Merge branch 'eugenp:master' into master

algorithms-miscellaneous-2/src/test/java/com/baeldung/algorithms/astar/RouteFinder.java

@@ -8,6 +8,9 @@ import java.util.PriorityQueue;
 import java.util.Queue;
 import java.util.stream.Collectors;
 
+import lombok.extern.slf4j.Slf4j;
+
+@Slf4j
 public class RouteFinder<T extends GraphNode> {
     private final Graph<T> graph;
     private final Scorer<T> nextNodeScorer;
@@ -28,11 +31,11 @@ public class RouteFinder<T extends GraphNode> {
         openSet.add(start);
 
         while (!openSet.isEmpty()) {
-            System.out.println("Open Set contains: " + openSet.stream().map(RouteNode::getCurrent).collect(Collectors.toSet()));
+            log.debug("Open Set contains: " + openSet.stream().map(RouteNode::getCurrent).collect(Collectors.toSet()));
             RouteNode<T> next = openSet.poll();
-            System.out.println("Looking at node: " + next);
+            log.debug("Looking at node: " + next);
             if (next.getCurrent().equals(to)) {
-                System.out.println("Found our destination!");
+                log.debug("Found our destination!");
 
                 List<T> route = new ArrayList<>();
                 RouteNode<T> current = next;
@@ -41,7 +44,7 @@ public class RouteFinder<T extends GraphNode> {
                     current = allNodes.get(current.getPrevious());
                 } while (current != null);
 
-                System.out.println("Route: " + route);
+                log.debug("Route: " + route);
                 return route;
             }
 
@@ -55,7 +58,7 @@ public class RouteFinder<T extends GraphNode> {
                     nextNode.setRouteScore(newScore);
                     nextNode.setEstimatedScore(newScore + targetScorer.computeCost(connection, to));
                     openSet.add(nextNode);
-                    System.out.println("Found a better route to node: " + nextNode);
+                    log.debug("Found a better route to node: " + nextNode);
                 }
             });
         }

algorithms-miscellaneous-2/src/test/java/com/baeldung/algorithms/astar/underground/RouteFinderIntegrationTest.java

@@ -1,5 +1,7 @@
 package com.baeldung.algorithms.astar.underground;
 
+import static org.assertj.core.api.Assertions.assertThat;
+
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
@@ -10,9 +12,13 @@ import java.util.stream.Stream;
 
 import com.baeldung.algorithms.astar.Graph;
 import com.baeldung.algorithms.astar.RouteFinder;
+
+import lombok.extern.slf4j.Slf4j;
+
 import org.junit.Before;
 import org.junit.Test;
 
+@Slf4j
 public class RouteFinderIntegrationTest {
 
     private Graph<Station> underground;
@@ -637,7 +643,8 @@ public class RouteFinderIntegrationTest {
     @Test
     public void findRoute() {
         List<Station> route = routeFinder.findRoute(underground.getNode("74"), underground.getNode("7"));
+        assertThat(route).size().isPositive();
 
-        System.out.println(route.stream().map(Station::getName).collect(Collectors.toList()));
+        route.stream().map(Station::getName).collect(Collectors.toList()).forEach(station -> log.debug(station));
     }
 }

apache-kafka/README.md

@@ -0,0 +1,18 @@
+## Apache Kafka
+
+This module contains articles about Apache Kafka.
+
+### Relevant articles
+- [Kafka Streams vs Kafka Consumer](https://www.baeldung.com/java-kafka-streams-vs-kafka-consumer)
+- [Kafka Topic Creation Using Java](https://www.baeldung.com/kafka-topic-creation)
+- [Using Kafka MockConsumer](https://www.baeldung.com/kafka-mockconsumer)
+- [Using Kafka MockProducer](https://www.baeldung.com/kafka-mockproducer)
+- [Introduction to KafkaStreams in Java](https://www.baeldung.com/java-kafka-streams)
+- [Introduction to Kafka Connectors](https://www.baeldung.com/kafka-connectors-guide)
+- [Kafka Connect Example with MQTT and MongoDB](https://www.baeldung.com/kafka-connect-mqtt-mongodb)
+- [Building a Data Pipeline with Flink and Kafka](https://www.baeldung.com/kafka-flink-data-pipeline)
+- [Exactly Once Processing in Kafka with Java](https://www.baeldung.com/kafka-exactly-once)
+
+
+##### Building the project
+You can build the project from the command line using: *mvn clean install*, or in an IDE.

apache-kafka/pom.xml

@@ -0,0 +1,180 @@
+<?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>apache-kafka</artifactId>
+    <name>apache-kafka</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.kafka</groupId>
+            <artifactId>kafka-clients</artifactId>
+            <version>${kafka.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.kafka</groupId>
+            <artifactId>kafka-streams</artifactId>
+            <version>${kafka.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-api</artifactId>
+            <version>${org.slf4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-log4j12</artifactId>
+            <version>${org.slf4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.flink</groupId>
+            <artifactId>flink-connector-kafka-0.11_2.11</artifactId>
+            <version>${flink.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.flink</groupId>
+            <artifactId>flink-streaming-java_2.11</artifactId>
+            <version>${flink.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.flink</groupId>
+            <artifactId>flink-core</artifactId>
+            <version>${flink.version}</version>
+            <exclusions>
+                <exclusion>
+                    <artifactId>commons-logging</artifactId>
+                    <groupId>commons-logging</groupId>
+                </exclusion>
+            </exclusions>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.flink</groupId>
+            <artifactId>flink-java</artifactId>
+            <version>${flink.version}</version>
+            <exclusions>
+                <exclusion>
+                    <artifactId>commons-logging</artifactId>
+                    <groupId>commons-logging</groupId>
+                </exclusion>
+            </exclusions>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.flink</groupId>
+            <artifactId>flink-test-utils_2.11</artifactId>
+            <version>${flink.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>${guava.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.awaitility</groupId>
+            <artifactId>awaitility</artifactId>
+            <version>${awaitility.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.awaitility</groupId>
+            <artifactId>awaitility-proxy</artifactId>
+            <version>${awaitility.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.datatype</groupId>
+            <artifactId>jackson-datatype-jsr310</artifactId>
+            <version>${jackson.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+            <version>${jackson.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.testcontainers</groupId>
+            <artifactId>kafka</artifactId>
+            <version>${testcontainers-kafka.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.testcontainers</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>${testcontainers-jupiter.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.spark</groupId>
+            <artifactId>spark-core_2.11</artifactId>
+            <version>${org.apache.spark.spark-core.version}</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.spark</groupId>
+            <artifactId>spark-sql_2.11</artifactId>
+            <version>${org.apache.spark.spark-core.version}</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.spark</groupId>
+            <artifactId>spark-graphx_2.11</artifactId>
+            <version>${org.apache.spark.spark-core.version}</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.spark</groupId>
+            <artifactId>spark-streaming_2.11</artifactId>
+            <version>${org.apache.spark.spark-core.version}</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.spark</groupId>
+            <artifactId>spark-mllib_2.11</artifactId>
+            <version>${org.apache.spark.spark-core.version}</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.spark</groupId>
+            <artifactId>spark-streaming-kafka-0-10_2.11</artifactId>
+            <version>${org.apache.spark.spark-core.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.datastax.spark</groupId>
+            <artifactId>spark-cassandra-connector_2.11</artifactId>
+            <version>${com.datastax.spark.spark-cassandra-connector.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.datastax.spark</groupId>
+            <artifactId>spark-cassandra-connector-java_2.11</artifactId>
+            <version>${com.datastax.spark.spark-cassandra-connector-java.version}</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <assertj.version>3.6.2</assertj.version>
+        <kafka.version>2.8.0</kafka.version>
+        <testcontainers-kafka.version>1.15.3</testcontainers-kafka.version>
+        <testcontainers-jupiter.version>1.15.3</testcontainers-jupiter.version>
+        <flink.version>1.5.0</flink.version>
+        <awaitility.version>3.0.0</awaitility.version>
+        <guava.version>29.0-jre</guava.version>
+        <org.apache.spark.spark-core.version>2.4.8</org.apache.spark.spark-core.version>
+        <graphframes.version>0.8.1-spark3.0-s_2.12</graphframes.version>
+        <com.datastax.spark.spark-cassandra-connector.version>2.5.2</com.datastax.spark.spark-cassandra-connector.version>
+        <com.datastax.spark.spark-cassandra-connector-java.version>1.6.0-M1</com.datastax.spark.spark-cassandra-connector-java.version>
+    </properties>
+
+</project>

apache-kafka/src/main/java/com/baeldung/flink/FlinkDataPipeline.java

@@ -0,0 +1,70 @@
+package com.baeldung.flink;
+
+import com.baeldung.flink.model.Backup;
+import com.baeldung.flink.model.InputMessage;
+import com.baeldung.flink.operator.BackupAggregator;
+import com.baeldung.flink.operator.InputMessageTimestampAssigner;
+import com.baeldung.flink.operator.WordsCapitalizer;
+import org.apache.flink.streaming.api.TimeCharacteristic;
+import org.apache.flink.streaming.api.datastream.DataStream;
+import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
+import org.apache.flink.streaming.api.windowing.time.Time;
+import org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumer011;
+import org.apache.flink.streaming.connectors.kafka.FlinkKafkaProducer011;
+
+import static com.baeldung.flink.connector.Consumers.*;
+import static com.baeldung.flink.connector.Producers.*;
+
+public class FlinkDataPipeline {
+
+    public static void capitalize() throws Exception {
+        String inputTopic = "flink_input";
+        String outputTopic = "flink_output";
+        String consumerGroup = "baeldung";
+        String address = "localhost:9092";
+
+        StreamExecutionEnvironment environment = StreamExecutionEnvironment.getExecutionEnvironment();
+
+        FlinkKafkaConsumer011<String> flinkKafkaConsumer = createStringConsumerForTopic(inputTopic, address, consumerGroup);
+        flinkKafkaConsumer.setStartFromEarliest();
+
+        DataStream<String> stringInputStream = environment.addSource(flinkKafkaConsumer);
+
+        FlinkKafkaProducer011<String> flinkKafkaProducer = createStringProducer(outputTopic, address);
+
+        stringInputStream.map(new WordsCapitalizer())
+            .addSink(flinkKafkaProducer);
+
+        environment.execute();
+    }
+
+    public static void createBackup() throws Exception {
+        String inputTopic = "flink_input";
+        String outputTopic = "flink_output";
+        String consumerGroup = "baeldung";
+        String kafkaAddress = "localhost:9092";
+
+        StreamExecutionEnvironment environment = StreamExecutionEnvironment.getExecutionEnvironment();
+
+        environment.setStreamTimeCharacteristic(TimeCharacteristic.EventTime);
+
+        FlinkKafkaConsumer011<InputMessage> flinkKafkaConsumer = createInputMessageConsumer(inputTopic, kafkaAddress, consumerGroup);
+        flinkKafkaConsumer.setStartFromEarliest();
+
+        flinkKafkaConsumer.assignTimestampsAndWatermarks(new InputMessageTimestampAssigner());
+        FlinkKafkaProducer011<Backup> flinkKafkaProducer = createBackupProducer(outputTopic, kafkaAddress);
+
+        DataStream<InputMessage> inputMessagesStream = environment.addSource(flinkKafkaConsumer);
+
+        inputMessagesStream.timeWindowAll(Time.hours(24))
+            .aggregate(new BackupAggregator())
+            .addSink(flinkKafkaProducer);
+
+        environment.execute();
+    }
+
+    public static void main(String[] args) throws Exception {
+        createBackup();
+    }
+
+}

apache-kafka/src/main/java/com/baeldung/flink/connector/Consumers.java

@@ -9,13 +9,11 @@ import java.util.Properties;
 
 public class Consumers {
 
-public static FlinkKafkaConsumer011<String> createStringConsumerForTopic(
+    public static FlinkKafkaConsumer011<String> createStringConsumerForTopic(String topic, String kafkaAddress, String kafkaGroup) {
-  String topic, String kafkaAddress, String kafkaGroup ) {
         Properties props = new Properties();
         props.setProperty("bootstrap.servers", kafkaAddress);
         props.setProperty("group.id", kafkaGroup);
-    FlinkKafkaConsumer011<String> consumer =
+        FlinkKafkaConsumer011<String> consumer = new FlinkKafkaConsumer011<>(topic, new SimpleStringSchema(), props);
-      new FlinkKafkaConsumer011<>(topic, new SimpleStringSchema(),props);
 
         return consumer;
     }
@@ -24,8 +22,7 @@ public static FlinkKafkaConsumer011<String> createStringConsumerForTopic(
         Properties properties = new Properties();
         properties.setProperty("bootstrap.servers", kafkaAddress);
         properties.setProperty("group.id", kafkaGroup);
-        FlinkKafkaConsumer011<InputMessage> consumer = new FlinkKafkaConsumer011<InputMessage>(
+        FlinkKafkaConsumer011<InputMessage> consumer = new FlinkKafkaConsumer011<InputMessage>(topic, new InputMessageDeserializationSchema(), properties);
-                topic, new InputMessageDeserializationSchema(),properties);
 
         return consumer;
     }

apache-kafka/src/main/java/com/baeldung/flink/model/InputMessage.java

@@ -18,6 +18,7 @@ public class InputMessage {
     public String getSender() {
         return sender;
     }
+
     public void setSender(String sender) {
         this.sender = sender;
     }
@@ -55,8 +56,10 @@ public class InputMessage {
 
     @Override
     public boolean equals(Object o) {
-        if (this == o) return true;
+        if (this == o)
-        if (o == null || getClass() != o.getClass()) return false;
+            return true;
+        if (o == null || getClass() != o.getClass())
+            return false;
         InputMessage message1 = (InputMessage) o;
         return Objects.equal(sender, message1.sender) && 
                 Objects.equal(recipient, message1.recipient) && 

apache-kafka/src/main/java/com/baeldung/flink/operator/BackupAggregator.java

@@ -0,0 +1,34 @@
+package com.baeldung.flink.operator;
+
+import com.baeldung.flink.model.Backup;
+import com.baeldung.flink.model.InputMessage;
+import org.apache.flink.api.common.functions.AggregateFunction;
+
+import java.time.LocalDateTime;
+import java.util.ArrayList;
+import java.util.List;
+
+public class BackupAggregator implements AggregateFunction<InputMessage, List<InputMessage>, Backup> {
+    @Override
+    public List<InputMessage> createAccumulator() {
+        return new ArrayList<>();
+    }
+
+    @Override
+    public List<InputMessage> add(InputMessage inputMessage, List<InputMessage> inputMessages) {
+        inputMessages.add(inputMessage);
+        return inputMessages;
+    }
+
+    @Override
+    public Backup getResult(List<InputMessage> inputMessages) {
+        Backup backup = new Backup(inputMessages, LocalDateTime.now());
+        return backup;
+    }
+
+    @Override
+    public List<InputMessage> merge(List<InputMessage> inputMessages, List<InputMessage> acc1) {
+        inputMessages.addAll(acc1);
+        return inputMessages;
+    }
+}

apache-kafka/src/main/java/com/baeldung/flink/operator/InputMessageTimestampAssigner.java

@@ -12,7 +12,9 @@ public class InputMessageTimestampAssigner implements AssignerWithPunctuatedWate
     @Override
     public long extractTimestamp(InputMessage element, long previousElementTimestamp) {
         ZoneId zoneId = ZoneId.systemDefault();
-        return element.getSentAt().atZone(zoneId).toEpochSecond() * 1000;
+        return element.getSentAt()
+            .atZone(zoneId)
+            .toEpochSecond() * 1000;
     }
 
     @Nullable

apache-kafka/src/main/java/com/baeldung/flink/schema/BackupSerializationSchema.java

@@ -9,8 +9,7 @@ import org.apache.flink.api.common.serialization.SerializationSchema;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-public class BackupSerializationSchema
+public class BackupSerializationSchema implements SerializationSchema<Backup> {
-  implements SerializationSchema<Backup> {
 
     static ObjectMapper objectMapper = new ObjectMapper().registerModule(new JavaTimeModule());
 

apache-kafka/src/main/java/com/baeldung/flink/schema/InputMessageDeserializationSchema.java

@@ -8,12 +8,10 @@ import org.apache.flink.api.common.typeinfo.TypeInformation;
 
 import java.io.IOException;
 
-public class InputMessageDeserializationSchema implements
+public class InputMessageDeserializationSchema implements DeserializationSchema<InputMessage> {
-      DeserializationSchema<InputMessage> {
 
     static ObjectMapper objectMapper = new ObjectMapper().registerModule(new JavaTimeModule());
 
-
     @Override
     public InputMessage deserialize(byte[] bytes) throws IOException {
 

apache-kafka/src/main/java/com/baeldung/kafka/admin/KafkaTopicApplication.java

@@ -27,11 +27,11 @@ public class KafkaTopicApplication {
             short replicationFactor = 1;
             NewTopic newTopic = new NewTopic(topicName, partitions, replicationFactor);
 
-            CreateTopicsResult result = admin.createTopics(
+            CreateTopicsResult result = admin.createTopics(Collections.singleton(newTopic));
-              Collections.singleton(newTopic));
 
             // get the async result for the new topic creation
-            KafkaFuture<Void> future = result.values().get(topicName);
+            KafkaFuture<Void> future = result.values()
+                .get(topicName);
 
             // call get() to block until topic creation has completed or failed
             future.get();
@@ -47,15 +47,13 @@ public class KafkaTopicApplication {
             short replicationFactor = 1;
             NewTopic newTopic = new NewTopic(topicName, partitions, replicationFactor);
 
-            CreateTopicsOptions topicOptions = new CreateTopicsOptions()
+            CreateTopicsOptions topicOptions = new CreateTopicsOptions().validateOnly(true)
-              .validateOnly(true)
                 .retryOnQuotaViolation(true);
 
-            CreateTopicsResult result = admin.createTopics(
+            CreateTopicsResult result = admin.createTopics(Collections.singleton(newTopic), topicOptions);
-              Collections.singleton(newTopic), topicOptions
-            );
 
-            KafkaFuture<Void> future = result.values().get(topicName);
+            KafkaFuture<Void> future = result.values()
+                .get(topicName);
             future.get();
         }
     }
@@ -72,14 +70,12 @@ public class KafkaTopicApplication {
             Map<String, String> newTopicConfig = new HashMap<>();
             newTopicConfig.put(TopicConfig.CLEANUP_POLICY_CONFIG, TopicConfig.CLEANUP_POLICY_COMPACT);
             newTopicConfig.put(TopicConfig.COMPRESSION_TYPE_CONFIG, "lz4");
-            NewTopic newTopic = new NewTopic(topicName, partitions, replicationFactor)
+            NewTopic newTopic = new NewTopic(topicName, partitions, replicationFactor).configs(newTopicConfig);
-              .configs(newTopicConfig);
 
-            CreateTopicsResult result = admin.createTopics(
+            CreateTopicsResult result = admin.createTopics(Collections.singleton(newTopic));
-              Collections.singleton(newTopic)
-            );
 
-            KafkaFuture<Void> future = result.values().get(topicName);
+            KafkaFuture<Void> future = result.values()
+                .get(topicName);
             future.get();
         }
     }

apache-kafka/src/main/java/com/baeldung/kafka/consumer/CountryPopulationConsumer.java

@@ -19,9 +19,7 @@ public class CountryPopulationConsumer {
     private java.util.function.Consumer<Throwable> exceptionConsumer;
     private java.util.function.Consumer<CountryPopulation> countryPopulationConsumer;
 
-    public CountryPopulationConsumer(
+    public CountryPopulationConsumer(Consumer<String, Integer> consumer, java.util.function.Consumer<Throwable> exceptionConsumer, java.util.function.Consumer<CountryPopulation> countryPopulationConsumer) {
-            Consumer<String, Integer> consumer, java.util.function.Consumer<Throwable> exceptionConsumer,
-            java.util.function.Consumer<CountryPopulation> countryPopulationConsumer) {
         this.consumer = consumer;
         this.exceptionConsumer = exceptionConsumer;
         this.countryPopulationConsumer = countryPopulationConsumer;

apache-kafka/src/main/java/com/baeldung/kafka/exactlyonce/TransactionalMessageProducer.java

@@ -1,4 +1,4 @@
-package com.baeldung.kafka;
+package com.baeldung.kafka.exactlyonce;
 
 import org.apache.kafka.clients.producer.KafkaProducer;
 import org.apache.kafka.clients.producer.ProducerRecord;
@@ -28,8 +28,8 @@ public class TransactionalMessageProducer {
 
             producer.beginTransaction();
 
-            Stream.of(DATA_MESSAGE_1, DATA_MESSAGE_2).forEach(s -> producer.send(
+            Stream.of(DATA_MESSAGE_1, DATA_MESSAGE_2)
-                    new ProducerRecord<String, String>("input", null, s)));
+                .forEach(s -> producer.send(new ProducerRecord<String, String>("input", null, s)));
 
             producer.commitTransaction();
 

apache-kafka/src/main/java/com/baeldung/kafka/exactlyonce/TransactionalWordCount.java

@@ -1,4 +1,4 @@
-package com.baeldung.kafka;
+package com.baeldung.kafka.exactlyonce;
 
 import org.apache.kafka.clients.consumer.ConsumerRecord;
 import org.apache.kafka.clients.consumer.ConsumerRecords;
@@ -44,7 +44,8 @@ public class TransactionalWordCount {
 
                 Map<String, Integer> wordCountMap = records.records(new TopicPartition(INPUT_TOPIC, 0))
                     .stream()
-                        .flatMap(record -> Stream.of(record.value().split(" ")))
+                    .flatMap(record -> Stream.of(record.value()
+                        .split(" ")))
                     .map(word -> Tuple.of(word, 1))
                     .collect(Collectors.toMap(tuple -> tuple.getKey(), t1 -> t1.getValue(), (v1, v2) -> v1 + v2));
 
@@ -56,7 +57,8 @@ public class TransactionalWordCount {
 
                 for (TopicPartition partition : records.partitions()) {
                     List<ConsumerRecord<String, String>> partitionedRecords = records.records(partition);
-                    long offset = partitionedRecords.get(partitionedRecords.size() - 1).offset();
+                    long offset = partitionedRecords.get(partitionedRecords.size() - 1)
+                        .offset();
 
                     offsetsToCommit.put(partition, new OffsetAndMetadata(offset + 1));
                 }
@@ -72,7 +74,6 @@ public class TransactionalWordCount {
 
         }
 
-
     }
 
     private static KafkaConsumer<String, String> createKafkaConsumer() {

apache-kafka/src/main/java/com/baeldung/kafka/exactlyonce/Tuple.java

@@ -1,4 +1,4 @@
-package com.baeldung.kafka;
+package com.baeldung.kafka.exactlyonce;
 
 public class Tuple {
 

apache-kafka/src/main/java/com/baeldung/kafka/producer/KafkaProducer.java

@@ -15,8 +15,7 @@ public class KafkaProducer {
     }
 
     public Future<RecordMetadata> send(String key, String value) {
-        ProducerRecord record = new ProducerRecord("topic_sports_news",
+        ProducerRecord record = new ProducerRecord("topic_sports_news", key, value);
-                key, value);
         return producer.send(record);
     }
 
@@ -36,5 +35,4 @@ public class KafkaProducer {
         producer.commitTransaction();
     }
 
-
 }

apache-kafka/src/test/java/com/baeldung/kafka/streamsvsconsumer/KafkaStreamsLiveTest.java

@@ -1,4 +1,4 @@
-package com.baeldung.kafka.streams;
+package com.baeldung.kafka.streamsvsconsumer;
 
 import org.apache.kafka.clients.consumer.ConsumerConfig;
 import org.apache.kafka.clients.producer.KafkaProducer;

apache-kafka/src/test/java/com/baeldung/kafkastreams/KafkaStreamsLiveTest.java

@@ -1,23 +1,28 @@
 package com.baeldung.kafkastreams;
 
-import org.apache.kafka.clients.consumer.ConsumerConfig;
+import java.io.IOException;
-import org.apache.kafka.common.serialization.Serde;
+import java.io.UncheckedIOException;
-import org.apache.kafka.common.serialization.Serdes;
+import java.nio.file.Files;
-import org.apache.kafka.streams.KafkaStreams;
+import java.nio.file.Path;
-import org.apache.kafka.streams.StreamsConfig;
-import org.apache.kafka.streams.kstream.KStream;
-import org.apache.kafka.streams.kstream.KStreamBuilder;
-import org.apache.kafka.streams.kstream.KTable;
-import org.apache.kafka.test.TestUtils;
-import org.junit.Ignore;
-import org.junit.Test;
-
 import java.util.Arrays;
 import java.util.Properties;
 import java.util.regex.Pattern;
 
+import org.apache.kafka.clients.consumer.ConsumerConfig;
+import org.apache.kafka.common.serialization.Serdes;
+import org.apache.kafka.streams.KafkaStreams;
+import org.apache.kafka.streams.StreamsBuilder;
+import org.apache.kafka.streams.StreamsConfig;
+import org.apache.kafka.streams.Topology;
+import org.apache.kafka.streams.kstream.KStream;
+import org.apache.kafka.streams.kstream.KTable;
+import org.apache.kafka.streams.kstream.Produced;
+import org.junit.Ignore;
+import org.junit.Test;
+
 public class KafkaStreamsLiveTest {
     private String bootstrapServers = "localhost:9092";
+    private Path stateDirectory;
 
     @Test
     @Ignore("it needs to have kafka broker running on local")
@@ -28,31 +33,43 @@ public class KafkaStreamsLiveTest {
         Properties streamsConfiguration = new Properties();
         streamsConfiguration.put(StreamsConfig.APPLICATION_ID_CONFIG, "wordcount-live-test");
         streamsConfiguration.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
-        streamsConfiguration.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
+        streamsConfiguration.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String()
-        streamsConfiguration.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
+            .getClass()
+            .getName());
+        streamsConfiguration.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, Serdes.String()
+            .getClass()
+            .getName());
         streamsConfiguration.put(StreamsConfig.COMMIT_INTERVAL_MS_CONFIG, 1000);
         streamsConfiguration.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
+        
         // Use a temporary directory for storing state, which will be automatically removed after the test.
-        streamsConfiguration.put(StreamsConfig.STATE_DIR_CONFIG, TestUtils.tempDirectory().getAbsolutePath());
+        try {
+            this.stateDirectory = Files.createTempDirectory("kafka-streams");
+            streamsConfiguration.put(StreamsConfig.STATE_DIR_CONFIG, this.stateDirectory.toAbsolutePath()
+                .toString());
+        } catch (final IOException e) {
+            throw new UncheckedIOException("Cannot create temporary directory", e);
+        }
 
         // when
-        KStreamBuilder builder = new KStreamBuilder();
+        final StreamsBuilder builder = new StreamsBuilder();
         KStream<String, String> textLines = builder.stream(inputTopic);
         Pattern pattern = Pattern.compile("\\W+", Pattern.UNICODE_CHARACTER_CLASS);
 
-        KTable<String, Long> wordCounts = textLines
+        KTable<String, Long> wordCounts = textLines.flatMapValues(value -> Arrays.asList(pattern.split(value.toLowerCase())))
-                .flatMapValues(value -> Arrays.asList(pattern.split(value.toLowerCase())))
             .groupBy((key, word) -> word)
             .count();
 
-        wordCounts.foreach((word, count) -> System.out.println("word: " + word + " -> " + count));
+        wordCounts.toStream()
+            .foreach((word, count) -> System.out.println("word: " + word + " -> " + count));
 
         String outputTopic = "outputTopic";
-        final Serde<String> stringSerde = Serdes.String();
-        final Serde<Long> longSerde = Serdes.Long();
-        wordCounts.to(stringSerde, longSerde, outputTopic);
 
-        KafkaStreams streams = new KafkaStreams(builder, streamsConfiguration);
+        wordCounts.toStream()
+            .to(outputTopic, Produced.with(Serdes.String(), Serdes.Long()));
+
+        final Topology topology = builder.build();
+        KafkaStreams streams = new KafkaStreams(topology, streamsConfiguration);
         streams.start();
 
         // then

core-java-modules/core-java-12/README.md

@@ -2,3 +2,4 @@
 
 - [String API Updates in Java 12](https://www.baeldung.com/java12-string-api)
 - [New Features in Java 12](https://www.baeldung.com/java-12-new-features)
+- [Compare the Content of Two Files in Java](https://www.baeldung.com/java-compare-files)

core-java-modules/core-java-16/pom.xml

@@ -23,6 +23,11 @@
 			<version>${assertj.version}</version>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>org.apache.commons</groupId>
+			<artifactId>commons-lang3</artifactId>
+			<version>3.12.0</version>
+		</dependency>
 	</dependencies>
 
 	<build>

core-java-modules/core-java-16/src/main/java/com/baeldung/java_16_features/groupingby/BlogPost.java

@@ -0,0 +1,43 @@
+package com.baeldung.java_16_features.groupingby;
+
+import java.util.IntSummaryStatistics;
+
+
+public class BlogPost {
+    
+    private String title;
+    private String author;
+    private BlogPostType type;
+    private int likes;
+    record AuthPostTypesLikes(String author, BlogPostType type, int likes) {};
+    record PostcountTitlesLikesStats(long postCount, String titles, IntSummaryStatistics likesStats){};
+    record TitlesBoundedSumOfLikes(String titles, int boundedSumOfLikes) {};
+    
+    public BlogPost(String title, String author, BlogPostType type, int likes) {
+        this.title = title;
+        this.author = author;
+        this.type = type;
+        this.likes = likes;
+    }
+
+    public String getTitle() {
+        return title;
+    }
+
+    public String getAuthor() {
+        return author;
+    }
+
+    public BlogPostType getType() {
+        return type;
+    }
+
+    public int getLikes() {
+        return likes;
+    }
+
+    @Override
+    public String toString() {
+        return "BlogPost{" + "title='" + title + '\'' + ", type=" + type + ", likes=" + likes + '}';
+    }
+}

core-java-modules/core-java-16/src/main/java/com/baeldung/java_16_features/groupingby/BlogPostType.java

@@ -0,0 +1,5 @@
+package com.baeldung.java_16_features.groupingby;
+
+public enum BlogPostType {
+    NEWS, REVIEW, GUIDE
+}

core-java-modules/core-java-16/src/main/java/com/baeldung/java_16_features/groupingby/Tuple.java

@@ -0,0 +1,41 @@
+package com.baeldung.java_16_features.groupingby;
+
+import java.util.Objects;
+
+public class Tuple {
+    private final BlogPostType type;
+    private final String author;
+
+    public Tuple(BlogPostType type, String author) {
+        this.type = type;
+        this.author = author;
+    }
+
+    public BlogPostType getType() {
+        return type;
+    }
+
+    public String getAuthor() {
+        return author;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o)
+            return true;
+        if (o == null || getClass() != o.getClass())
+            return false;
+        Tuple tuple = (Tuple) o;
+        return type == tuple.type && author.equals(tuple.author);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(type, author);
+    }
+
+    @Override
+    public String toString() {
+        return "Tuple{" + "type=" + type + ", author='" + author + '\'' + '}';
+    }
+}

core-java-modules/core-java-16/src/test/java/com/baeldung/java_16_features/groupingby/JavaGroupingByCollectorUnitTest.java

@@ -0,0 +1,302 @@
+package com.baeldung.java_16_features.groupingby;
+
+import static java.util.Comparator.comparingInt;
+import static java.util.stream.Collectors.averagingInt;
+import static java.util.stream.Collectors.counting;
+import static java.util.stream.Collectors.groupingBy;
+import static java.util.stream.Collectors.groupingByConcurrent;
+import static java.util.stream.Collectors.collectingAndThen;
+import static java.util.stream.Collectors.toMap;
+import static java.util.stream.Collectors.joining;
+import static java.util.stream.Collectors.mapping;
+import static java.util.stream.Collectors.maxBy;
+import static java.util.stream.Collectors.summarizingInt;
+import static java.util.stream.Collectors.summingInt;
+import static java.util.stream.Collectors.toList;
+import static java.util.stream.Collectors.toSet;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.offset;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.Arrays;
+import java.util.EnumMap;
+import java.util.IntSummaryStatistics;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.concurrent.ConcurrentMap;
+
+import org.apache.commons.lang3.tuple.ImmutablePair;
+import org.apache.commons.lang3.tuple.Pair;
+import org.junit.jupiter.api.Test;
+
+public class JavaGroupingByCollectorUnitTest {
+
+    private static final List<BlogPost> posts = Arrays.asList(new BlogPost("News item 1", "Author 1", BlogPostType.NEWS, 15), new BlogPost("Tech review 1", "Author 2", BlogPostType.REVIEW, 5),
+        new BlogPost("Programming guide", "Author 1", BlogPostType.GUIDE, 20), new BlogPost("News item 2", "Author 2", BlogPostType.NEWS, 35), new BlogPost("Tech review 2", "Author 1", BlogPostType.REVIEW, 15));
+
+    @Test
+    public void givenAListOfPosts_whenGroupedByType_thenGetAMapBetweenTypeAndPosts() {
+        Map<BlogPostType, List<BlogPost>> postsPerType = posts.stream()
+            .collect(groupingBy(BlogPost::getType));
+
+        assertEquals(2, postsPerType.get(BlogPostType.NEWS)
+            .size());
+        assertEquals(1, postsPerType.get(BlogPostType.GUIDE)
+            .size());
+        assertEquals(2, postsPerType.get(BlogPostType.REVIEW)
+            .size());
+    }
+
+    @Test
+    public void givenAListOfPosts_whenGroupedByTypeAndTheirTitlesAreJoinedInAString_thenGetAMapBetweenTypeAndCsvTitles() {
+        Map<BlogPostType, String> postsPerType = posts.stream()
+            .collect(groupingBy(BlogPost::getType, mapping(BlogPost::getTitle, joining(", ", "Post titles: [", "]"))));
+
+        assertEquals("Post titles: [News item 1, News item 2]", postsPerType.get(BlogPostType.NEWS));
+        assertEquals("Post titles: [Programming guide]", postsPerType.get(BlogPostType.GUIDE));
+        assertEquals("Post titles: [Tech review 1, Tech review 2]", postsPerType.get(BlogPostType.REVIEW));
+    }
+
+    @Test
+    public void givenAListOfPosts_whenGroupedByTypeAndSumTheLikes_thenGetAMapBetweenTypeAndPostLikes() {
+        Map<BlogPostType, Integer> likesPerType = posts.stream()
+            .collect(groupingBy(BlogPost::getType, summingInt(BlogPost::getLikes)));
+
+        assertEquals(50, likesPerType.get(BlogPostType.NEWS)
+            .intValue());
+        assertEquals(20, likesPerType.get(BlogPostType.REVIEW)
+            .intValue());
+        assertEquals(20, likesPerType.get(BlogPostType.GUIDE)
+            .intValue());
+    }
+
+    @Test
+    public void givenAListOfPosts_whenGroupedByTypeInAnEnumMap_thenGetAnEnumMapBetweenTypeAndPosts() {
+        EnumMap<BlogPostType, List<BlogPost>> postsPerType = posts.stream()
+            .collect(groupingBy(BlogPost::getType, () -> new EnumMap<>(BlogPostType.class), toList()));
+
+        assertEquals(2, postsPerType.get(BlogPostType.NEWS)
+            .size());
+        assertEquals(1, postsPerType.get(BlogPostType.GUIDE)
+            .size());
+        assertEquals(2, postsPerType.get(BlogPostType.REVIEW)
+            .size());
+    }
+
+    @Test
+    public void givenAListOfPosts_whenGroupedByTypeInSets_thenGetAMapBetweenTypesAndSetsOfPosts() {
+        Map<BlogPostType, Set<BlogPost>> postsPerType = posts.stream()
+            .collect(groupingBy(BlogPost::getType, toSet()));
+
+        assertEquals(2, postsPerType.get(BlogPostType.NEWS)
+            .size());
+        assertEquals(1, postsPerType.get(BlogPostType.GUIDE)
+            .size());
+        assertEquals(2, postsPerType.get(BlogPostType.REVIEW)
+            .size());
+    }
+
+    @Test
+    public void givenAListOfPosts_whenGroupedByTypeConcurrently_thenGetAMapBetweenTypeAndPosts() {
+        ConcurrentMap<BlogPostType, List<BlogPost>> postsPerType = posts.parallelStream()
+            .collect(groupingByConcurrent(BlogPost::getType));
+
+        assertEquals(2, postsPerType.get(BlogPostType.NEWS)
+            .size());
+        assertEquals(1, postsPerType.get(BlogPostType.GUIDE)
+            .size());
+        assertEquals(2, postsPerType.get(BlogPostType.REVIEW)
+            .size());
+    }
+
+    @Test
+    public void givenAListOfPosts_whenGroupedByTypeAndAveragingLikes_thenGetAMapBetweenTypeAndAverageNumberOfLikes() {
+        Map<BlogPostType, Double> averageLikesPerType = posts.stream()
+            .collect(groupingBy(BlogPost::getType, averagingInt(BlogPost::getLikes)));
+
+        assertEquals(25, averageLikesPerType.get(BlogPostType.NEWS)
+            .intValue());
+        assertEquals(20, averageLikesPerType.get(BlogPostType.GUIDE)
+            .intValue());
+        assertEquals(10, averageLikesPerType.get(BlogPostType.REVIEW)
+            .intValue());
+    }
+
+    @Test
+    public void givenAListOfPosts_whenGroupedByTypeAndCounted_thenGetAMapBetweenTypeAndNumberOfPosts() {
+        Map<BlogPostType, Long> numberOfPostsPerType = posts.stream()
+            .collect(groupingBy(BlogPost::getType, counting()));
+
+        assertEquals(2, numberOfPostsPerType.get(BlogPostType.NEWS)
+            .intValue());
+        assertEquals(1, numberOfPostsPerType.get(BlogPostType.GUIDE)
+            .intValue());
+        assertEquals(2, numberOfPostsPerType.get(BlogPostType.REVIEW)
+            .intValue());
+    }
+
+    @Test
+    public void givenAListOfPosts_whenGroupedByTypeAndMaxingLikes_thenGetAMapBetweenTypeAndMaximumNumberOfLikes() {
+        Map<BlogPostType, Optional<BlogPost>> maxLikesPerPostType = posts.stream()
+            .collect(groupingBy(BlogPost::getType, maxBy(comparingInt(BlogPost::getLikes))));
+
+        assertTrue(maxLikesPerPostType.get(BlogPostType.NEWS)
+            .isPresent());
+        assertEquals(35, maxLikesPerPostType.get(BlogPostType.NEWS)
+            .get()
+            .getLikes());
+
+        assertTrue(maxLikesPerPostType.get(BlogPostType.GUIDE)
+            .isPresent());
+        assertEquals(20, maxLikesPerPostType.get(BlogPostType.GUIDE)
+            .get()
+            .getLikes());
+
+        assertTrue(maxLikesPerPostType.get(BlogPostType.REVIEW)
+            .isPresent());
+        assertEquals(15, maxLikesPerPostType.get(BlogPostType.REVIEW)
+            .get()
+            .getLikes());
+    }
+
+    @Test
+    public void givenAListOfPosts_whenGroupedByAuthorAndThenByType_thenGetAMapBetweenAuthorAndMapsBetweenTypeAndBlogPosts() {
+        Map<String, Map<BlogPostType, List<BlogPost>>> map = posts.stream()
+            .collect(groupingBy(BlogPost::getAuthor, groupingBy(BlogPost::getType)));
+
+        assertEquals(1, map.get("Author 1")
+            .get(BlogPostType.NEWS)
+            .size());
+        assertEquals(1, map.get("Author 1")
+            .get(BlogPostType.GUIDE)
+            .size());
+        assertEquals(1, map.get("Author 1")
+            .get(BlogPostType.REVIEW)
+            .size());
+
+        assertEquals(1, map.get("Author 2")
+            .get(BlogPostType.NEWS)
+            .size());
+        assertEquals(1, map.get("Author 2")
+            .get(BlogPostType.REVIEW)
+            .size());
+        assertNull(map.get("Author 2")
+            .get(BlogPostType.GUIDE));
+    }
+
+    @Test
+    public void givenAListOfPosts_whenGroupedByTypeAndSummarizingLikes_thenGetAMapBetweenTypeAndSummary() {
+        Map<BlogPostType, IntSummaryStatistics> likeStatisticsPerType = posts.stream()
+            .collect(groupingBy(BlogPost::getType, summarizingInt(BlogPost::getLikes)));
+
+        IntSummaryStatistics newsLikeStatistics = likeStatisticsPerType.get(BlogPostType.NEWS);
+
+        assertEquals(2, newsLikeStatistics.getCount());
+        assertEquals(50, newsLikeStatistics.getSum());
+        assertEquals(25.0, newsLikeStatistics.getAverage(), 0.001);
+        assertEquals(35, newsLikeStatistics.getMax());
+        assertEquals(15, newsLikeStatistics.getMin());
+    }
+
+    @Test
+    public void givenAListOfPosts_whenGroupedByComplexMapPairKeyType_thenGetAMapBetweenPairAndList() {
+
+        Map<Pair<BlogPostType, String>, List<BlogPost>> postsPerTypeAndAuthor = posts.stream()
+            .collect(groupingBy(post -> new ImmutablePair<>(post.getType(), post.getAuthor())));
+
+        List<BlogPost> result = postsPerTypeAndAuthor.get(new ImmutablePair<>(BlogPostType.GUIDE, "Author 1"));
+
+        assertThat(result.size()).isEqualTo(1);
+
+        BlogPost blogPost = result.get(0);
+
+        assertThat(blogPost.getTitle()).isEqualTo("Programming guide");
+        assertThat(blogPost.getType()).isEqualTo(BlogPostType.GUIDE);
+        assertThat(blogPost.getAuthor()).isEqualTo("Author 1");
+    }
+
+    @Test
+    public void givenAListOfPosts_whenGroupedByComplexMapKeyType_thenGetAMapBetweenTupleAndList() {
+
+        Map<Tuple, List<BlogPost>> postsPerTypeAndAuthor = posts.stream()
+            .collect(groupingBy(post -> new Tuple(post.getType(), post.getAuthor())));
+
+        List<BlogPost> result = postsPerTypeAndAuthor.get(new Tuple(BlogPostType.GUIDE, "Author 1"));
+
+        assertThat(result.size()).isEqualTo(1);
+
+        BlogPost blogPost = result.get(0);
+
+        assertThat(blogPost.getTitle()).isEqualTo("Programming guide");
+        assertThat(blogPost.getType()).isEqualTo(BlogPostType.GUIDE);
+        assertThat(blogPost.getAuthor()).isEqualTo("Author 1");
+    }
+
+    @Test
+    public void givenAListOfPosts_whenGroupedByRecord_thenGetAMapBetweenRecordAndList() {
+
+        Map<BlogPost.AuthPostTypesLikes, List<BlogPost>> postsPerTypeAndAuthor = posts.stream()
+            .collect(groupingBy(post -> new BlogPost.AuthPostTypesLikes(post.getAuthor(), post.getType(), post.getLikes())));
+
+        List<BlogPost> result = postsPerTypeAndAuthor.get(new BlogPost.AuthPostTypesLikes("Author 1", BlogPostType.GUIDE, 20));
+
+        assertThat(result.size()).isEqualTo(1);
+
+        BlogPost blogPost = result.get(0);
+
+        assertThat(blogPost.getTitle()).isEqualTo("Programming guide");
+        assertThat(blogPost.getType()).isEqualTo(BlogPostType.GUIDE);
+        assertThat(blogPost.getAuthor()).isEqualTo("Author 1");
+        assertThat(blogPost.getLikes()).isEqualTo(20);
+    }
+
+    @Test
+    public void givenListOfPosts_whenGroupedByAuthor_thenGetAMapUsingCollectingAndThen() {
+
+        Map<String, BlogPost.PostcountTitlesLikesStats> postsPerAuthor = posts.stream()
+            .collect(groupingBy(BlogPost::getAuthor, collectingAndThen(toList(), list -> {
+                long count = list.stream()
+                    .map(BlogPost::getTitle)
+                    .collect(counting());
+                String titles = list.stream()
+                    .map(BlogPost::getTitle)
+                    .collect(joining(" : "));
+                IntSummaryStatistics summary = list.stream()
+                    .collect(summarizingInt(BlogPost::getLikes));
+                return new BlogPost.PostcountTitlesLikesStats(count, titles, summary);
+            })));
+
+        BlogPost.PostcountTitlesLikesStats result = postsPerAuthor.get("Author 1");
+        assertThat(result.postCount()).isEqualTo(3L);
+        assertThat(result.titles()).isEqualTo("News item 1 : Programming guide : Tech review 2");
+        assertThat(result.likesStats().getMax()).isEqualTo(20);
+        assertThat(result.likesStats().getMin()).isEqualTo(15);
+        assertThat(result.likesStats().getAverage()).isEqualTo(16.666d, offset(0.001d));
+    }
+
+    @Test
+    public void givenListOfPosts_whenGroupedByAuthor_thenGetAMapUsingToMap() {
+
+        int maxValLikes = 17;
+        Map<String, BlogPost.TitlesBoundedSumOfLikes> postsPerAuthor = posts.stream()
+            .collect(toMap(BlogPost::getAuthor, post -> {
+                int likes = (post.getLikes() > maxValLikes) ? maxValLikes : post.getLikes();
+                return new BlogPost.TitlesBoundedSumOfLikes(post.getTitle(), likes);
+            }, (u1, u2) -> {
+                int likes = (u2.boundedSumOfLikes() > maxValLikes) ? maxValLikes : u2.boundedSumOfLikes();
+                return new BlogPost.TitlesBoundedSumOfLikes(u1.titles()
+                    .toUpperCase() + " : "
+                    + u2.titles()
+                        .toUpperCase(),
+                    u1.boundedSumOfLikes() + likes);
+            }));
+        
+        BlogPost.TitlesBoundedSumOfLikes result = postsPerAuthor.get("Author 1");
+        assertThat(result.titles()).isEqualTo("NEWS ITEM 1 : PROGRAMMING GUIDE : TECH REVIEW 2");
+        assertThat(result.boundedSumOfLikes()).isEqualTo(47);
+    }
+}

core-java-modules/core-java-concurrency-basic-2/src/main/java/com/baeldung/concurrent/stopexecution/StopExecution.java

@@ -189,21 +189,8 @@ public class StopExecution {
             longRunningSort();
         }
 
-        private void longRunningOperation() {
-            LOG.info("long Running operation started");
-
-            try {
-                //Thread.sleep(500);
-                longFileRead();
-                LOG.info("long running operation finished");
-            } catch (InterruptedException e) {
-                LOG.info("long Running operation interrupted");
-            }
-        }
-
         private void longRunningSort() {
-            LOG.info("long Running task started");
+            LOG.info("Long running task started");
-            // Do you long running calculation here
             int len = 100000;
             List<Integer> numbers = new ArrayList<>();
             try {
@@ -229,25 +216,7 @@ public class StopExecution {
                 LOG.info("Index position: " + i);
                 LOG.info("Long running task finished");
             } catch (InterruptedException e) {
-                LOG.info("long Running operation interrupted");
+                LOG.info("Long running operation interrupted");
-            }
-        }
-
-        private void longFileRead() throws InterruptedException {
-            String file = "input.txt";
-            ClassLoader classloader = getClass().getClassLoader();
-
-            try (InputStream inputStream = classloader.getResourceAsStream(file)) {
-                Reader inputStreamReader = new InputStreamReader(inputStream);
-
-                int data = inputStreamReader.read();
-                while (data != -1) {
-                    char theChar = (char) data;
-                    data = inputStreamReader.read();
-                    throwExceptionOnThreadInterrupt();
-                }
-            } catch (IOException e) {
-                LOG.error("Exception: ", e);
             }
         }
 

core-java-modules/core-java-date-operations-1/src/main/java/com/baeldung/java9/time/TimeApi.java

@@ -13,12 +13,9 @@ import java.util.stream.IntStream;
 public class TimeApi {
 
     public static List<Date> getDatesBetweenUsingJava7(Date startDate, Date endDate) {
-        List<Date> datesInRange = new ArrayList<Date>();
+        List<Date> datesInRange = new ArrayList<>();
-        Calendar calendar = new GregorianCalendar();
+        Calendar calendar = getCalendarWithoutTime(startDate);
-        calendar.setTime(startDate);
+        Calendar endCalendar = getCalendarWithoutTime(endDate);
-
-        Calendar endCalendar = new GregorianCalendar();
-        endCalendar.setTime(endDate);
 
         while (calendar.before(endCalendar)) {
             Date result = calendar.getTime();
@@ -40,4 +37,15 @@ public class TimeApi {
         return startDate.datesUntil(endDate).collect(Collectors.toList());
     }
 
+    private static Calendar getCalendarWithoutTime(Date date) {
+        Calendar calendar = new GregorianCalendar();
+        calendar.setTime(date);
+        calendar.set(Calendar.HOUR, 0);
+        calendar.set(Calendar.HOUR_OF_DAY, 0);
+        calendar.set(Calendar.MINUTE, 0);
+        calendar.set(Calendar.SECOND, 0);
+        calendar.set(Calendar.MILLISECOND, 0);
+        return calendar;
+    }
+
 }

core-java-modules/core-java-date-operations-1/src/test/java/com/baeldung/java9/time/TimeApiUnitTest.java

@@ -1,12 +1,13 @@
 package com.baeldung.java9.time;
 
+import org.junit.Test;
+
 import java.time.LocalDate;
 import java.util.Calendar;
 import java.util.Date;
 import java.util.List;
 
-import static org.junit.Assert.assertEquals;
+import static org.assertj.core.api.Assertions.assertThat;
-import org.junit.Test;
 
 public class TimeApiUnitTest {
 
@@ -18,19 +19,18 @@ public class TimeApiUnitTest {
         Date endDate = endCalendar.getTime();
 
         List<Date> dates = TimeApi.getDatesBetweenUsingJava7(startDate, endDate);
-        assertEquals(dates.size(), 2);
+
+        assertThat(dates).hasSize(2);
 
         Calendar calendar = Calendar.getInstance();
-        Date date1 = calendar.getTime();
+        Date expectedDate1 = calendar.getTime();
-        assertEquals(dates.get(0).getDay(), date1.getDay());
+        assertThat(dates.get(0)).isInSameDayAs(expectedDate1);
-        assertEquals(dates.get(0).getMonth(), date1.getMonth());
+        assertThatTimeFieldsAreZero(dates.get(0));
-        assertEquals(dates.get(0).getYear(), date1.getYear());
 
         calendar.add(Calendar.DATE, 1);
-        Date date2 = calendar.getTime();
+        Date expectedDate2 = calendar.getTime();
-        assertEquals(dates.get(1).getDay(), date2.getDay());
+        assertThat(dates.get(1)).isInSameDayAs(expectedDate2);
-        assertEquals(dates.get(1).getMonth(), date2.getMonth());
+        assertThatTimeFieldsAreZero(dates.get(1));
-        assertEquals(dates.get(1).getYear(), date2.getYear());
     }
 
     @Test
@@ -39,9 +39,8 @@ public class TimeApiUnitTest {
         LocalDate endDate = LocalDate.now().plusDays(2);
 
         List<LocalDate> dates = TimeApi.getDatesBetweenUsingJava8(startDate, endDate);
-        assertEquals(dates.size(), 2);
+
-        assertEquals(dates.get(0), LocalDate.now());
+        assertThat(dates).containsExactly(LocalDate.now(), LocalDate.now().plusDays(1));
-        assertEquals(dates.get(1), LocalDate.now().plusDays(1));
     }
 
     @Test
@@ -50,9 +49,15 @@ public class TimeApiUnitTest {
         LocalDate endDate = LocalDate.now().plusDays(2);
 
         List<LocalDate> dates = TimeApi.getDatesBetweenUsingJava9(startDate, endDate);
-        assertEquals(dates.size(), 2);
+
-        assertEquals(dates.get(0), LocalDate.now());
+        assertThat(dates).containsExactly(LocalDate.now(), LocalDate.now().plusDays(1));
-        assertEquals(dates.get(1), LocalDate.now().plusDays(1));
+    }
+
+    private static void assertThatTimeFieldsAreZero(Date date) {
+        assertThat(date).hasHourOfDay(0);
+        assertThat(date).hasMinute(0);
+        assertThat(date).hasSecond(0);
+        assertThat(date).hasMillisecond(0);
     }
 
 }

core-java-modules/core-java-datetime-string/pom.xml

@@ -75,7 +75,7 @@
 
     <properties>
         <commons-validator.version>1.6</commons-validator.version>
-        <joda-time.version>2.10</joda-time.version>
+        <joda-time.version>2.10.10</joda-time.version>
         <!-- testing -->
         <assertj.version>3.6.1</assertj.version>
         <maven.compiler.source>1.9</maven.compiler.source>

core-java-modules/core-java-datetime-string/src/test/java/com/baeldung/formatduration/FormatDurationUnitTest.java

@@ -0,0 +1,54 @@
+package com.baeldung.formatduration;
+
+import org.apache.commons.lang3.time.DurationFormatUtils;
+import org.joda.time.Period;
+import org.junit.Test;
+
+import java.time.Duration;
+import java.util.concurrent.TimeUnit;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class FormatDurationUnitTest {
+
+
+    @Test
+    public void givenInterval_WhenFormatInterval_formatDuration() {
+        long HH = TimeUnit.MILLISECONDS.toHours(38114000);
+        long MM = TimeUnit.MILLISECONDS.toMinutes(38114000) % 60;
+        long SS = TimeUnit.MILLISECONDS.toSeconds(38114000) % 60;
+        String timeInHHMMSS = String.format("%02d:%02d:%02d", HH, MM, SS);
+
+        assertThat(timeInHHMMSS).isEqualTo("10:35:14");
+    }
+
+    @Test
+    public void givenInterval_WhenFormatUsingDuration_formatDuration() {
+        Duration duration = Duration.ofMillis(38114000);
+        long seconds = duration.getSeconds();
+        long HH = seconds / 3600;
+        long MM = (seconds % 3600) / 60;
+        long SS = seconds % 60;
+        String timeInHHMMSS =  String.format("%02d:%02d:%02d", HH, MM, SS);
+        assertThat(timeInHHMMSS).isEqualTo("10:35:14");
+    }
+
+
+    @Test
+    public void givenInterval_WhenFormatDurationUsingApacheCommons_formatDuration() {
+        assertThat(DurationFormatUtils.formatDuration(38114000, "HH:mm:ss"))
+          .isEqualTo("10:35:14");
+    }
+
+    @Test
+    public void givenInterval_WhenFormatDurationUsingJodaTime_formatDuration() {
+        org.joda.time.Duration duration = new org.joda.time.Duration(38114000);
+        Period period = duration.toPeriod();
+        long HH = period.getHours();
+        long MM = period.getMinutes();
+        long SS = period.getSeconds();
+
+        String timeInHHMMSS = String.format("%02d:%02d:%02d", HH, MM, SS);
+        assertThat(timeInHHMMSS).isEqualTo("10:35:14");
+    }
+}

core-java-modules/core-java-lang-oop-constructors/README.md

@@ -7,3 +7,4 @@ This module contains article about constructors in Java
 - [Java Copy Constructor](https://www.baeldung.com/java-copy-constructor)
 - [Cannot Reference “X” Before Supertype Constructor Has Been Called](https://www.baeldung.com/java-cannot-reference-x-before-supertype-constructor-error)
 - [Private Constructors in Java](https://www.baeldung.com/java-private-constructors)
+- [Throwing Exceptions in Constructors](https://www.baeldung.com/java-constructors-exceptions)

core-java-modules/core-java-lang-oop-constructors/src/main/java/com/baeldung/constructors/exception/Animal.java

@@ -0,0 +1,32 @@
+package com.baeldung.constructors.exception;
+
+import java.io.File;
+import java.io.IOException;
+
+public class Animal {
+
+    public Animal() throws InstantiationException {
+        throw new InstantiationException("Cannot be instantiated");
+    }
+
+    public Animal(String id, int age) {
+        if (id == null)
+            throw new NullPointerException("Id cannot be null");
+        if (age < 0)
+            throw new IllegalArgumentException("Age cannot be negative");
+    }
+
+    public Animal(File file) throws SecurityException, IOException {
+        // Avoiding Path traversal attacks
+        if (file.isAbsolute()) {
+            throw new SecurityException("Traversal attack - absolute path not allowed");
+        }
+        // Avoiding directory traversal
+        // a/../..b/
+        if (!file.getCanonicalPath()
+            .equals(file.getAbsolutePath())) {
+            throw new SecurityException("Directory traversal attempt?");
+        }
+    }
+
+}

core-java-modules/core-java-lang-oop-constructors/src/main/java/com/baeldung/constructors/exception/Bird.java

@@ -0,0 +1,13 @@
+package com.baeldung.constructors.exception;
+
+public class Bird extends Animal {
+
+    // Note that we are throwing parent exception
+    public Bird() throws ReflectiveOperationException {
+        super();
+    }
+
+    public Bird(String id, int age) {
+        super(id, age);
+    }
+}

core-java-modules/core-java-lang-oop-constructors/src/test/java/com/baeldung/constructors/exception/AnimalUnitTest.java

@@ -0,0 +1,47 @@
+package com.baeldung.constructors.exception;
+
+import java.io.File;
+
+import org.assertj.core.api.Assertions;
+import org.junit.Test;
+
+public class AnimalUnitTest {
+
+    @Test
+    public void givenNoArgument_thenFails() {
+        Assertions.assertThatThrownBy(() -> {
+            new Animal();
+        })
+            .isInstanceOf(Exception.class);
+    }
+
+    @Test
+    public void givenInvalidArg_thenFails() {
+        Assertions.assertThatThrownBy(() -> {
+            new Animal(null, 30);
+        })
+            .isInstanceOf(NullPointerException.class);
+    }
+
+    @Test(expected = Test.None.class)
+    public void givenValidArg_thenSuccess() {
+        new Animal("1234", 30);
+    }
+
+    @Test
+    public void givenAbsolutePath_thenFails() {
+        Assertions.assertThatThrownBy(() -> {
+            new Animal(new File("temp.txt").getAbsoluteFile());
+        })
+            .isInstanceOf(SecurityException.class);
+    }
+
+    @Test
+    public void givenDirectoryTraversalPath_thenFails() {
+        Assertions.assertThatThrownBy(() -> {
+            new Animal(new File(File.separator + ".." + File.separator + "temp.txt"));
+        })
+            .isInstanceOf(SecurityException.class);
+    }
+
+}

core-java-modules/core-java-lang-operators-2/README.md

@@ -5,3 +5,4 @@ This module contains articles about Java operators
 ## Relevant Articles:
 
 - [Logical vs Bitwise OR Operator](https://www.baeldung.com/java-logical-vs-bitwise-or-operator)
+- [Bitmasking in Java with Bitwise Operators](https://www.baeldung.com/java-bitmasking)

core-java-modules/core-java-os/src/test/java/com/baeldung/grep/GrepWithUnix4JIntegrationTest.java

@@ -25,9 +25,9 @@ public class GrepWithUnix4JIntegrationTest {
 
     @Test
     public void whenGrepWithSimpleString_thenCorrect() {
-        int expectedLineCount = 4;
+        int expectedLineCount = 5;
 
-        // grep "NINETEEN" dictionary.txt
+        // grep "NINETEEN" dictionary.in
         List<Line> lines = Unix4j.grep("NINETEEN", fileToGrep).toLineList();
 
         assertEquals(expectedLineCount, lines.size());
@@ -35,9 +35,9 @@ public class GrepWithUnix4JIntegrationTest {
 
     @Test
     public void whenInverseGrepWithSimpleString_thenCorrect() {
-        int expectedLineCount = 178687;
+        int expectedLineCount = 8;
 
-        // grep -v "NINETEEN" dictionary.txt
+        // grep -v "NINETEEN" dictionary.in
         List<Line> lines = grep(Options.v, "NINETEEN", fileToGrep).toLineList();
 
         assertEquals(expectedLineCount, lines.size());
@@ -45,9 +45,9 @@ public class GrepWithUnix4JIntegrationTest {
 
     @Test
     public void whenGrepWithRegex_thenCorrect() {
-        int expectedLineCount = 151;
+        int expectedLineCount = 5;
 
-        // grep -c ".*?NINE.*?" dictionary.txt
+        // grep -c ".*?NINE.*?" dictionary.in
         String patternCount = grep(Options.c, ".*?NINE.*?", fileToGrep).cut(fields, ":", 1).toStringResult();
 
         assertEquals(expectedLineCount, Integer.parseInt(patternCount));

core-java-modules/core-java-os/src/test/resources/dictionary.in

@@ -0,0 +1,13 @@
+EIGHTTEEN
+EIGHTTEENS
+EIGHTTEENTH
+EIGHTTEENTHS
+NINETEEN
+NINETEENS
+NINETEENTH
+NINETEENTHS
+TWENTY
+TWENTHIES
+TWENTHIETH
+TWENTHIETHS
+TWENTYNINETEEN

core-java-modules/core-java-string-operations-3/README.md

@@ -4,3 +4,4 @@
 - [Java (String) or .toString()?](https://www.baeldung.com/java-string-casting-vs-tostring)
 - [Split Java String by Newline](https://www.baeldung.com/java-string-split-by-newline)
 - [Split a String in Java and Keep the Delimiters](https://www.baeldung.com/java-split-string-keep-delimiters)
+- [Validate String as Filename in Java](https://www.baeldung.com/java-validate-filename)

core-java-modules/core-java-string-operations-3/src/main/java/com/baeldung/stringfilenamevalidaiton/StringFilenameValidationUtils.java

@@ -0,0 +1,61 @@
+package com.baeldung.stringfilenamevalidaiton;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Paths;
+import java.util.Arrays;
+
+public class StringFilenameValidationUtils {
+
+    public static final Character[] INVALID_WINDOWS_SPECIFIC_CHARS = {'"', '*', ':', '<', '>', '?', '\\', '|', 0x7F};
+    public static final Character[] INVALID_UNIX_SPECIFIC_CHARS = {'\000'};
+
+    public static final String REGEX_PATTERN = "^[A-za-z0-9.]{1,255}$";
+
+    private StringFilenameValidationUtils() {
+    }
+
+    public static boolean validateStringFilenameUsingIO(String filename) throws IOException {
+        File file = new File(filename);
+        boolean created = false;
+        try {
+            created = file.createNewFile();
+            return created;
+        } finally {
+            if (created) {
+                file.delete();
+            }
+        }
+    }
+
+    public static boolean validateStringFilenameUsingNIO2(String filename) {
+        Paths.get(filename);
+        return true;
+    }
+
+    public static boolean validateStringFilenameUsingContains(String filename) {
+        if (filename == null || filename.isEmpty() || filename.length() > 255) {
+            return false;
+        }
+        return Arrays.stream(getInvalidCharsByOS())
+            .noneMatch(ch -> filename.contains(ch.toString()));
+    }
+
+    public static boolean validateStringFilenameUsingRegex(String filename) {
+        if (filename == null) {
+            return false;
+        }
+        return filename.matches(REGEX_PATTERN);
+    }
+
+    private static Character[] getInvalidCharsByOS() {
+        String os = System.getProperty("os.name").toLowerCase();
+        if (os.contains("win")) {
+            return INVALID_WINDOWS_SPECIFIC_CHARS;
+        } else if (os.contains("nix") || os.contains("nux") || os.contains("mac")) {
+            return INVALID_UNIX_SPECIFIC_CHARS;
+        } else {
+            return new Character[]{};
+        }
+    }
+}

core-java-modules/core-java-string-operations-3/src/test/java/com/baeldung/stringfilenamevalidaiton/StringFilenameValidationUnitTest.java

@@ -0,0 +1,130 @@
+package com.baeldung.stringfilenamevalidaiton;
+
+import org.apache.commons.lang3.RandomStringUtils;
+import org.apache.commons.lang3.RandomUtils;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.condition.EnabledOnOs;
+import org.junit.jupiter.api.condition.OS;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.EmptySource;
+import org.junit.jupiter.params.provider.MethodSource;
+import org.junit.jupiter.params.provider.NullSource;
+
+import java.io.IOException;
+import java.nio.file.InvalidPathException;
+import java.util.Arrays;
+import java.util.stream.Stream;
+
+import static com.baeldung.stringfilenamevalidaiton.StringFilenameValidationUtils.validateStringFilenameUsingContains;
+import static com.baeldung.stringfilenamevalidaiton.StringFilenameValidationUtils.validateStringFilenameUsingIO;
+import static com.baeldung.stringfilenamevalidaiton.StringFilenameValidationUtils.validateStringFilenameUsingNIO2;
+import static com.baeldung.stringfilenamevalidaiton.StringFilenameValidationUtils.validateStringFilenameUsingRegex;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+public class StringFilenameValidationUnitTest {
+
+    private static final String CORRECT_FILENAME_PATTERN = "baeldung.txt";
+
+    @ParameterizedTest
+    @MethodSource("correctAlphanumericFilenamesProvider")
+    public void givenCorrectAlphanumericRandomFilenameString_whenValidateUsingIO_thenReturnTrue(String filename) throws IOException {
+        assertThat(validateStringFilenameUsingIO(filename)).isTrue();
+        assertThat(validateStringFilenameUsingNIO2(filename)).isTrue();
+        assertThat(validateStringFilenameUsingContains(filename)).isTrue();
+        assertThat(validateStringFilenameUsingRegex(filename)).isTrue();
+    }
+
+    @Test
+    public void givenTooLongFileNameString_whenValidate_thenIOAndCustomFailsNIO2Succeed() {
+        String filename = RandomStringUtils.randomAlphabetic(500);
+        assertThatThrownBy(() -> validateStringFilenameUsingIO(filename))
+            .isInstanceOf(IOException.class)
+            .hasMessageContaining("File name too long");
+        assertThat(validateStringFilenameUsingNIO2(filename)).isTrue();
+        assertThat(validateStringFilenameUsingContains(filename)).isFalse();
+        assertThat(validateStringFilenameUsingRegex(filename)).isFalse();
+    }
+
+    @ParameterizedTest
+    @NullSource
+    public void givenNullString_whenValidate_thenFails(String filename) {
+        assertThatThrownBy(() -> validateStringFilenameUsingIO(filename))
+            .isInstanceOf(NullPointerException.class);
+        assertThatThrownBy(() -> validateStringFilenameUsingNIO2(filename))
+            .isInstanceOf(NullPointerException.class);
+        assertThat(validateStringFilenameUsingContains(filename)).isFalse();
+        assertThat(validateStringFilenameUsingRegex(filename)).isFalse();
+    }
+
+    @ParameterizedTest
+    @EmptySource
+    public void givenEmptyString_whenValidate_thenIOAndCustomFailsNIO2Succeed(String filename) {
+        assertThatThrownBy(() -> validateStringFilenameUsingIO(filename))
+            .isInstanceOf(IOException.class);
+        assertThat(validateStringFilenameUsingNIO2(filename)).isTrue();
+        assertThat(validateStringFilenameUsingContains(filename)).isFalse();
+        assertThat(validateStringFilenameUsingRegex(filename)).isFalse();
+    }
+
+    @ParameterizedTest
+    @EnabledOnOs({OS.LINUX, OS.MAC})
+    @MethodSource("filenamesWithInvalidWindowsChars")
+    public void givenFilenameStringWithInvalidWindowsCharAndIsUnix_whenValidateUsingIO_thenReturnTrue(String filename) throws IOException {
+        assertThat(validateStringFilenameUsingIO(filename)).isTrue();
+        assertThat(validateStringFilenameUsingNIO2(filename)).isTrue();
+        assertThat(validateStringFilenameUsingContains(filename)).isTrue();
+    }
+
+    @ParameterizedTest
+    @EnabledOnOs(OS.WINDOWS)
+    @MethodSource("filenamesWithInvalidWindowsChars")
+    public void givenFilenameStringWithInvalidWindowsCharAndIsWindows_whenValidateUsingIO_thenRaiseException(String filename) {
+        assertThatThrownBy(() -> validateStringFilenameUsingIO(filename))
+            .isInstanceOf(IOException.class)
+            .hasMessageContaining("Invalid file path");
+
+        assertThatThrownBy(() -> validateStringFilenameUsingNIO2(filename))
+            .isInstanceOf(InvalidPathException.class)
+            .hasMessage("character not allowed");
+
+        assertThat(validateStringFilenameUsingContains(filename)).isFalse();
+    }
+
+    @ParameterizedTest
+    @EnabledOnOs({OS.LINUX, OS.MAC})
+    @MethodSource("filenamesWithInvalidUnixChars")
+    public void givenFilenameStringWithInvalidUnixCharAndIsUnix_whenValidate_thenRaiseException(String filename) {
+        assertThatThrownBy(() -> validateStringFilenameUsingIO(filename))
+            .isInstanceOf(IOException.class)
+            .hasMessageContaining("Invalid file path");
+
+        assertThatThrownBy(() -> validateStringFilenameUsingNIO2(filename))
+            .isInstanceOf(InvalidPathException.class)
+            .hasMessageContaining("character not allowed");
+
+        assertThat(validateStringFilenameUsingContains(filename)).isFalse();
+    }
+
+
+    private static Stream<String> correctAlphanumericFilenamesProvider() {
+        return Stream.generate(() -> RandomStringUtils.randomAlphanumeric(1, 10) + "." + RandomStringUtils.randomAlphabetic(3, 5)).limit(10);
+    }
+
+    private static Stream<String> filenamesWithInvalidWindowsChars() {
+        return Arrays.stream(StringFilenameValidationUtils.INVALID_WINDOWS_SPECIFIC_CHARS)
+            .map(character -> {
+                int idx = RandomUtils.nextInt(0, CORRECT_FILENAME_PATTERN.length());
+                return CORRECT_FILENAME_PATTERN.substring(0, idx) + character + CORRECT_FILENAME_PATTERN.substring(idx);
+            });
+    }
+
+    private static Stream<String> filenamesWithInvalidUnixChars() {
+        return Arrays.stream(StringFilenameValidationUtils.INVALID_UNIX_SPECIFIC_CHARS)
+            .map(character -> {
+                int idx = RandomUtils.nextInt(0, CORRECT_FILENAME_PATTERN.length());
+                return CORRECT_FILENAME_PATTERN.substring(0, idx) + character + CORRECT_FILENAME_PATTERN.substring(idx);
+            });
+    }
+
+}

docker/heap-sizing/pom.xml

@@ -1,21 +1,21 @@
 <?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"
+<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>
-    <parent>
-        <groupId>org.springframework.boot</groupId>
-        <artifactId>spring-boot-starter-parent</artifactId>
-        <version>2.4.2</version>
-        <relativePath/> <!-- lookup parent from repository -->
-    </parent>
     <groupId>com.baeldung.docker</groupId>
     <artifactId>heap-sizing</artifactId>
     <version>0.0.1-SNAPSHOT</version>
     <name>heap-sizing</name>
     <description>Demo project for Spring Boot</description>
-    <properties>
+
-        <java.version>11</java.version>
+    <parent>
-    </properties>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-boot-2</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../parent-boot-2</relativePath>
+    </parent>
+
     <dependencies>
         <dependency>
             <groupId>org.springframework.boot</groupId>
@@ -58,4 +58,8 @@
         </plugins>
     </build>
 
+    <properties>
+        <java.version>11</java.version>
+    </properties>
+
 </project>

drools/src/main/resources/logback.xml

@@ -6,7 +6,8 @@
             </pattern>
         </encoder>
     </appender>
-
+	<logger name="org.kie.api.internal.utils" level="WARN"/>
+	<logger name="org.drools.compiler" level="WARN"/>
     <root level="INFO">
         <appender-ref ref="STDOUT" />
     </root>

gradle/gradle-dependency-management/build.gradle

@@ -3,6 +3,11 @@ plugins {
     id 'org.springframework.boot' version '2.3.4.RELEASE'
 }
 
+ext {
+    springBootVersion = '2.3.4.RELEASE'
+    lombokVersion = '1.18.14'
+}
+
 group = 'com.gradle'
 version = '1.0.0'
 sourceCompatibility = '14'
@@ -12,19 +17,16 @@ repositories {
 }
 
 dependencies {
-    implementation 'org.springframework.boot:spring-boot-starter:2.3.4.RELEASE'
+    implementation "org.springframework.boot:spring-boot-starter:${springBootVersion}"
 
-    testImplementation 'org.springframework.boot:spring-boot-starter-test:2.3.4.RELEASE'
+    compileOnly "org.projectlombok:lombok:${lombokVersion}"
-
-    compileOnly 'org.projectlombok:lombok:1.18.14'
-
-    testCompileOnly 'org.projectlombok:lombok:1.18.14'
 
     runtimeOnly files('libs/sampleOne.jar', 'libs/sampleTwo.jar')
+    runtimeOnly fileTree("libs") { include "*.jar" }
 
-    runtimeOnly fileTree('libs') { include '*.jar' }
+    testImplementation "org.springframework.boot:spring-boot-starter-test:${springBootVersion}"
 
-//    implementation gradleApi()
+    testCompileOnly "org.projectlombok:lombok:${lombokVersion}"
 }
 
 test {

gradle/gradle-dependency-management/gradlew

@@ -0,0 +1,234 @@
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
+done
+
+APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
+
+APP_NAME="Gradle"
+APP_BASE_NAME=${0##*/}
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&2
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD=$JAVA_HOME/jre/sh/java
+    else
+        JAVACMD=$JAVA_HOME/bin/java
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+# Collect all arguments for the java command;
+#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
+#     shell script including quotes and variable substitutions, so put them in
+#     double quotes to make sure that they get re-expanded; and
+#   * put everything else in single quotes, so that it's not re-expanded.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
+exec "$JAVACMD" "$@"

gradle/gradle-dependency-management/gradlew.bat

@@ -0,0 +1,89 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

javafx/README.md

@@ -4,4 +4,5 @@ This module contains articles about JavaFX.
 
 ### Relevant Articles:
 - [Introduction to JavaFX](https://www.baeldung.com/javafx)
+- [Display Custom Items in JavaFX ListView](https://www.baeldung.com/javafx-listview-display-custom-items)
 

javafx/src/main/java/com/baeldung/listview/ExampleController.java

@@ -0,0 +1,38 @@
+package com.baeldung.listview;
+
+import com.baeldung.listview.cellfactory.CheckboxCellFactory;
+import com.baeldung.listview.cellfactory.PersonCellFactory;
+import javafx.collections.FXCollections;
+import javafx.collections.ObservableList;
+import javafx.fxml.FXML;
+import javafx.fxml.Initializable;
+import javafx.scene.control.ListView;
+
+import java.net.URL;
+import java.util.ResourceBundle;
+
+public class ExampleController implements Initializable {
+    @FXML
+    private ListView<Person> listView;
+
+    @Override
+    public void initialize(URL location, ResourceBundle resources) {
+        ObservableList<Person> wordsList = FXCollections.observableArrayList();
+        wordsList.add(new Person("Isaac", "Newton"));
+        wordsList.add(new Person("Albert", "Einstein"));
+        wordsList.add(new Person("Ludwig", "Boltzmann"));
+        listView.setItems(wordsList);
+    }
+
+    public void defaultButtonClick() {
+        listView.setCellFactory(null);
+    }
+
+    public void cellFactoryButtonClick() {
+        listView.setCellFactory(new PersonCellFactory());
+    }
+
+    public void checkboxCellFactoryButtonClick() {
+        listView.setCellFactory(new CheckboxCellFactory());
+    }
+}

javafx/src/main/java/com/baeldung/listview/Main.java

@@ -0,0 +1,28 @@
+package com.baeldung.javafx.listview;
+
+import javafx.application.Application;
+import javafx.fxml.FXMLLoader;
+import javafx.scene.Parent;
+import javafx.scene.Scene;
+import javafx.stage.Stage;
+
+import java.net.URL;
+
+public class Main extends Application {
+
+    public static void main(String args[]) {
+        launch(args);
+    }
+
+    @Override
+    public void start(Stage primaryStage) throws Exception {
+        FXMLLoader loader = new FXMLLoader();
+        URL xmlUrl = getClass().getResource("/example.fxml");
+        loader.setLocation(xmlUrl);
+        Parent root = loader.load();
+
+        primaryStage.setTitle("List View Demo");
+        primaryStage.setScene(new Scene(root));
+        primaryStage.show();
+    }
+}

javafx/src/main/java/com/baeldung/listview/Person.java

@@ -0,0 +1,25 @@
+package com.baeldung.listview;
+
+public class Person {
+
+    private final String firstName;
+    private final String lastName;
+
+    public Person(String firstName, String lastName) {
+        this.firstName = firstName;
+        this.lastName = lastName;
+    }
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    @Override
+    public String toString() {
+        return firstName + " " + lastName;
+    }
+}

javafx/src/main/java/com/baeldung/listview/cellfactory/CheckboxCellFactory.java

@@ -0,0 +1,29 @@
+package com.baeldung.listview.cellfactory;
+
+import com.baeldung.listview.Person;
+import javafx.scene.control.CheckBox;
+import javafx.scene.control.ListCell;
+import javafx.scene.control.ListView;
+import javafx.util.Callback;
+
+public class CheckboxCellFactory implements Callback<ListView<Person>, ListCell<Person>> {
+    @Override
+    public ListCell<Person> call(ListView<Person> param) {
+        return new ListCell<Person>(){
+            @Override
+            public void updateItem(Person person, boolean empty) {
+                super.updateItem(person, empty);
+                if (empty) {
+                    setText(null);
+                    setGraphic(null);
+                } else if (person != null) {
+                    setText(null);
+                    setGraphic(new CheckBox(person.getFirstName() + " " + person.getLastName()));
+                } else {
+                    setText("null");
+                    setGraphic(null);
+                }
+            }
+        };
+    }
+}

javafx/src/main/java/com/baeldung/listview/cellfactory/PersonCellFactory.java

@@ -0,0 +1,23 @@
+package com.baeldung.listview.cellfactory;
+
+import com.baeldung.listview.Person;
+import javafx.scene.control.ListCell;
+import javafx.scene.control.ListView;
+import javafx.util.Callback;
+
+public class PersonCellFactory implements Callback<ListView<Person>, ListCell<Person>> {
+    @Override
+    public ListCell<Person> call(ListView<Person> param) {
+        return new ListCell<Person>(){
+            @Override
+            public void updateItem(Person person, boolean empty) {
+                super.updateItem(person, empty);
+                if (empty || person == null) {
+                    setText(null);
+                } else {
+                    setText(person.getFirstName() + " " + person.getLastName());
+                }
+            }
+        };
+    }
+}

javafx/src/main/resources/example.fxml

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<?import javafx.scene.control.Button?>
+<?import javafx.scene.control.ListView?>
+<?import javafx.scene.layout.AnchorPane?>
+
+<AnchorPane prefHeight="188.0" prefWidth="457.0" xmlns="http://javafx.com/javafx/8.0.172-ea" xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.baeldung.listview.ExampleController">
+   <children>
+      <ListView id="listView" fx:id="listView" layoutX="14.0" layoutY="25.0" prefHeight="138.0" prefWidth="256.0" />
+      <Button layoutX="283.0" layoutY="25.0" mnemonicParsing="false" onAction="#defaultButtonClick" prefHeight="25.0" prefWidth="139.0" text="Default" />
+      <Button layoutX="283.0" layoutY="63.0" mnemonicParsing="false" onAction="#cellFactoryButtonClick" prefHeight="25.0" prefWidth="139.0" text="Cell Factory" />
+      <Button layoutX="283.0" layoutY="104.0" mnemonicParsing="false" onAction="#checkboxCellFactoryButtonClick" prefHeight="25.0" prefWidth="139.0" text="Checkbox Cell Factory" />
+   </children>
+</AnchorPane>

jersey/src/main/java/com/baeldung/jersey/server/config/HelloDynamicBinding.java

@@ -5,20 +5,14 @@ import javax.ws.rs.container.ResourceInfo;
 import javax.ws.rs.core.FeatureContext;
 import javax.ws.rs.ext.Provider;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 import com.baeldung.jersey.server.Greetings;
 import com.baeldung.jersey.server.filter.ResponseServerFilter;
 
 @Provider
 public class HelloDynamicBinding implements DynamicFeature {
 
-    private static final Logger LOG = LoggerFactory.getLogger(HelloDynamicBinding.class);
-
     @Override
     public void configure(ResourceInfo resourceInfo, FeatureContext context) {
-        LOG.info("Hello dynamic binding");
 
         if (Greetings.class.equals(resourceInfo.getResourceClass()) && resourceInfo.getResourceMethod()
             .getName()

jhipster/jhipster-microservice/car-app/pom.xml

@@ -17,7 +17,6 @@
     </prerequisites>
 
     <properties>
-        <lifecycle.mapping.version>1.0.0</lifecycle.mapping.version>
         <argLine>-Djava.security.egd=file:/dev/./urandom -Xmx256m</argLine>
         <assertj.version>3.6.2</assertj.version>
         <awaitility.version>2.0.0</awaitility.version>
@@ -31,6 +30,7 @@
         <jcache.version>1.0.0</jcache.version>
         <jhipster.server.version>1.1.0</jhipster.server.version>
         <jjwt.version>0.7.0</jjwt.version>
+        <lifecycle.mapping.version>1.0.0</lifecycle.mapping.version>
         <liquibase-hibernate5.version>3.6</liquibase-hibernate5.version>
         <liquibase-slf4j.version>2.0.0</liquibase-slf4j.version>
         <liquibase.version>3.6.2</liquibase.version>
@@ -349,7 +349,6 @@
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-test</artifactId>
-            <scope>test</scope>
         </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
@@ -365,11 +364,6 @@
                 </exclusion>
             </exclusions>
         </dependency>
-        <dependency>
-            <groupId>org.springframework.boot</groupId>
-            <artifactId>spring-boot-test</artifactId>
-            <scope>test</scope>
-        </dependency>
         <!-- Spring Cloud -->
         <dependency>
             <groupId>org.springframework.cloud</groupId>
@@ -580,14 +574,6 @@
                     </execution>
                 </executions>
             </plugin>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-surefire-plugin</artifactId>
-                <configuration>
-                    <!-- Force alphabetical order to have a reproducible build -->
-                    <runOrder>alphabetical</runOrder>
-                </configuration>
-            </plugin>
             <plugin>
                 <groupId>org.jacoco</groupId>
                 <artifactId>jacoco-maven-plugin</artifactId>

jhipster/jhipster-microservice/car-app/src/test/resources/config/application.yml

@@ -21,6 +21,8 @@ eureka:
         instanceId: carapp:${spring.application.instance_id:${random.value}}
 
 spring:
+    main:
+        banner-mode: "off"
     application:
         name: carapp
     jackson:
@@ -37,7 +39,7 @@ spring:
         database-platform: io.github.jhipster.domain.util.FixedH2Dialect
         database: H2
         open-in-view: false
-        show-sql: true
+        show-sql: false
         hibernate:
             ddl-auto: none
             naming:

jhipster/jhipster-microservice/car-app/src/test/resources/logback-test.xml

@@ -3,7 +3,7 @@
 <configuration scan="true">
     <include resource="org/springframework/boot/logging/logback/base.xml"/>
 
-    <logger name="com.car.app" level="DEBUG"/>
+    <logger name="com.car.app" level="INFO"/>
     <logger name="org.hibernate" level="WARN"/>
     <logger name="org.hibernate.ejb.HibernatePersistence" level="OFF"/>
     <logger name="org.apache.catalina.startup.DigesterFactory" level="OFF"/>

jhipster/jhipster-microservice/dealer-app/pom.xml

@@ -29,6 +29,7 @@
         <jcache.version>1.0.0</jcache.version>
         <jhipster.server.version>1.1.0</jhipster.server.version>
         <jjwt.version>0.7.0</jjwt.version>
+        <lifecycle.mapping.version>1.0.0</lifecycle.mapping.version>
         <liquibase-hibernate5.version>3.6</liquibase-hibernate5.version>
         <liquibase-slf4j.version>2.0.0</liquibase-slf4j.version>
         <liquibase.version>3.6.2</liquibase.version>
@@ -90,7 +91,6 @@
         <undertow.version>1.4.10.Final</undertow.version>
         <validation-api.version>1.1.0.Final</validation-api.version>
         <yarn.version>v0.21.3</yarn.version>
-        <lifecycle.mapping.version>1.0.0</lifecycle.mapping.version>
     </properties>
 
     <dependencyManagement>
@@ -345,6 +345,10 @@
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-security</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+        </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-thymeleaf</artifactId>
@@ -359,11 +363,6 @@
                 </exclusion>
             </exclusions>
         </dependency>
-        <dependency>
-            <groupId>org.springframework.boot</groupId>
-            <artifactId>spring-boot-test</artifactId>
-            <scope>test</scope>
-        </dependency>
         <!-- Spring Cloud -->
         <dependency>
             <groupId>org.springframework.cloud</groupId>
@@ -574,14 +573,6 @@
                     </execution>
                 </executions>
             </plugin>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-surefire-plugin</artifactId>
-                <configuration>
-                    <!-- Force alphabetical order to have a reproducible build -->
-                    <runOrder>alphabetical</runOrder>
-                </configuration>
-            </plugin>
             <plugin>
                 <groupId>org.jacoco</groupId>
                 <artifactId>jacoco-maven-plugin</artifactId>

jhipster/jhipster-microservice/dealer-app/src/test/resources/config/application.yml

@@ -21,6 +21,8 @@ eureka:
         instanceId: dealerapp:${spring.application.instance_id:${random.value}}
 
 spring:
+    main:
+        banner-mode: "off"
     application:
         name: dealerapp
     jackson:
@@ -37,7 +39,7 @@ spring:
         database-platform: io.github.jhipster.domain.util.FixedH2Dialect
         database: H2
         open-in-view: false
-        show-sql: true
+        show-sql: false
         hibernate:
             ddl-auto: none
             naming:

jhipster/jhipster-microservice/dealer-app/src/test/resources/logback-test.xml

@@ -3,7 +3,7 @@
 <configuration scan="true">
     <include resource="org/springframework/boot/logging/logback/base.xml"/>
 
-    <logger name="com.dealer.app" level="DEBUG"/>
+    <logger name="com.dealer.app" level="INFO"/>
     <logger name="org.hibernate" level="WARN"/>
     <logger name="org.hibernate.ejb.HibernatePersistence" level="OFF"/>
     <logger name="org.apache.catalina.startup.DigesterFactory" level="OFF"/>

jhipster/jhipster-microservice/gateway-app/pom.xml

@@ -32,6 +32,7 @@
         <jcache.version>1.0.0</jcache.version>
         <jhipster.server.version>1.1.0</jhipster.server.version>
         <jjwt.version>0.7.0</jjwt.version>
+        <lifecycle.mapping.version>1.0.0</lifecycle.mapping.version>
         <liquibase-hibernate5.version>3.6</liquibase-hibernate5.version>
         <liquibase-slf4j.version>2.0.0</liquibase-slf4j.version>
         <liquibase.version>3.6.2</liquibase.version>
@@ -94,7 +95,6 @@
         <undertow.version>1.4.10.Final</undertow.version>
         <validation-api.version>1.1.0.Final</validation-api.version>
         <yarn.version>v0.21.3</yarn.version>
-        <lifecycle.mapping.version>1.0.0</lifecycle.mapping.version>
     </properties>
 
     <dependencyManagement>
@@ -383,6 +383,10 @@
             <artifactId>spring-boot-starter-test</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+        </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-thymeleaf</artifactId>
@@ -397,11 +401,6 @@
                 </exclusion>
             </exclusions>
         </dependency>
-        <dependency>
-            <groupId>org.springframework.boot</groupId>
-            <artifactId>spring-boot-test</artifactId>
-            <scope>test</scope>
-        </dependency>
         <dependency>
             <groupId>org.springframework.cloud</groupId>
             <artifactId>spring-cloud-starter</artifactId>
@@ -632,14 +631,6 @@
                     </execution>
                 </executions>
             </plugin>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-surefire-plugin</artifactId>
-                <configuration>
-                    <!-- Force alphabetical order to have a reproducible build -->
-                    <runOrder>alphabetical</runOrder>
-                </configuration>
-            </plugin>
             <plugin>
                 <groupId>org.jacoco</groupId>
                 <artifactId>jacoco-maven-plugin</artifactId>

jhipster/jhipster-microservice/gateway-app/src/test/java/com/gateway/web/rest/LogsResourceIntegrationTest.java

@@ -49,7 +49,7 @@ public class LogsResourceIntegrationTest {
     public void changeLogs()throws Exception {
         LoggerVM logger = new LoggerVM();
         logger.setLevel("INFO");
-        logger.setName("ROOT");
+        logger.setName("some.test.logger");
 
         restLogsMockMvc.perform(put("/management/logs")
             .contentType(TestUtil.APPLICATION_JSON_UTF8)

jhipster/jhipster-microservice/gateway-app/src/test/resources/config/application.yml

@@ -21,6 +21,8 @@ eureka:
         instanceId: gateway:${spring.application.instance_id:${random.value}}
 
 spring:
+    main:
+        banner-mode: "off"
     application:
         name: gateway
     autoconfigure:
@@ -39,7 +41,7 @@ spring:
         database-platform: io.github.jhipster.domain.util.FixedH2Dialect
         database: H2
         open-in-view: false
-        show-sql: true
+        show-sql: false
         hibernate:
             ddl-auto: none
             naming:

jhipster/jhipster-microservice/gateway-app/src/test/resources/logback-test.xml

@@ -3,7 +3,7 @@
 <configuration scan="true">
     <include resource="org/springframework/boot/logging/logback/base.xml"/>
 
-    <logger name="com.gateway" level="DEBUG"/>
+    <logger name="com.gateway" level="INFO"/>
     <logger name="org.hibernate" level="WARN"/>
     <logger name="org.hibernate.ejb.HibernatePersistence" level="OFF"/>
     <logger name="org.apache.catalina.startup.DigesterFactory" level="OFF"/>

jhipster/jhipster-monolithic/pom.xml

@@ -277,8 +277,7 @@
         </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
-            <artifactId>spring-boot-test</artifactId>
+            <artifactId>spring-boot-starter-test</artifactId>
-            <scope>test</scope>
         </dependency>
         <!-- security -->
         <dependency>

jhipster/jhipster-monolithic/src/test/java/com/baeldung/web/rest/LogsResourceIntegrationTest.java

@@ -49,7 +49,7 @@ public class LogsResourceIntegrationTest {
     public void changeLogs()throws Exception {
         LoggerVM logger = new LoggerVM();
         logger.setLevel("INFO");
-        logger.setName("ROOT");
+        logger.setName("some.test.logger");
 
         restLogsMockMvc.perform(put("/management/logs")
             .contentType(TestUtil.APPLICATION_JSON_UTF8)

jhipster/jhipster-monolithic/src/test/resources/config/application.yml

@@ -15,6 +15,8 @@
 
 
 spring:
+    main:
+        banner-mode: "off"
     application:
         name: baeldung
     jackson:
@@ -31,7 +33,7 @@ spring:
         database-platform: io.github.jhipster.domain.util.FixedH2Dialect
         database: H2
         open-in-view: false
-        show-sql: true
+        show-sql: false
         hibernate:
             ddl-auto: none
             naming:

jhipster/jhipster-monolithic/src/test/resources/logback-test.xml

@@ -3,7 +3,7 @@
 <configuration scan="true">
     <include resource="org/springframework/boot/logging/logback/base.xml"/>
 
-    <logger name="com.baeldung" level="DEBUG"/>
+    <logger name="com.baeldung" level="INFO"/>
     <logger name="org.hibernate" level="WARN"/>
     <logger name="org.hibernate.ejb.HibernatePersistence" level="OFF"/>
     <logger name="org.apache.catalina.startup.DigesterFactory" level="OFF"/>

jhipster/jhipster-uaa/gateway/pom.xml

@@ -1,6 +1,13 @@
 <?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/maven-v4_0_0.xsd">
     <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <artifactId>jhipster-uaa</artifactId>
+        <groupId>com.baeldung.jhipster</groupId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
     <groupId>com.baeldung.jhipster.gateway</groupId>
     <artifactId>gateway</artifactId>
     <version>0.0.1-SNAPSHOT</version>
@@ -415,15 +422,6 @@
                     </execution>
                 </executions>
             </plugin>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-surefire-plugin</artifactId>
-                <version>${maven-surefire-plugin.version}</version>
-                <configuration>
-                    <!-- Force alphabetical order to have a reproducible build -->
-                    <runOrder>alphabetical</runOrder>
-                </configuration>
-            </plugin>
             <plugin>
                 <groupId>org.jacoco</groupId>
                 <artifactId>jacoco-maven-plugin</artifactId>

jhipster/jhipster-uaa/gateway/src/test/java/com/baeldung/jhipster/gateway/config/WebConfigurerUnitTest.java

@@ -40,7 +40,7 @@ import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.
  *
  * @see WebConfigurer
  */
-public class WebConfigurerTest {
+public class WebConfigurerUnitTest {
 
     private WebConfigurer webConfigurer;
 

jhipster/jhipster-uaa/gateway/src/test/java/com/baeldung/jhipster/gateway/gateway/responserewriting/SwaggerBasePathRewritingFilterUnitTest.java

@@ -18,7 +18,7 @@ import static springfox.documentation.swagger2.web.Swagger2Controller.DEFAULT_UR
 /**
  * Tests SwaggerBasePathRewritingFilter class.
  */
-public class SwaggerBasePathRewritingFilterTest {
+public class SwaggerBasePathRewritingFilterUnitTest {
 
     private SwaggerBasePathRewritingFilter filter = new SwaggerBasePathRewritingFilter();
 

jhipster/jhipster-uaa/gateway/src/test/java/com/baeldung/jhipster/gateway/security/oauth2/CookieCollectionUnitTest.java

@@ -16,7 +16,7 @@ import java.util.List;
  *
  * @see CookieCollection
  */
-public class CookieCollectionTest {
+public class CookieCollectionUnitTest {
     public static final String COOKIE_NAME = "chocolate";
     public static final String COOKIE_VALUE = "yummy";
     public static final String BROWNIE_NAME = "brownie";

jhipster/jhipster-uaa/gateway/src/test/java/com/baeldung/jhipster/gateway/security/oauth2/CookieTokenExtractorUnitTest.java

@@ -12,7 +12,7 @@ import org.springframework.security.oauth2.common.OAuth2AccessToken;
  * Test whether the CookieTokenExtractor can properly extract access tokens from
  * Cookies and Headers.
  */
-public class CookieTokenExtractorTest {
+public class CookieTokenExtractorUnitTest {
     private CookieTokenExtractor cookieTokenExtractor;
 
     @Before
@@ -22,24 +22,24 @@ public class CookieTokenExtractorTest {
 
     @Test
     public void testExtractTokenCookie() {
-        MockHttpServletRequest request = OAuth2AuthenticationServiceTest.createMockHttpServletRequest();
+        MockHttpServletRequest request = OAuth2AuthenticationServiceUnitTest.createMockHttpServletRequest();
         Authentication authentication = cookieTokenExtractor.extract(request);
-        Assert.assertEquals(OAuth2AuthenticationServiceTest.ACCESS_TOKEN_VALUE, authentication.getPrincipal().toString());
+        Assert.assertEquals(OAuth2AuthenticationServiceUnitTest.ACCESS_TOKEN_VALUE, authentication.getPrincipal().toString());
     }
 
     @Test
     public void testExtractTokenHeader() {
         MockHttpServletRequest request = new MockHttpServletRequest(HttpMethod.GET.name(), "http://www.test.com");
-        request.addHeader("Authorization", OAuth2AccessToken.BEARER_TYPE + " " + OAuth2AuthenticationServiceTest.ACCESS_TOKEN_VALUE);
+        request.addHeader("Authorization", OAuth2AccessToken.BEARER_TYPE + " " + OAuth2AuthenticationServiceUnitTest.ACCESS_TOKEN_VALUE);
         Authentication authentication = cookieTokenExtractor.extract(request);
-        Assert.assertEquals(OAuth2AuthenticationServiceTest.ACCESS_TOKEN_VALUE, authentication.getPrincipal().toString());
+        Assert.assertEquals(OAuth2AuthenticationServiceUnitTest.ACCESS_TOKEN_VALUE, authentication.getPrincipal().toString());
     }
 
     @Test
     public void testExtractTokenParam() {
         MockHttpServletRequest request = new MockHttpServletRequest(HttpMethod.GET.name(), "http://www.test.com");
-        request.addParameter(OAuth2AccessToken.ACCESS_TOKEN, OAuth2AuthenticationServiceTest.ACCESS_TOKEN_VALUE);
+        request.addParameter(OAuth2AccessToken.ACCESS_TOKEN, OAuth2AuthenticationServiceUnitTest.ACCESS_TOKEN_VALUE);
         Authentication authentication = cookieTokenExtractor.extract(request);
-        Assert.assertEquals(OAuth2AuthenticationServiceTest.ACCESS_TOKEN_VALUE, authentication.getPrincipal().toString());
+        Assert.assertEquals(OAuth2AuthenticationServiceUnitTest.ACCESS_TOKEN_VALUE, authentication.getPrincipal().toString());
     }
 }

jhipster/jhipster-uaa/gateway/src/test/java/com/baeldung/jhipster/gateway/security/oauth2/OAuth2AuthenticationServiceUnitTest.java

@@ -39,7 +39,7 @@ import static org.mockito.Mockito.when;
  * @see OAuth2AuthenticationService
  */
 @RunWith(MockitoJUnitRunner.class)
-public class OAuth2AuthenticationServiceTest {
+public class OAuth2AuthenticationServiceUnitTest {
     public static final String CLIENT_AUTHORIZATION = "Basic d2ViX2FwcDpjaGFuZ2VpdA==";
     public static final String ACCESS_TOKEN_VALUE = "eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJleHAiOjE0OTQyNzI4NDQsInVzZXJfbmFtZSI6InVzZXIiLCJhdXRob3JpdGllcyI6WyJST0xFX1VTRVIiXSwianRpIjoiNzc1ZTJkYWUtYWYzZi00YTdhLWExOTktNzNiZTU1MmIxZDVkIiwiY2xpZW50X2lkIjoid2ViX2FwcCIsInNjb3BlIjpbIm9wZW5pZCJdfQ.gEK0YcX2IpkpxnkxXXHQ4I0xzTjcy7edqb89ukYE0LPe7xUcZVwkkCJF_nBxsGJh2jtA6NzNLfY5zuL6nP7uoAq3fmvsyrcyR2qPk8JuuNzGtSkICx3kPDRjAT4ST8SZdeh7XCbPVbySJ7ZmPlRWHyedzLA1wXN0NUf8yZYS4ELdUwVBYIXSjkNoKqfWm88cwuNr0g0teypjPtjDqCnXFt1pibwdfIXn479Y1neNAdvSpHcI4Ost-c7APCNxW2gqX-0BItZQearxRgKDdBQ7CGPAIky7dA0gPuKUpp_VCoqowKCXqkE9yKtRQGIISewtj2UkDRZePmzmYrUBXRzfYw";
     public static final String REFRESH_TOKEN_VALUE = "eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VyX25hbWUiOiJ1c2VyIiwic2NvcGUiOlsib3BlbmlkIl0sImF0aSI6Ijc3NWUyZGFlLWFmM2YtNGE3YS1hMTk5LTczYmU1NTJiMWQ1ZCIsImV4cCI6MTQ5Njg2NDc0MywiYXV0aG9yaXRpZXMiOlsiUk9MRV9VU0VSIl0sImp0aSI6IjhmYjI2YTllLTdjYzQtNDFlMi1hNzBjLTk4MDc0N2U2YWFiOSIsImNsaWVudF9pZCI6IndlYl9hcHAifQ.q1-Df9_AFO6TJNiLKV2YwTjRbnd7qcXv52skXYnog5siHYRoR6cPtm6TNQ04iDAoIHljTSTNnD6DS3bHk41mV55gsSVxGReL8VCb_R8ZmhVL4-5yr90sfms0wFp6lgD2bPmZ-TXiS2Oe9wcbNWagy5RsEplZ-sbXu3tjmDao4FN35ojPsXmUs84XnNQH3Y_-PY9GjZG0JEfLQIvE0J5BkXS18Z015GKyA6GBIoLhAGBQQYyG9m10ld_a9fD5SmCyCF72Jad_pfP1u8Z_WyvO-wrlBvm2x-zBthreVrXU5mOb9795wJEP-xaw3dXYGjht_grcW4vKUFtj61JgZk98CQ";

jhipster/jhipster-uaa/gateway/src/test/java/com/baeldung/jhipster/gateway/security/oauth2/OAuth2CookieHelperUnitTest.java

@@ -12,7 +12,7 @@ import org.springframework.test.util.ReflectionTestUtils;
  *
  * @see OAuth2CookieHelper
  */
-public class OAuth2CookieHelperTest {
+public class OAuth2CookieHelperUnitTest {
     public static final String GET_COOKIE_DOMAIN_METHOD = "getCookieDomain";
     private OAuth2Properties oAuth2Properties;
     private OAuth2CookieHelper cookieHelper;