (MyCloseableResourceClass mcr = new MyCloseableResourceClass()) {
length = mcr.getByteLength();
}
Assert.assertEquals(20, length);
}
}

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@ -1,2 +1,5 @@
## Relevant Articles
- [Sequenced Collections in Java 21](https://www.baeldung.com/java-21-sequenced-collections)
- [String Templates in Java 21](https://www.baeldung.com/java-21-string-templates)
- [Unnamed Classes and Instance Main Methods in Java 21](https://www.baeldung.com/java-21-unnamed-class-instance-main)
- [Unnamed Patterns and Variables in Java 21](https://www.baeldung.com/java-unnamed-patterns-variables)

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@ -12,6 +12,12 @@
<version>0.0.1-SNAPSHOT</version>
</parent>
<properties>
<maven.compiler.source.version>21</maven.compiler.source.version>
<maven.compiler.target.version>21</maven.compiler.target.version>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<build>
<plugins>
<plugin>
@ -20,14 +26,22 @@
<configuration>
<source>21</source>
<target>21</target>
<compilerArgs>--enable-preview</compilerArgs>
<!-- Needed due to a bug with JDK 21, described here: https://issues.apache.org/jira/browse/MCOMPILER-546?page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel&focusedCommentId=17767513 -->
<debug>false</debug>
<compilerArgs>
<arg>--enable-preview</arg>
</compilerArgs>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<configuration>
<argLine>--enable-preview</argLine>
</configuration>
</plugin>
</plugins>
</build>
<properties>
<maven.compiler.source.version>21</maven.compiler.source.version>
<maven.compiler.target.version>21</maven.compiler.target.version>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
</project>

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@ -0,0 +1,11 @@
package com.baeldung.unnamed.variables;
public record Car<T extends Engine>(String name, String color, T engine) { }
abstract class Engine { }
class GasEngine extends Engine { }
class ElectricEngine extends Engine { }
class HybridEngine extends Engine { }

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@ -0,0 +1,50 @@
package com.baeldung.unnamed.variables;
public class UnnamedPatterns {
static String getObjectsColorWithNamedPattern(Object object) {
if (object instanceof Car(String name, String color, Engine engine)) {
return color;
}
return "No color!";
}
static String getObjectsColorWithUnnamedPattern(Object object) {
if (object instanceof Car(_, String color, _)) {
return color;
}
return "No color!";
}
static String getObjectsColorWithSwitchAndNamedPattern(Object object) {
return switch (object) {
case Car(String name, String color, Engine engine) -> color;
default -> "No color!";
};
}
static String getObjectsColorWithSwitchAndUnnamedPattern(Object object) {
return switch (object) {
case Car(_, String color, _) -> color;
default -> "No color!";
};
}
static String getEngineTypeWithNamedPattern(Car<?> car) {
return switch (car) {
case Car(String name, String color, GasEngine engine) -> "gas";
case Car(String name, String color, ElectricEngine engine) -> "electric";
case Car(String name, String color, HybridEngine engine) -> "hybrid";
default -> "none";
};
}
static String getEngineTypeWithUnnamedPattern(Car<?> car) {
return switch (car) {
case Car(_, _, GasEngine _) -> "gas";
case Car(_, _, ElectricEngine _) -> "electric";
case Car(_, _, HybridEngine _) -> "hybrid";
default -> "none";
};
}
}

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@ -0,0 +1,134 @@
package com.baeldung.unnamed.variables;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Queue;
class Transaction implements AutoCloseable {
@Override
public void close() {
System.out.println("Closed!");
}
}
public class UnnamedVariables {
static int countCarsOverLimitWithNamedVariable(Collection<Car<?>> cars, int limit) {
var total = 0;
var totalOverLimit = 0;
for (var car : cars) {
total++;
if (total > limit) {
totalOverLimit++;
// side effect
}
}
return totalOverLimit;
}
static int countCarsOverLimitWithUnnamedVariable(Collection<Car<?>> cars, int limit) {
var total = 0;
var totalOverLimit = 0;
for (var _ : cars) {
total++;
if (total > limit) {
totalOverLimit++;
// side effect
}
}
return totalOverLimit;
}
static void sendNotificationToCarsWithNamedVariable(Collection<Car<?>> cars) {
sendOneTimeNotification();
for (int i = 0; i < cars.size(); i++) {
// Notify car
}
}
static void sendNotificationToCarsWithUnnamedVariable(Collection<Car<?>> cars) {
for (int i = 0, _ = sendOneTimeNotification(); i < cars.size(); i++) {
// Notify car
}
}
private static int sendOneTimeNotification() {
System.out.println("Sending one time notification!");
return 1;
}
static Car<?> removeThreeCarsAndReturnFirstRemovedWithNamedVariables(Queue<Car<?>> cars) {
var x = cars.poll();
var y = cars.poll();
var z = cars.poll();
return x;
}
static Car<?> removeThreeCarsAndReturnFirstRemovedWithUnnamedVariables(Queue<Car<?>> cars) {
var car = cars.poll();
var _ = cars.poll();
var _ = cars.poll();
return car;
}
static void handleCarExceptionWithNamedVariables(Car<?> car) {
try {
someOperationThatFails(car);
} catch (IllegalStateException ex) {
System.out.println("Got an illegal state exception for: " + car.name());
} catch (RuntimeException ex) {
System.out.println("Got a runtime exception!");
}
}
static void handleCarExceptionWithUnnamedVariables(Car<?> car) {
try {
someOperationThatFails(car);
} catch (IllegalStateException | NumberFormatException _) {
System.out.println("Got an illegal state exception for: " + car.name());
} catch (RuntimeException _) {
System.out.println("Got a runtime exception!");
}
}
static void obtainTransactionAndUpdateCarWithNamedVariables(Car<?> car) {
try (var transaction = new Transaction()) {
updateCar(car);
}
}
static void obtainTransactionAndUpdateCarWithUnnamedVariables(Car<?> car) {
try (var _ = new Transaction()) {
updateCar(car);
}
}
static void updateCar(Car<?> car) {
// Some update logic
System.out.println("Car updated!");
}
static Map<String, List<Car<?>>> getCarsByFirstLetterWithNamedVariables(List<Car<?>> cars) {
Map<String, List<Car<?>>> carMap = new HashMap<>();
cars.forEach(car ->
carMap.computeIfAbsent(car.name().substring(0, 1), firstLetter -> new ArrayList<>()).add(car)
);
return carMap;
}
static Map<String, List<Car<?>>> getCarsByFirstLetterWithUnnamedVariables(List<Car<?>> cars) {
Map<String, List<Car<?>>> carMap = new HashMap<>();
cars.forEach(car ->
carMap.computeIfAbsent(car.name().substring(0, 1), _ -> new ArrayList<>()).add(car)
);
return carMap;
}
private static void someOperationThatFails(Car<?> car) {
throw new IllegalStateException("Triggered exception for: " + car.name());
}
}

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@ -0,0 +1,3 @@
void main() {
System.out.println("Hello, World!");
}

View File

@ -0,0 +1,7 @@
package com.baeldung.unnamedclasses;
public class HelloWorldChild extends HelloWorldSuper {
void main() {
System.out.println("Hello, World!");
}
}

View File

@ -0,0 +1,7 @@
package com.baeldung.unnamedclasses;
public class HelloWorldSuper {
public static void main(String[] args) {
System.out.println("Hello from the superclass");
}
}

View File

@ -0,0 +1,6 @@
private String getMessage() {
return "Hello, World!";
}
void main() {
System.out.println(getMessage());
}

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@ -0,0 +1,13 @@
package com.baeldung.unnamed.variables;
import java.util.List;
class CarScenario {
protected final List<Car<?>> cars = List.of(
new Car<>("Mitsubishi", "blue", new GasEngine()),
new Car<>("Toyota", "red", new ElectricEngine()),
new Car<>("Jaguar", "white", new HybridEngine())
);
}

View File

@ -0,0 +1,44 @@
package com.baeldung.unnamed.variables;
import static com.baeldung.unnamed.variables.UnnamedPatterns.getEngineTypeWithNamedPattern;
import static com.baeldung.unnamed.variables.UnnamedPatterns.getEngineTypeWithUnnamedPattern;
import static com.baeldung.unnamed.variables.UnnamedPatterns.getObjectsColorWithNamedPattern;
import static com.baeldung.unnamed.variables.UnnamedPatterns.getObjectsColorWithSwitchAndNamedPattern;
import static com.baeldung.unnamed.variables.UnnamedPatterns.getObjectsColorWithSwitchAndUnnamedPattern;
import static com.baeldung.unnamed.variables.UnnamedPatterns.getObjectsColorWithUnnamedPattern;
import static org.junit.jupiter.api.Assertions.assertEquals;
import org.junit.jupiter.api.Test;
public class UnnamedPatternsUnitTest extends CarScenario {
@Test
public void whenExtractingColorWithNamedPatterns_thenReturnBlue() {
assertEquals("blue", getObjectsColorWithNamedPattern(cars.get(0)));
}
@Test
public void whenExtractingColorWithUnnamedPatterns_thenReturnBlue() {
assertEquals("blue", getObjectsColorWithUnnamedPattern(cars.get(0)));
}
@Test
public void whenExtractingColorWithSwitchAndNamedPatterns_thenReturnBlue() {
assertEquals("blue", getObjectsColorWithSwitchAndNamedPattern(cars.get(0)));
}
@Test
public void whenExtractingColorWithSwitchAndUnnamedPatterns_thenReturnBlue() {
assertEquals("blue", getObjectsColorWithSwitchAndUnnamedPattern(cars.get(0)));
}
@Test
public void whenExtractingEngineTypeWithNamedPatterns_thenReturnGas() {
assertEquals("gas", getEngineTypeWithNamedPattern(cars.get(0)));
}
@Test
public void whenExtractingEngineTypeWithUnnamedPatterns_thenReturnGas() {
assertEquals("gas", getEngineTypeWithUnnamedPattern(cars.get(0)));
}
}

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@ -0,0 +1,93 @@
package com.baeldung.unnamed.variables;
import static com.baeldung.unnamed.variables.UnnamedVariables.countCarsOverLimitWithNamedVariable;
import static com.baeldung.unnamed.variables.UnnamedVariables.countCarsOverLimitWithUnnamedVariable;
import static com.baeldung.unnamed.variables.UnnamedVariables.getCarsByFirstLetterWithNamedVariables;
import static com.baeldung.unnamed.variables.UnnamedVariables.getCarsByFirstLetterWithUnnamedVariables;
import static com.baeldung.unnamed.variables.UnnamedVariables.handleCarExceptionWithNamedVariables;
import static com.baeldung.unnamed.variables.UnnamedVariables.handleCarExceptionWithUnnamedVariables;
import static com.baeldung.unnamed.variables.UnnamedVariables.obtainTransactionAndUpdateCarWithNamedVariables;
import static com.baeldung.unnamed.variables.UnnamedVariables.obtainTransactionAndUpdateCarWithUnnamedVariables;
import static com.baeldung.unnamed.variables.UnnamedVariables.removeThreeCarsAndReturnFirstRemovedWithNamedVariables;
import static com.baeldung.unnamed.variables.UnnamedVariables.removeThreeCarsAndReturnFirstRemovedWithUnnamedVariables;
import static com.baeldung.unnamed.variables.UnnamedVariables.sendNotificationToCarsWithNamedVariable;
import static com.baeldung.unnamed.variables.UnnamedVariables.sendNotificationToCarsWithUnnamedVariable;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
import static org.junit.jupiter.api.Assertions.assertEquals;
import java.util.LinkedList;
import org.junit.jupiter.api.Test;
public class UnnamedVariablesUnitTest extends CarScenario {
@Test
public void whenCountingCarsOverLimitWithNamedVariables_thenShouldReturnOne() {
assertEquals(1, countCarsOverLimitWithNamedVariable(cars, 2));
}
@Test
public void whenCountingCarsOverLimitWithUnnamedVariables_thenShouldReturnOne() {
assertEquals(1, countCarsOverLimitWithUnnamedVariable(cars, 2));
}
@Test
public void whenNotifyingCarsWithNamedVariables_thenShouldNotFail() {
assertDoesNotThrow(() -> sendNotificationToCarsWithNamedVariable(cars));
}
@Test
public void whenNotifyingCarsWithUnnamedVariables_thenShouldNotFail() {
assertDoesNotThrow(() -> sendNotificationToCarsWithUnnamedVariable(cars));
}
@Test
public void whenPollingCarsWithNamedVariables_thenReturnFirstOneAndEmptyQueue() {
var carQueue = new LinkedList<>(cars);
assertEquals("Mitsubishi", removeThreeCarsAndReturnFirstRemovedWithNamedVariables(carQueue).name());
assertEquals(0, carQueue.size());
}
@Test
public void whenPollingCarsWithUnnamedVariables_thenReturnFirstOneAndEmptyQueue() {
var carQueue = new LinkedList<>(cars);
assertEquals("Mitsubishi", removeThreeCarsAndReturnFirstRemovedWithUnnamedVariables(carQueue).name());
assertEquals(0, carQueue.size());
}
@Test
public void whenHandlingExceptionWithNamedVariables_thenNoExceptionIsThrown() {
assertDoesNotThrow(() -> handleCarExceptionWithNamedVariables(cars.get(0)));
}
@Test
public void whenHandlingExceptionWithUnnamedVariables_thenNoExceptionIsThrown() {
assertDoesNotThrow(() -> handleCarExceptionWithUnnamedVariables(cars.get(0)));
}
@Test
public void whenHandlingTransactionUpdateWithNamedVariables_thenNoExceptionIsThrown() {
assertDoesNotThrow(() -> obtainTransactionAndUpdateCarWithNamedVariables(cars.get(0)));
}
@Test
public void whenHandlingTransactionUpdateWithUnnamedVariables_thenNoExceptionIsThrown() {
assertDoesNotThrow(() -> obtainTransactionAndUpdateCarWithUnnamedVariables(cars.get(0)));
}
@Test
public void whenGettingCarsByFirstLetterWithNamedVariables_thenHaveThreeKeys() {
var carsByLetter = getCarsByFirstLetterWithNamedVariables(cars);
assertEquals(1, carsByLetter.get("M").size());
assertEquals(1, carsByLetter.get("T").size());
assertEquals(1, carsByLetter.get("J").size());
}
@Test
public void whenGettingCarsByFirstLetterWithUnnamedVariables_thenHaveThreeKeys() {
var carsByLetter = getCarsByFirstLetterWithUnnamedVariables(cars);
assertEquals(1, carsByLetter.get("M").size());
assertEquals(1, carsByLetter.get("T").size());
assertEquals(1, carsByLetter.get("J").size());
}
}

View File

@ -4,3 +4,4 @@ This module contains articles about Java 9 streams
### Relevant Articles:
- [How to Break from Java Stream forEach](https://www.baeldung.com/java-break-stream-foreach)
- [Creating Stream of Regex Matches](https://www.baeldung.com/java-stream-regex-matches)

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@ -10,3 +10,4 @@ This module contains articles about arrays conversion in Java
- [Convert Java Array to Iterable](https://www.baeldung.com/java-array-convert-to-iterable)
- [Converting an int[] to HashSet in Java](https://www.baeldung.com/java-converting-int-array-to-hashset)
- [Convert an ArrayList of String to a String Array in Java](https://www.baeldung.com/java-convert-string-arraylist-array)
- [Convert Char Array to Int Array in Java](https://www.baeldung.com/java-convert-char-int-array)

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@ -0,0 +1,67 @@
package com.baeldung.array.conversions;
import java.util.Arrays;
public class CharArrayToIntArrayUtils {
static int[] usingGetNumericValueMethod(char[] chars) {
if (chars == null) {
return null;
}
int[] ints = new int[chars.length];
for (int i = 0; i < chars.length; i++) {
ints[i] = Character.getNumericValue(chars[i]);
}
return ints;
}
static int[] usingDigitMethod(char[] chars) {
if (chars == null) {
return null;
}
int[] ints = new int[chars.length];
for (int i = 0; i < chars.length; i++) {
ints[i] = Character.digit(chars[i], 10);
}
return ints;
}
static int[] usingStreamApiMethod(char[] chars) {
if (chars == null) {
return null;
}
return new String(chars).chars()
.map(c -> c - 48)
.toArray();
}
static int[] usingParseIntMethod(char[] chars) {
if (chars == null) {
return null;
}
int[] ints = new int[chars.length];
for (int i = 0; i < chars.length; i++) {
ints[i] = Integer.parseInt(String.valueOf(chars[i]));
}
return ints;
}
static int[] usingArraysSetAllMethod(char[] chars) {
if (chars == null) {
return null;
}
int[] ints = new int[chars.length];
Arrays.setAll(ints, i -> Character.getNumericValue(chars[i]));
return ints;
}
}

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@ -0,0 +1,54 @@
package com.baeldung.array.conversions;
import static org.junit.jupiter.api.Assertions.assertArrayEquals;
import org.junit.jupiter.api.Test;
class CharArrayToIntArrayUtilsUnitTest {
@Test
void givenCharArray_whenUsingGetNumericValueMethod_shouldGetIntArray() {
int[] expected = { 2, 3, 4, 5 };
char[] chars = { '2', '3', '4', '5' };
int[] result = CharArrayToIntArrayUtils.usingGetNumericValueMethod(chars);
assertArrayEquals(expected, result);
}
@Test
void givenCharArray_whenUsingDigitMethod_shouldGetIntArray() {
int[] expected = { 1, 2, 3, 6 };
char[] chars = { '1', '2', '3', '6' };
int[] result = CharArrayToIntArrayUtils.usingDigitMethod(chars);
assertArrayEquals(expected, result);
}
@Test
void givenCharArray_whenUsingStreamApi_shouldGetIntArray() {
int[] expected = { 9, 8, 7, 6 };
char[] chars = { '9', '8', '7', '6' };
int[] result = CharArrayToIntArrayUtils.usingStreamApiMethod(chars);
assertArrayEquals(expected, result);
}
@Test
void givenCharArray_whenUsingParseIntMethod_shouldGetIntArray() {
int[] expected = { 9, 8, 7, 6 };
char[] chars = { '9', '8', '7', '6' };
int[] result = CharArrayToIntArrayUtils.usingParseIntMethod(chars);
assertArrayEquals(expected, result);
}
@Test
void givenCharArray_whenUsingArraysSetAllMethod_shouldGetIntArray() {
int[] expected = { 4, 9, 2, 3 };
char[] chars = { '4', '9', '2', '3' };
int[] result = CharArrayToIntArrayUtils.usingArraysSetAllMethod(chars);
assertArrayEquals(expected, result);
}
}

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@ -9,3 +9,4 @@ This module contains complete guides about arrays in Java
- [Guide to ArrayStoreException](https://www.baeldung.com/java-arraystoreexception)
- [Creating a Generic Array in Java](https://www.baeldung.com/java-generic-array)
- [Maximum Size of Java Arrays](https://www.baeldung.com/java-arrays-max-size)
- [Merge Two Arrays and Remove Duplicates in Java](https://www.baeldung.com/java-merge-two-arrays-delete-duplicates)

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@ -0,0 +1,2 @@
## Relevant Articles
- [Find the Middle Element of an Array in Java](https://www.baeldung.com/java-array-middle-item)

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@ -14,4 +14,3 @@ This module contains articles about advanced operations on arrays in Java. They
- [Slicing Arrays in Java](https://www.baeldung.com/java-slicing-arrays)
- [Combining Two or More Byte Arrays](https://www.baeldung.com/java-concatenate-byte-arrays)
- [Calculating the Sum of Two Arrays in Java](https://www.baeldung.com/java-sum-arrays-element-wise)
- [Find the Middle Element of an Array in Java](https://www.baeldung.com/java-array-middle-item)

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@ -5,3 +5,4 @@ This module contains articles about Java Character Class
### Relevant Articles:
- [Character#isAlphabetic vs. Character#isLetter](https://www.baeldung.com/java-character-isletter-isalphabetic)
- [Difference Between Javas “char” and “String”](https://www.baeldung.com/java-char-vs-string)
- [Increment Character in Java](https://www.baeldung.com/java-char-sequence)

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@ -0,0 +1,29 @@
package com.baeldung.incrementchar;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
class IncrementCharUnitTest {
@Test
void whenUsingForLoop_thenGenerateCharacters(){
final List<Character> allCapitalCharacters = Arrays.asList('A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z');
List<Character> characters = new ArrayList<>();
for (char character = 'A'; character <= 'Z'; character++) {
characters.add(character);
}
Assertions.assertEquals(characters, allCapitalCharacters);
}
@Test
void whenUsingStreams_thenGenerateCharacters() {
final List<Character> allCapitalCharacters = Arrays.asList('A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z');
final List<Character> characters = IntStream.rangeClosed('A', 'Z').mapToObj(c -> (char) c).collect(Collectors.toList());
Assertions.assertEquals(characters, allCapitalCharacters);
}
}

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@ -5,4 +5,6 @@
### Relevant Articles:
- [Introduction to Roaring Bitmap](https://www.baeldung.com/java-roaring-bitmap-intro)
- [Creating Custom Iterator in Java](https://www.baeldung.com/java-creating-custom-iterator)
- [Difference Between Arrays.sort() and Collections.sort()](https://www.baeldung.com/java-arrays-collections-sort-methods)
- [Skipping the First Iteration in Java](https://www.baeldung.com/java-skip-first-iteration)
- More articles: [[<-- prev]](/core-java-modules/core-java-collections-4)

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@ -0,0 +1,126 @@
package com.baeldung.skippingfirstelement;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
public class SkipFirstElementExample {
private final List<String> stringList = new ArrayList<>();
private final Set<String> stringSet = new HashSet<>();
private final Map<String, String> stringMap = new HashMap<>();
public SkipFirstElementExample() {
// Initializing a List
stringList.add("Monday");
stringList.add("Tuesday");
stringList.add("Wednesday");
stringList.add("Thursday");
stringList.add("Friday");
stringList.add("Saturday");
stringList.add("Sunday");
// Initializing a Set
stringSet.add("Monday");
stringSet.add("Tuesday");
stringSet.add("Wednesday");
stringSet.add("Thursday");
stringSet.add("Friday");
stringSet.add("Saturday");
stringSet.add("Sunday");
// Initializing a Map
stringMap.put("Monday", "The day when coffee is a life support system.");
stringMap.put("Tuesday", "The day you realize that Monday's optimism was a lie.");
stringMap.put("Wednesday", "Hump Day, or as it's known, the 'Is it Friday yet?' day.");
stringMap.put("Thursday", "The day that says, 'Hold my beer, Friday is coming!'");
stringMap.put("Friday", "The golden child of the weekdays. The superhero of the workweek.");
stringMap.put("Saturday", "The day of rest? More like the day of 'What can I binge-watch next?'");
stringMap.put("Sunday", "The day before you have to adult again.");
}
void skippingFirstElementInListWithForLoop(List<String> stringList) {
for (int i = 1; i < stringList.size(); i++) {
process(stringList.get(i));
}
}
void skippingFirstElementInListWithWhileLoop(List<String> stringList) {
final Iterator<String> iterator = stringList.iterator();
if (iterator.hasNext()) {
iterator.next();
}
while (iterator.hasNext()) {
process(iterator.next());
}
}
void skippingFirstElementInSetWithWhileLoop(Set<String> stringSet) {
final Iterator<String> iterator = stringSet.iterator();
if (iterator.hasNext()) {
iterator.next();
}
while (iterator.hasNext()) {
process(iterator.next());
}
}
void skippingFirstElementInListWithWhileLoopStoringFirstElement(List<String> stringList) {
final Iterator<String> iterator = stringList.iterator();
String firstElement = null;
if (iterator.hasNext()) {
firstElement = iterator.next();
}
while (iterator.hasNext()) {
process(iterator.next());
// additional logic using fistElement
}
}
void skippingFirstElementInMapWithStreamSkip(Map<String, String> stringMap) {
stringMap.entrySet().stream().skip(1).forEach(this::process);
}
void skippingFirstElementInListWithSubList(List<String> stringList) {
for (final String element : stringList.subList(1, stringList.size())) {
process(element);
}
}
void skippingFirstElementInListWithForLoopWithAdditionalCheck(List<String> stringList) {
for (int i = 0; i < stringList.size(); i++) {
if (i == 0) {
// do something else
} else {
process(stringList.get(i));
}
}
}
void skippingFirstElementInListWithWhileLoopWithCounter(List<String> stringList) {
int counter = 0;
while (counter < stringList.size()) {
if (counter != 0) {
process(stringList.get(counter));
}
++counter;
}
}
void skippingFirstElementInListWithReduce(List<String> stringList) {
stringList.stream().reduce((skip, element) -> {
process(element);
return element;
});
}
protected void process(String string) {
System.out.println(string);
}
protected void process(Entry<String, String> mapEntry) {
System.out.println(mapEntry);
}
}

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package com.baeldung.skippingfirstelement;
import static org.junit.jupiter.api.Assertions.*;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.stream.Stream;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.condition.EnabledForJreRange;
import org.junit.jupiter.api.condition.JRE;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.Arguments;
import org.junit.jupiter.params.provider.MethodSource;
@EnabledForJreRange(min = JRE.JAVA_9)
class SkipFirstElementExampleUnitTest {
private static TestableSkipFirstElement testableSkip = new TestableSkipFirstElement();
@BeforeEach
void setup() {
testableSkip.reset();
}
private static Stream<Arguments> listProvider() {
return Stream.of(
Arguments.of(
List.of("Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"),
List.of("Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"))
);
}
private static Stream<Arguments> mapProvider() {
return Stream.of(
Arguments.of(
Map.of(
"Monday", "The day when coffee is a life support system.",
"Tuesday", "The day you realize that Monday's optimism was a lie.",
"Wednesday", "Hump Day, or as it's known, the 'Is it Friday yet?' day.",
"Thursday", "The day that says, 'Hold my beer, Friday is coming!'",
"Friday", "The golden child of the weekdays. The superhero of the workweek.",
"Saturday", "The day of rest? More like the day of 'What can I binge-watch next?'",
"Sunday", "The day before you have to adult again."
)
)
);
}
@ParameterizedTest
@MethodSource("listProvider")
void skippingFirstElementInListWithForLoop(List<String> input, List<String> expected) {
testableSkip.skippingFirstElementInListWithForLoop(input);
List<?> actual = testableSkip.getResult();
assertEquals(actual, expected);
}
@ParameterizedTest
@MethodSource("listProvider")
void skippingFirstElementInListWithWhileLoop(List<String> input, List<String> expected) {
testableSkip.skippingFirstElementInListWithWhileLoop(input);
List<?> actual = testableSkip.getResult();
assertEquals(actual, expected);
}
@ParameterizedTest
@MethodSource("listProvider")
void skippingFirstElementInSetWithWhileLoop(List<String> input) {
testableSkip.skippingFirstElementInSetWithWhileLoop(new HashSet<>(input));
Set<?> actual = new HashSet<>(testableSkip.getResult());
assertEquals(actual.size(), input.size() - 1);
}
@ParameterizedTest
@MethodSource("listProvider")
void skippingFirstElementInListWithWhileLoopStoringFirstElement(List<String> input, List<String> expected) {
testableSkip.skippingFirstElementInListWithWhileLoopStoringFirstElement(input);
List<?> actual = testableSkip.getResult();
assertEquals(actual, expected);
}
@ParameterizedTest
@MethodSource("mapProvider")
void skippingFirstElementInMapWithStreamSkip(Map<String, String> input) {
testableSkip.skippingFirstElementInMapWithStreamSkip(input);
List<?> actual = testableSkip.getResult();
assertEquals(actual.size(), input.size() - 1);
}
@ParameterizedTest
@MethodSource("listProvider")
void skippingFirstElementInListWithSubList(List<String> input, List<String> expected) {
testableSkip.skippingFirstElementInListWithSubList(input);
List<?> actual = testableSkip.getResult();
assertEquals(actual, expected);
}
@ParameterizedTest
@MethodSource("listProvider")
void skippingFirstElementInListWithForLoopWithAdditionalCheck(List<String> input, List<String> expected) {
testableSkip.skippingFirstElementInListWithForLoopWithAdditionalCheck(input);
List<?> actual = testableSkip.getResult();
assertEquals(actual, expected);
}
@ParameterizedTest
@MethodSource("listProvider")
void skippingFirstElementInListWithWhileLoopWithCounter(List<String> input, List<String> expected) {
testableSkip.skippingFirstElementInListWithWhileLoopWithCounter(input);
List<?> actual = testableSkip.getResult();
assertEquals(actual, expected);
}
@ParameterizedTest
@MethodSource("listProvider")
void skippingFirstElementInListWithReduce(List<String> input, List<String> expected) {
testableSkip.skippingFirstElementInListWithReduce(input);
List<?> actual = testableSkip.getResult();
assertEquals(actual, expected);
}
}

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package com.baeldung.skippingfirstelement;
import java.util.List;
public interface TestableSkip {
void reset();
List<?> getResult();
}

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package com.baeldung.skippingfirstelement;
import java.util.ArrayList;
import java.util.List;
import java.util.Map.Entry;
public class TestableSkipFirstElement extends SkipFirstElementExample implements TestableSkip {
private List<String> processedList = new ArrayList<>();
private List<Entry<String, String>> processedEntryList = new ArrayList<>();
@Override
public void process(String string) {
processedList.add(string);
}
@Override
public void process(Entry<String, String> stringEntry) {
processedEntryList.add(stringEntry);
}
@Override
public void reset() {
processedList.clear();
processedEntryList.clear();
}
@Override
public List<?> getResult() {
if (!processedList.isEmpty())
return processedList;
return processedEntryList;
}
}

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## Core Java Collections ArrayList
This module contains articles about the Java ArrayList collection
### Relevant Articles:
- [Create an ArrayList with Multiple Object Types](https://www.baeldung.com/java-arraylist-multiple-object-types)

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<project
xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>core-java-collections-array-list-2</artifactId>
<name>core-java-collections-array-list-2</name>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung.core-java-modules</groupId>
<artifactId>core-java-modules</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>${maven-compiler-plugin.source}</source>
<target>${maven-compiler-plugin.target}</target>
</configuration>
</plugin>
</plugins>
</build>
<properties>
<maven-compiler-plugin.source>17</maven-compiler-plugin.source>
<maven-compiler-plugin.target>17</maven-compiler-plugin.target>
</properties>
</project>

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package com.baeldung.list.multipleobjecttypes;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
import java.util.function.Predicate;
public class AlternativeMultipeTypeList {
public static void main(String[] args) {
// List of Parent Class
ArrayList<Number> myList = new ArrayList<>();
myList.add(1.2);
myList.add(2);
myList.add(-3.5);
// List of Interface type
ArrayList<Map> diffMapList = new ArrayList<>();
diffMapList.add(new HashMap<>());
diffMapList.add(new TreeMap<>());
diffMapList.add(new LinkedHashMap<>());
// List of Custom Object
ArrayList<CustomObject> objList = new ArrayList<>();
objList.add(new CustomObject("String"));
objList.add(new CustomObject(2));
// List via Functional Interface
List<Object> dataList = new ArrayList<>();
Predicate<Object> myPredicate = inputData -> (inputData instanceof String || inputData instanceof Integer);
UserFunctionalInterface myInterface = (listObj, data) -> {
if (myPredicate.test(data))
listObj.add(data);
else
System.out.println("Skipping input as data not allowed for class: " + data.getClass()
.getSimpleName());
return listObj;
};
myInterface.addToList(dataList, Integer.valueOf(2));
myInterface.addToList(dataList, Double.valueOf(3.33));
myInterface.addToList(dataList, "String Value");
myInterface.printList(dataList);
}
}

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package com.baeldung.list.multipleobjecttypes;
public class CustomObject {
String classData;
Integer intData;
CustomObject(String classData) {
this.classData = classData;
}
CustomObject(Integer intData) {
this.intData = intData;
}
public String getClassData() {
return this.classData;
}
public Integer getIntData() {
return this.intData;
}
}

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package com.baeldung.list.multipleobjecttypes;
import java.math.BigInteger;
import java.time.LocalDate;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class MultipleObjectTypeArrayList {
public static void main(String[] args) {
ArrayList<Object> multiTypeList = new ArrayList<>();
multiTypeList.add(Integer.valueOf(10));
multiTypeList.add(Double.valueOf(11.5));
multiTypeList.add("String Data");
multiTypeList.add(Arrays.asList(1, 2, 3));
multiTypeList.add(new CustomObject("Class Data"));
multiTypeList.add(BigInteger.valueOf(123456789));
multiTypeList.add(LocalDate.of(2023, 9, 19));
for (Object dataObj : multiTypeList) {
if (dataObj instanceof Integer intData)
System.out.println("Integer Data : " + intData);
else if (dataObj instanceof Double doubleData)
System.out.println("Double Data : " + doubleData);
else if (dataObj instanceof String stringData)
System.out.println("String Data : " + stringData);
else if (dataObj instanceof List<?> intList)
System.out.println("List Data : " + intList);
else if (dataObj instanceof CustomObject customObj)
System.out.println("CustomObject Data : " + customObj.getClassData());
else if (dataObj instanceof BigInteger bigIntData)
System.out.println("BigInteger Data : " + bigIntData);
else if (dataObj instanceof LocalDate localDate)
System.out.println("LocalDate Data : " + localDate.toString());
}
}
}

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package com.baeldung.list.multipleobjecttypes;
import java.util.List;
@FunctionalInterface
public interface UserFunctionalInterface {
List<Object> addToList(List<Object> list, Object data);
default void printList(List<Object> dataList) {
for (Object data : dataList) {
if (data instanceof String stringData)
System.out.println("String Data: " + stringData);
if (data instanceof Integer intData)
System.out.println("Integer Data: " + intData);
}
}
}

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@ -3,3 +3,4 @@
This module contains articles about conversions among Collection types in Java.
### Relevant Articles:
- [Converting HashMap Values to an ArrayList in Java](https://www.baeldung.com/java-hashmap-arraylist)

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@ -0,0 +1,2 @@
## Relevant Articles
- [Check if a List Contains a String Element While Ignoring Case](https://www.baeldung.com/java-list-search-case-insensitive)

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@ -0,0 +1,15 @@
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>core-java-collections-list-6</artifactId>
<name>core-java-collections-list-6</name>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung.core-java-modules</groupId>
<artifactId>core-java-modules</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
</project>

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package com.baeldung.lists;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertTrue;
import java.util.List;
import org.junit.jupiter.api.Test;
public class StringListCaseInsensitiveContainsUnitTest {
private final static List<String> THE_LIST = List.of("Game of Thrones", "Forrest Gump", "American Beauty", "Pretty Woman", "Catch Me If You Can");
@Test
void whenUsingContains_thenGetExpectedResult() {
assertFalse(THE_LIST.contains("catch me if you can"));
}
boolean ignoreCaseContainsForLoop(List<String> list, String value) {
for (String e : list) {
if (value.equalsIgnoreCase(e))
return true;
}
return false;
}
@Test
void whenUsingIgnoreCaseContainsForLoop_thenGetExpectedResult() {
assertTrue(ignoreCaseContainsForLoop(THE_LIST, "CATCH me if you CAN"));
assertTrue(ignoreCaseContainsForLoop(THE_LIST, "game of thrones"));
assertFalse(ignoreCaseContainsForLoop(THE_LIST, "The Godfather"));
}
@Test
void whenUsingIgnoreCaseContainsStream_thenGetExpectedResult() {
assertTrue(THE_LIST.stream()
.anyMatch(e -> e.equalsIgnoreCase("CATCH me if you CAN")));
assertTrue(THE_LIST.stream()
.anyMatch("game of thrones"::equalsIgnoreCase));
assertFalse(THE_LIST.stream()
.anyMatch("The Godfather"::equalsIgnoreCase));
}
}

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@ -1,76 +0,0 @@
package java.com.baeldung.objecttomap;
import com.google.gson.Gson;
import org.junit.Assert;
import org.junit.Test;
import wiremock.com.fasterxml.jackson.core.type.TypeReference;
import wiremock.com.fasterxml.jackson.databind.ObjectMapper;
import wiremock.com.google.common.reflect.TypeToken;
import java.lang.reflect.Field;
import java.util.HashMap;
import java.util.Map;
public class ObjectToMapUnitTest {
Employee employee = new Employee("John", 3000.0);
@Test
public void givenJavaObject_whenUsingReflection_thenConvertToMap() throws IllegalAccessException {
Map<String, Object> map = convertUsingReflection(employee);
Assert.assertEquals(employee.getName(), map.get("name"));
Assert.assertEquals(employee.getSalary(), map.get("salary"));
}
private Map<String, Object> convertUsingReflection(Object object) throws IllegalAccessException {
Map<String, Object> map = new HashMap<>();
Field[] fields = object.getClass().getDeclaredFields();
for (Field field : fields) {
field.setAccessible(true);
map.put(field.getName(), field.get(object));
}
return map;
}
@Test
public void givenJavaObject_whenUsingJackson_thenConvertToMap() {
ObjectMapper objectMapper = new ObjectMapper();
Map<String, Object> map = objectMapper.convertValue(employee, new TypeReference<Map<String, Object>>() {});
Assert.assertEquals(employee.getName(), map.get("name"));
Assert.assertEquals(employee.getSalary(), map.get("salary"));
}
@Test
public void givenJavaObject_whenUsingGson_thenConvertToMap() {
Gson gson = new Gson();
String json = gson.toJson(employee);
Map<String, Object> map = gson.fromJson(json, new TypeToken<Map<String, Object>>() {}.getType());
Assert.assertEquals(employee.getName(), map.get("name"));
Assert.assertEquals(employee.getSalary(), map.get("salary"));
}
private static class Employee {
private String name;
private Double salary;
public Employee(String name, Double salary) {
this.name = name;
this.salary = salary;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Double getSalary() {
return salary;
}
public void setSalary(Double age) {
this.salary = salary;
}
}
}

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package com.baeldung.objecttomap;
import static org.junit.Assert.assertEquals;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.common.reflect.TypeToken;
import com.google.gson.Gson;
import org.junit.Test;
import java.lang.reflect.Field;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.SortedMap;
import java.util.TreeMap;
import java.util.stream.Collectors;
public class ObjectToMapUnitTest {
Employee employee = new Employee("John", 3000.0);
@Test
public void givenJavaObject_whenUsingReflection_thenConvertToMap() throws IllegalAccessException {
Map<String, Object> map = convertUsingReflection(employee);
assertEquals(employee.getName(), map.get("name"));
assertEquals(employee.getSalary(), map.get("salary"));
}
private Map<String, Object> convertUsingReflection(Object object) throws IllegalAccessException {
Map<String, Object> map = new HashMap<>();
Field[] fields = object.getClass().getDeclaredFields();
for (Field field : fields) {
field.setAccessible(true);
map.put(field.getName(), field.get(object));
}
return map;
}
@Test
public void givenJavaObject_whenUsingJackson_thenConvertToMap() {
ObjectMapper objectMapper = new ObjectMapper();
Map<String, Object> map = objectMapper.convertValue(employee, new TypeReference<Map<String, Object>>() {});
assertEquals(employee.getName(), map.get("name"));
assertEquals(employee.getSalary(), map.get("salary"));
}
@Test
public void givenJavaObject_whenUsingGson_thenConvertToMap() {
Gson gson = new Gson();
String json = gson.toJson(employee);
Map<String, Object> map = gson.fromJson(json, new TypeToken<Map<String, Object>>() {}.getType());
assertEquals(employee.getName(), map.get("name"));
assertEquals(employee.getSalary(), map.get("salary"));
}
@Test
public void given_UnsortedMap_whenSortingByValueDescending_thenValuesAreInDescendingOrder() {
Map<String, Integer> unsortedMap = new HashMap<>();
unsortedMap.put("one", 1);
unsortedMap.put("three", 3);
unsortedMap.put("five", 5);
unsortedMap.put("two", 2);
unsortedMap.put("four", 4);
Map<String, Integer> sortedMap = sortMapByValueDescending(unsortedMap);
assertEquals(5, sortedMap.size());
final Iterator<Integer> iterator = sortedMap.values().iterator();
assertEquals(5, (int) iterator.next());
assertEquals(4, (int) iterator.next());
assertEquals(3, (int) iterator.next());
assertEquals(2, (int) iterator.next());
assertEquals(1, (int) iterator.next());
}
@Test
public void given_UnsortedMap_whenUsingTreeMap_thenKeysAreInDescendingOrder() {
SortedMap<String, Integer> treeMap = new TreeMap<>(Comparator.reverseOrder());
treeMap.put("one", 1);
treeMap.put("three", 3);
treeMap.put("five", 5);
treeMap.put("two", 2);
treeMap.put("four", 4);
assertEquals(5, treeMap.size());
final Iterator<String> iterator = treeMap.keySet().iterator();
assertEquals("two", iterator.next());
assertEquals("three", iterator.next());
assertEquals("one", iterator.next());
assertEquals("four", iterator.next());
assertEquals("five", iterator.next());
}
private static class Employee {
private String name;
private Double salary;
public Employee(String name, Double salary) {
this.name = name;
this.salary = salary;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Double getSalary() {
return salary;
}
public void setSalary(Double age) {
this.salary = salary;
}
}
public static <K, V extends Comparable<? super V>> Map<K, V> sortMapByValueDescending(Map<K, V> map) {
return map.entrySet().stream()
.sorted(Map.Entry.<K, V>comparingByValue().reversed())
.collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, (e1, e2) -> e1, LinkedHashMap::new));
}
}

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@ -0,0 +1 @@
## Relevant Articles

View File

@ -0,0 +1,78 @@
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>core-java-collections-maps-7</artifactId>
<name>core-java-collections-maps-7</name>
<packaging>jar</packaging>
<parent>
<artifactId>core-java-modules</artifactId>
<groupId>com.baeldung.core-java-modules</groupId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<properties>
<spring.version>5.2.5.RELEASE</spring.version>
</properties>
<dependencies>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.12.4</version>
</dependency>
<dependency>
<groupId>org.openjdk.jmh</groupId>
<artifactId>jmh-core</artifactId>
<version>1.36</version>
</dependency>
<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
<version>2.8.9</version>
</dependency>
<dependency>
<groupId>org.json</groupId>
<artifactId>json</artifactId>
<version>20230227</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter</artifactId>
<version>5.8.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter</artifactId>
<version>5.8.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter</artifactId>
<version>5.8.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13.1</version>
<scope>test</scope>
</dependency>
</dependencies>
</project>

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@ -0,0 +1,60 @@
package com.baeldung.map;
import java.util.HashMap;
import java.util.Map;
public class ConvertHashMapStringToHashMapObjectUsingtoString {
public String name;
public int age;
public ConvertHashMapStringToHashMapObjectUsingtoString(String name, int age) {
this.name = name;
this.age = age;
}
public static ConvertHashMapStringToHashMapObjectUsingtoString deserializeCustomObject(String valueString) {
if (valueString.startsWith("{") && valueString.endsWith("}")) {
valueString = valueString.substring(1, valueString.length() - 1);
String[] parts = valueString.split(",");
String name = null;
int age = -1;
for (String part : parts) {
String[] keyValue = part.split("=");
if (keyValue.length == 2) {
String key = keyValue[0].trim();
String val = keyValue[1].trim();
if (key.equals("name")) {
name = val;
} else if (key.equals("age")) {
age = Integer.parseInt(val);
}
}
}
if (name != null && age >= 0) {
return new ConvertHashMapStringToHashMapObjectUsingtoString(name, age);
}
}
return new ConvertHashMapStringToHashMapObjectUsingtoString("", -1);
}
public static void main(String[] args) {
String hashMapString = "{key1={name=John, age=30}, key2={name=Alice, age=25}}";
String keyValuePairs = hashMapString.replaceAll("[{}\\s]", "");
String[] pairs = keyValuePairs.split(",");
Map<String, ConvertHashMapStringToHashMapObjectUsingtoString> actualHashMap = new HashMap<>();
for (String pair : pairs) {
String[] keyValue = pair.split("=");
if (keyValue.length == 2) {
String key = keyValue[0];
ConvertHashMapStringToHashMapObjectUsingtoString value = deserializeCustomObject(keyValue[1]);
actualHashMap.put(key, value);
}
}
System.out.println(actualHashMap);
}
@Override
public String toString() {
return "{name=" + name + ", age=" + age + "}";
}
}

View File

@ -0,0 +1,31 @@
package com.baeldung.map;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertEquals;
class ConvertHashMapStringToHashMapObjectUsingtoStringUnitTest {
@Test
void givenValidCustomObject_whenSerializing_thenSerializedStringIsCorrect() {
ConvertHashMapStringToHashMapObjectUsingtoString customObject = new ConvertHashMapStringToHashMapObjectUsingtoString("John", 30);
String expectedSerializedString = "{name=John, age=30}";
assertEquals(expectedSerializedString, customObject.toString());
}
@Test
void givenValidSerializedString_whenDeserializing_thenCustomObjectIsCorrect() {
String serializedString = "{name=Alice, age=25}";
ConvertHashMapStringToHashMapObjectUsingtoString customObject = ConvertHashMapStringToHashMapObjectUsingtoString.deserializeCustomObject(serializedString);
assertEquals("Alice", customObject.name);
assertEquals(25, customObject.age);
}
@Test
void givenInvalidSerializedString_whenDeserializing_thenDefaultCustomObjectIsCreated() {
String invalidSerializedString = "{invalidString}";
ConvertHashMapStringToHashMapObjectUsingtoString customObject = ConvertHashMapStringToHashMapObjectUsingtoString.deserializeCustomObject(invalidSerializedString);
assertEquals("", customObject.name);
assertEquals(-1, customObject.age);
}
}

View File

@ -12,10 +12,10 @@ public class EpochTimeToLocalDateTimeConverterUnitTest {
@Test
public void testConvertEpochTimeToLocalDateTime() {
long epochTimeMillis = 1624962431000L; // Example epoch time in milliseconds
LocalDateTime expectedDateTime = LocalDateTime.of(2021, 6, 29, 12, 13, 51);
LocalDateTime expectedDateTime = LocalDateTime.of(2021, 6, 29, 10, 27, 11);
Instant instant = Instant.ofEpochMilli(epochTimeMillis);
ZoneId zoneId = ZoneId.systemDefault();
ZoneId zoneId = ZoneId.of("UTC");
LocalDateTime actualDateTime = instant.atZone(zoneId).toLocalDateTime();
assertEquals(expectedDateTime, actualDateTime);

View File

@ -3,4 +3,4 @@
### Relevant Articles:
- [Introduction to Javadoc](http://www.baeldung.com/javadoc)
- [Code Snippets in Java API Documentation](https://www.baeldung.com/java-doc-code-snippets)

View File

@ -0,0 +1,18 @@
package com.baeldung.snippettag;
/**
*
* External code snippet showing the loop process in binary search method.
* {@snippet class="BinarySearch" region="binary"}
*
* Time Zone
* {@snippet file="application.properties" region="zone"}
*
*/
public class GreetingsExternalSnippet {
public void helloBinarySearch() {
System.out.println("Hi, it's great knowing that binary search uses a loop under the hood");
}
}

View File

@ -0,0 +1,35 @@
package com.baeldung.snippettag;
/**
* The code below shows a full highlighted line
* {@snippet :
* public void helloBaeldung() {
* System.out.println("Hello From Team Baeldung"); // @highlight
* }
* }
*
* highlighting a substring
* {@snippet :
* public void helloBaeldung() {
* System.out.println("Hello From Team Baeldung"); // @highlight substring="println"
* }
* }
*
* highlighting texts on multiple lines
* {@snippet :
* public void helloBaeldung() {
* System.out.println("Hello From Team Baeldung"); // @highlight region substring="println"
* String country = "USA";
* System.out.println("Hello From Team " + country); // @end
* }
* }
*
*/
public class GreetingsHighlightTag {
public void helloBaeldung() {
System.out.println("Hello From Team Baeldung");
}
}

View File

@ -0,0 +1,17 @@
package com.baeldung.snippettag;
/**
* The code below shows the content of {@code helloBaeldung()} method
* {@snippet :
* public void helloBaeldung() {
* System.out.println("Hello From Team Baeldung");
* }
* }
*/
public class GreetingsInlineSnippet {
public void helloBaeldung() {
System.out.println("Hello From Team Baeldung");
}
}

View File

@ -0,0 +1,24 @@
package com.baeldung.snippettag;
/**
*
* Using the replace tag
* {@snippet :
* public void helloBaeldung() {
* System.out.println("Hello From Team Baeldung"); // @replace regex='".*"' replacement="..."
* }
* }
* Using the link tag
* {@snippet :
* public void helloBaeldung() {
* System.out.println("Hello From Team Baeldung"); // @link substring="System.out" target="System#out"
* }
* }
*
*/
public class GreetingsReplaceAndLinkTag {
public void helloBaeldung() {
System.out.println("Hello From Team Baeldung");
}
}

View File

@ -0,0 +1,27 @@
public class BinarySearch {
public int search(int[] list, int item) {
int index = Integer.MAX_VALUE;
int low = 0;
int high = list.length - 1;
// @start region="binary"
while (low <= high) {
int mid = high - low;
int guess = list[mid];
if (guess == item) {
index = mid;
break;
} else if (guess > item) {
low = mid - 1;
} else {
low = mid + 1;
}
low++;
}
// @end region="binary"
return index;
}
}

View File

@ -0,0 +1,4 @@
# @start region="zone"
local.timezone = GMT+1
local.zip = 94123
# @end region="zone"

View File

@ -0,0 +1,2 @@
test-link*
0.*

View File

@ -0,0 +1,8 @@
## Core Java IO
This module contains articles about core Java input and output (IO)
### Relevant Articles:
- [Get File Extension From MIME Type in Java](https://www.baeldung.com/java-mime-type-file-extension)
- [[<-- Prev]](/core-java-modules/core-java-io-4)

View File

@ -0,0 +1,66 @@
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>core-java-io-5</artifactId>
<name>core-java-io-5</name>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung.core-java-modules</groupId>
<artifactId>core-java-modules</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<dependencies>
<!-- Mime Type Resolution Libraries -->
<dependency>
<groupId>org.apache.tika</groupId>
<artifactId>tika-core</artifactId>
<version>${tika.version}</version>
</dependency>
<dependency>
<groupId>net.sf.jmimemagic</groupId>
<artifactId>jmimemagic</artifactId>
<version>${jmime-magic.version}</version>
</dependency>
<dependency>
<groupId>org.jodd</groupId>
<artifactId>jodd-util</artifactId>
<version>${jodd-util.version}</version>
</dependency>
<dependency>
<groupId>com.j256.simplemagic</groupId>
<artifactId>simplemagic</artifactId>
<version>${simplemagic.version}</version>
</dependency>
</dependencies>
<build>
<finalName>core-java-io-5</finalName>
<resources>
<resource>
<directory>src/main/resources</directory>
<filtering>true</filtering>
</resource>
</resources>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>11</source>
<target>11</target>
</configuration>
</plugin>
</plugins>
</build>
<properties>
<!-- Mime Type Libraries -->
<tika.version>2.8.0</tika.version>
<jmime-magic.version>0.1.5</jmime-magic.version>
<jodd-util.version>6.2.1</jodd-util.version>
<simplemagic.version>1.17</simplemagic.version>
</properties>
</project>

View File

@ -11,10 +11,8 @@ import java.util.Map;
import java.util.Set;
import org.apache.tika.mime.MimeTypeException;
import org.junit.Test;
import com.j256.simplemagic.ContentType;
import org.junit.Test;
public class ExtensionFromMimeTypeUnitTest {
private static final String IMAGE_JPEG_MIME_TYPE = "image/jpeg";
@ -37,14 +35,14 @@ public class ExtensionFromMimeTypeUnitTest {
}
@Test
public void whenUsingMimetypesFileTypeMap_thenGetFileExtension() {
public void whenUsingSimpleMagic_thenGetFileExtension() {
List<String> expectedExtensions = Arrays.asList("jpeg", "jpg", "jpe");
String[] detectedExtensions = ContentType.fromMimeType(IMAGE_JPEG_MIME_TYPE).getFileExtensions();
assertThat(detectedExtensions).containsExactlyElementsOf(expectedExtensions);
}
@Test
public void whenUsingCustomLogic_thenGetFileExtension() {
public void whenUsingCustomMap_thenGetFileExtension() {
Map<String, Set<String>> mimeExtensionsMap = new HashMap<>();
List<String> expectedExtensions = Arrays.asList(".jpg", ".jpe", ".jpeg");
addMimeExtensions(mimeExtensionsMap, "image/jpeg", ".jpg");

View File

@ -0,0 +1,72 @@
package com.baeldung.rmlinebreaks;
import org.junit.jupiter.api.Test;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.List;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNotEquals;
public class RemoveLinebreaksUnitTest {
private Path file1Path() throws Exception {
return Paths.get(this.getClass().getClassLoader().getResource("multiple-line-1.txt").toURI());
}
private Path file2Path() throws Exception {
return Paths.get(this.getClass().getClassLoader().getResource("multiple-line-2.txt").toURI());
}
@Test
void whenRemovingLineSeparatorFromFile1_thenGetTheExpectedResult() throws Exception {
String content = Files.readString(file1Path(), StandardCharsets.UTF_8);
String result = content.replace(System.getProperty("line.separator"), "");
assertEquals("A, B, C, D, E, F", result);
}
@Test
void whenRemovingLineSeparatorFromFile2_thenNotGetTheExpectedResult() throws Exception {
String content = Files.readString(file2Path(), StandardCharsets.UTF_8);
String result = content.replace(System.getProperty("line.separator"), "");
assertNotEquals("A, B, C, D, E, F", result); // <-- NOT equals assertion!
}
@Test
void whenRemovingAllLinebreaks_thenGetTheExpectedResult() throws Exception {
String content1 = Files.readString(file1Path(), StandardCharsets.UTF_8);
// file contains CRLF
String content2 = Files.readString(file2Path(), StandardCharsets.UTF_8);
String result1 = content1.replace("\r", "").replace("\n", "");
String result2 = content2.replace("\r", "").replace("\n", "");
assertEquals("A, B, C, D, E, F", result1);
assertEquals("A, B, C, D, E, F", result2);
String resultReplaceAll = content2.replaceAll("[\\n\\r]", "");
assertEquals("A, B, C, D, E, F", resultReplaceAll);
}
@Test
void whenUsingReadAllLinesAndJoin_thenGetExpectedResult() throws Exception {
List<String> lines1 = Files.readAllLines(file1Path(), StandardCharsets.UTF_8);
// file contains CRLF
List<String> lines2 = Files.readAllLines(file2Path(), StandardCharsets.UTF_8);
String result1 = String.join("", lines1);
String result2 = String.join("", lines2);
assertEquals("A, B, C, D, E, F", result1);
assertEquals("A, B, C, D, E, F", result2);
}
}

View File

@ -0,0 +1,6 @@
A,
B,
C,
D,
E,
F

View File

@ -0,0 +1,4 @@
A, B,
C,
D, E,
F

View File

@ -7,3 +7,4 @@ This module contains articles about core Java input/output(IO) APIs.
- [Get the Desktop Path in Java](https://www.baeldung.com/java-desktop-path)
- [Check if a File Is Empty in Java](https://www.baeldung.com/java-check-file-empty)
- [Converting Relative to Absolute Paths in Java](https://www.baeldung.com/java-from-relative-to-absolute-paths)
- [Detect EOF in Java](https://www.baeldung.com/java-file-detect-end-of-file)

View File

@ -43,17 +43,6 @@
<version>${angus-activation.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.jodd</groupId>
<artifactId>jodd-util</artifactId>
<version>${jodd-util.version}</version>
</dependency>
<dependency>
<groupId>com.j256.simplemagic</groupId>
<artifactId>simplemagic</artifactId>
<version>${simplemagic.version}</version>
</dependency>
</dependencies>
<build>
@ -153,8 +142,6 @@
<fscontext.version>4.4.2</fscontext.version>
<jakarta-activation-api.version>2.1.2</jakarta-activation-api.version>
<angus-activation.version>2.0.1</angus-activation.version>
<jodd-util.version>6.2.1</jodd-util.version>
<simplemagic.version>1.17</simplemagic.version>
</properties>
</project>

View File

@ -18,7 +18,11 @@
<artifactId>mapstruct</artifactId>
<version>${mapstruct.version}</version>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>${commons-lang3.version}</version>
</dependency>
</dependencies>
<build>
<plugins>

View File

@ -0,0 +1,47 @@
package com.baeldung.compareobjects;
import java.util.Objects;
public class Address {
private String streetAddress;
private String city;
private String postalCode;
public Address(String streetAddress, String city, String postalCode) {
this.streetAddress = streetAddress;
this.city = city;
this.postalCode = postalCode;
}
public String getStreetAddress() {
return streetAddress;
}
public String getCity() {
return city;
}
public String getPostalCode() {
return postalCode;
}
@Override
public String toString() {
return "Address{" + "streetAddress='" + streetAddress + '\'' + ", city='" + city + '\'' + ", postalCode='" + postalCode + '\'' + '}';
}
@Override
public boolean equals(Object o) {
if (this == o)
return true;
if (o == null || getClass() != o.getClass())
return false;
Address address = (Address) o;
return Objects.equals(streetAddress, address.streetAddress) && Objects.equals(city, address.city) && Objects.equals(postalCode, address.postalCode);
}
@Override
public int hashCode() {
return Objects.hash(streetAddress, city, postalCode);
}
}

View File

@ -0,0 +1,58 @@
package com.baeldung.compareobjects;
import java.util.List;
import java.util.Objects;
import org.apache.commons.lang3.builder.DiffExclude;
public class Person {
private String firstName;
private String lastName;
private int age;
private List<PhoneNumber> phoneNumbers;
@DiffExclude
private Address address;
public Person(String firstName, String lastName, int age, List<PhoneNumber> phoneNumbers, Address address) {
this.firstName = firstName;
this.lastName = lastName;
this.age = age;
this.phoneNumbers = phoneNumbers;
this.address = address;
}
public String getFirstName() {
return firstName;
}
public String getLastName() {
return lastName;
}
public int getAge() {
return age;
}
public List<PhoneNumber> getPhoneNumbers() {
return phoneNumbers;
}
public Address getAddress() {
return address;
}
@Override
public boolean equals(Object o) {
if (this == o)
return true;
if (o == null || getClass() != o.getClass())
return false;
Person person = (Person) o;
return age == person.age && Objects.equals(firstName, person.firstName) && Objects.equals(lastName, person.lastName) && Objects.equals(phoneNumbers, person.phoneNumbers) && Objects.equals(address, person.address);
}
@Override
public int hashCode() {
return Objects.hash(firstName, lastName, age, phoneNumbers, address);
}
}

View File

@ -0,0 +1,32 @@
package com.baeldung.compareobjects;
import org.apache.commons.lang3.builder.DiffBuilder;
import org.apache.commons.lang3.builder.DiffResult;
import org.apache.commons.lang3.builder.ToStringStyle;
public class PersonDiffBuilder {
public static DiffResult compare(Person first, Person second) {
DiffBuilder diffBuilder = new DiffBuilder(first, second, ToStringStyle.DEFAULT_STYLE).append("person", first.getFirstName(), second.getFirstName())
.append("lastName", first.getLastName(), second.getLastName())
.append("streetAddress", first.getAddress()
.getStreetAddress(), second.getAddress()
.getStreetAddress())
.append("city", first.getAddress()
.getCity(), second.getAddress()
.getCity())
.append("postalCode", first.getAddress()
.getPostalCode(), second.getAddress()
.getPostalCode())
.append("age", first.getAge(), second.getAge());
for (int i = 0; i < first.getPhoneNumbers()
.size(); i++) {
diffBuilder.append("phoneNumbers[" + i + "].number", first.getPhoneNumbers()
.get(i)
.getNumber(), second.getPhoneNumbers()
.get(i)
.getNumber());
}
return diffBuilder.build();
}
}

View File

@ -0,0 +1,11 @@
package com.baeldung.compareobjects;
import org.apache.commons.lang3.builder.DiffResult;
import org.apache.commons.lang3.builder.ReflectionDiffBuilder;
import org.apache.commons.lang3.builder.ToStringStyle;
public class PersonReflectionDiffBuilder {
public static DiffResult compare(Person first, Person second) {
return new ReflectionDiffBuilder<>(first, second, ToStringStyle.SHORT_PREFIX_STYLE).build();
}
}

View File

@ -0,0 +1,43 @@
package com.baeldung.compareobjects;
import java.util.Objects;
import org.apache.commons.lang3.builder.DiffExclude;
public class PhoneNumber {
private String type;
private String number;
public PhoneNumber(String type, String number) {
this.type = type;
this.number = number;
}
public String getType() {
return type;
}
public String getNumber() {
return number;
}
@Override
public String toString() {
return "PhoneNumber{" + "type='" + type + '\'' + ", number='" + number + '\'' + '}';
}
@Override
public boolean equals(Object o) {
if (this == o)
return true;
if (o == null || getClass() != o.getClass())
return false;
PhoneNumber that = (PhoneNumber) o;
return Objects.equals(number, that.number);
}
@Override
public int hashCode() {
return Objects.hash(number);
}
}

View File

@ -0,0 +1,38 @@
package com.baeldung.compareobjects;
import static org.junit.jupiter.api.Assertions.assertFalse;
import java.util.ArrayList;
import java.util.List;
import org.apache.commons.lang3.builder.Diff;
import org.apache.commons.lang3.builder.DiffResult;
import org.junit.jupiter.api.Test;
public class PersonDiffBuilderUnitTest {
@Test
void givenTwoPeopleDifferent_whenComparingWithDiffBuilder_thenDifferencesFound() {
List<PhoneNumber> phoneNumbers1 = new ArrayList<>();
phoneNumbers1.add(new PhoneNumber("home", "123-456-7890"));
phoneNumbers1.add(new PhoneNumber("work", "987-654-3210"));
List<PhoneNumber> phoneNumbers2 = new ArrayList<>();
phoneNumbers2.add(new PhoneNumber("mobile1", "123-456-7890"));
phoneNumbers2.add(new PhoneNumber("mobile2", "987-654-3210"));
Address address1 = new Address("123 Main St", "London", "12345");
Address address2 = new Address("123 Main St", "Paris", "54321");
Person person1 = new Person("John", "Doe", 30, phoneNumbers1, address1);
Person person2 = new Person("Jane", "Smith", 28, phoneNumbers2, address2);
DiffResult<Person> diff = PersonDiffBuilder.compare(person1, person2);
for (Diff<?> d : diff.getDiffs()) {
System.out.println(d.getFieldName() + ": " + d.getLeft() + " != " + d.getRight());
}
assertFalse(diff.getDiffs()
.isEmpty());
}
}

View File

@ -0,0 +1,37 @@
package com.baeldung.compareobjects;
import static org.junit.jupiter.api.Assertions.assertFalse;
import java.util.ArrayList;
import java.util.List;
import org.apache.commons.lang3.builder.Diff;
import org.apache.commons.lang3.builder.DiffResult;
import org.junit.jupiter.api.Test;
public class PersonReflectionDiffBuilderUnitTest {
@Test
void givenTwoPeopleDifferent_whenComparingWithReflectionDiffBuilder_thenDifferencesFound() {
List<PhoneNumber> phoneNumbers1 = new ArrayList<>();
phoneNumbers1.add(new PhoneNumber("home", "123-456-7890"));
phoneNumbers1.add(new PhoneNumber("work", "987-654-3210"));
List<PhoneNumber> phoneNumbers2 = new ArrayList<>();
phoneNumbers2.add(new PhoneNumber("mobile1", "123-456-7890"));
phoneNumbers2.add(new PhoneNumber("mobile2", "987-654-3210"));
Address address1 = new Address("123 Main St", "London", "12345");
Address address2 = new Address("123 Main St", "Paris", "54321");
Person person1 = new Person("John", "Doe", 30, phoneNumbers1, address1);
Person person2 = new Person("Jane", "Smith", 28, phoneNumbers2, address2);
DiffResult<Person> diff = PersonReflectionDiffBuilder.compare(person1, person2);
for (Diff<?> d : diff.getDiffs()) {
System.out.println(d.getFieldName() + ": " + d.getLeft() + " != " + d.getRight());
}
assertFalse(diff.getDiffs()
.isEmpty());
}
}

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