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Merge pull request #5 from eugenp/master

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Krzysztof Majewski 2019-09-03 16:12:03 +02:00 committed by GitHub
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24
.travis.yml
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@ -1,24 +0,0 @@
language: java
before_install:
- echo "MAVEN_OPTS='-Xmx2048M -Xss128M -XX:+CMSClassUnloadingEnabled -XX:+UseG1GC -XX:-UseGCOverheadLimit'" > ~/.mavenrc
install: skip
script: travis_wait 60 mvn -q install -Pdefault-first,default-second -Dgib.enabled=true
sudo: required
jdk:
- oraclejdk8
addons:
apt:
packages:
- oracle-java8-installer
cache:
directories:
- .autoconf
- $HOME/.m2

1
algorithms-miscellaneous-3/README.md
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@ -7,3 +7,4 @@
- [Checking If a List Is Sorted in Java](https://www.baeldung.com/java-check-if-list-sorted)
- [Checking if a Java Graph has a Cycle](https://www.baeldung.com/java-graph-has-a-cycle)
- [A Guide to the Folding Technique in Java](https://www.baeldung.com/folding-hashing-technique)
- [Creating a Triangle with for Loops in Java](https://www.baeldung.com/java-print-triangle)

30
algorithms-miscellaneous-3/pom.xml
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@ -1,5 +1,5 @@
<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">
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>algorithms-miscellaneous-3</artifactId>
<version>0.0.1-SNAPSHOT</version>
@ -18,17 +18,28 @@
<version>${org.assertj.core.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-collections4</artifactId>
<version>${commons-collections4.version}</version>
<groupId>org.apache.commons</groupId>
<artifactId>commons-collections4</artifactId>
<version>${commons-collections4.version}</version>
</dependency>
<dependency>
<groupId>com.google.guava</groupId>
<artifactId>guava</artifactId>
<version>${guava.version}</version>
<groupId>com.google.guava</groupId>
<artifactId>guava</artifactId>
<version>${guava.version}</version>
</dependency>
<dependency>
<groupId>com.squareup.retrofit2</groupId>
<artifactId>retrofit</artifactId>
<version>${retrofit.version}</version>
</dependency>
<dependency>
<groupId>com.squareup.retrofit2</groupId>
<artifactId>converter-jackson</artifactId>
<version>${retrofit.version}</version>
</dependency>
<dependency>
@ -61,5 +72,6 @@
<org.assertj.core.version>3.9.0</org.assertj.core.version>
<commons-collections4.version>4.3</commons-collections4.version>
<guava.version>28.0-jre</guava.version>
<retrofit.version>2.6.0</retrofit.version>
</properties>
</project>

35
algorithms-miscellaneous-3/src/main/java/com/baeldung/algorithms/interpolationsearch/InterpolationSearch.java Normal file
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package com.baeldung.algorithms.interpolationsearch;
public class InterpolationSearch {
public static int interpolationSearch(int[] data, int item) {
int highEnd = (data.length - 1);
int lowEnd = 0;
while (item >= data[lowEnd] && item <= data[highEnd] && lowEnd <= highEnd) {
int probe = lowEnd + (highEnd - lowEnd) * (item - data[lowEnd]) / (data[highEnd] - data[lowEnd]);
if (highEnd == lowEnd) {
if (data[lowEnd] == item) {
return lowEnd;
} else {
return -1;
}
}
if (data[probe] == item) {
return probe;
}
if (data[probe] < item) {
lowEnd = probe + 1;
} else {
highEnd = probe - 1;
}
}
return -1;
}
}

45
algorithms-miscellaneous-3/src/main/java/com/baeldung/algorithms/kmeans/Centroid.java Normal file
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package com.baeldung.algorithms.kmeans;
import java.util.Map;
import java.util.Objects;
/**
* Encapsulates all coordinates for a particular cluster centroid.
*/
public class Centroid {
/**
* The centroid coordinates.
*/
private final Map<String, Double> coordinates;
public Centroid(Map<String, Double> coordinates) {
this.coordinates = coordinates;
}
public Map<String, Double> getCoordinates() {
return coordinates;
}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
Centroid centroid = (Centroid) o;
return Objects.equals(getCoordinates(), centroid.getCoordinates());
}
@Override
public int hashCode() {
return Objects.hash(getCoordinates());
}
@Override
public String toString() {
return "Centroid " + coordinates;
}
}

20
algorithms-miscellaneous-3/src/main/java/com/baeldung/algorithms/kmeans/Distance.java Normal file
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package com.baeldung.algorithms.kmeans;
import java.util.Map;
/**
* Defines a contract to calculate distance between two feature vectors. The less the
* calculated distance, the more two items are similar to each other.
*/
public interface Distance {
/**
* Calculates the distance between two feature vectors.
*
* @param f1 The first set of features.
* @param f2 The second set of features.
* @return Calculated distance.
* @throws IllegalArgumentException If the given feature vectors are invalid.
*/
double calculate(Map<String, Double> f1, Map<String, Double> f2);
}

23
algorithms-miscellaneous-3/src/main/java/com/baeldung/algorithms/kmeans/Errors.java Normal file
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package com.baeldung.algorithms.kmeans;
import java.util.List;
import java.util.Map;
/**
* Encapsulates methods to calculates errors between centroid and the cluster members.
*/
public class Errors {
public static double sse(Map<Centroid, List<Record>> clustered, Distance distance) {
double sum = 0;
for (Map.Entry<Centroid, List<Record>> entry : clustered.entrySet()) {
Centroid centroid = entry.getKey();
for (Record record : entry.getValue()) {
double d = distance.calculate(centroid.getCoordinates(), record.getFeatures());
sum += Math.pow(d, 2);
}
}
return sum;
}
}

26
algorithms-miscellaneous-3/src/main/java/com/baeldung/algorithms/kmeans/EuclideanDistance.java Normal file
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@ -0,0 +1,26 @@
package com.baeldung.algorithms.kmeans;
import java.util.Map;
/**
* Calculates the distance between two items using the Euclidean formula.
*/
public class EuclideanDistance implements Distance {
@Override
public double calculate(Map<String, Double> f1, Map<String, Double> f2) {
if (f1 == null || f2 == null) {
throw new IllegalArgumentException("Feature vectors can't be null");
}
double sum = 0;
for (String key : f1.keySet()) {
Double v1 = f1.get(key);
Double v2 = f2.get(key);
if (v1 != null && v2 != null) sum += Math.pow(v1 - v2, 2);
}
return Math.sqrt(sum);
}
}

236
algorithms-miscellaneous-3/src/main/java/com/baeldung/algorithms/kmeans/KMeans.java Normal file
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package com.baeldung.algorithms.kmeans;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Random;
import java.util.Set;
import static java.util.stream.Collectors.toList;
import static java.util.stream.Collectors.toSet;
/**
* Encapsulates an implementation of KMeans clustering algorithm.
*
* @author Ali Dehghani
*/
public class KMeans {
private KMeans() {
throw new IllegalAccessError("You shouldn't call this constructor");
}
/**
* Will be used to generate random numbers.
*/
private static final Random random = new Random();
/**
* Performs the K-Means clustering algorithm on the given dataset.
*
* @param records The dataset.
* @param k Number of Clusters.
* @param distance To calculate the distance between two items.
* @param maxIterations Upper bound for the number of iterations.
* @return K clusters along with their features.
*/
public static Map<Centroid, List<Record>> fit(List<Record> records, int k, Distance distance, int maxIterations) {
applyPreconditions(records, k, distance, maxIterations);
List<Centroid> centroids = randomCentroids(records, k);
Map<Centroid, List<Record>> clusters = new HashMap<>();
Map<Centroid, List<Record>> lastState = new HashMap<>();
// iterate for a pre-defined number of times
for (int i = 0; i < maxIterations; i++) {
boolean isLastIteration = i == maxIterations - 1;
// in each iteration we should find the nearest centroid for each record
for (Record record : records) {
Centroid centroid = nearestCentroid(record, centroids, distance);
assignToCluster(clusters, record, centroid);
}
// if the assignment does not change, then the algorithm terminates
boolean shouldTerminate = isLastIteration || clusters.equals(lastState);
lastState = clusters;
if (shouldTerminate) {
break;
}
// at the end of each iteration we should relocate the centroids
centroids = relocateCentroids(clusters);
clusters = new HashMap<>();
}
return lastState;
}
/**
* Move all cluster centroids to the average of all assigned features.
*
* @param clusters The current cluster configuration.
* @return Collection of new and relocated centroids.
*/
private static List<Centroid> relocateCentroids(Map<Centroid, List<Record>> clusters) {
return clusters
.entrySet()
.stream()
.map(e -> average(e.getKey(), e.getValue()))
.collect(toList());
}
/**
* Moves the given centroid to the average position of all assigned features. If
* the centroid has no feature in its cluster, then there would be no need for a
* relocation. Otherwise, for each entry we calculate the average of all records
* first by summing all the entries and then dividing the final summation value by
* the number of records.
*
* @param centroid The centroid to move.
* @param records The assigned features.
* @return The moved centroid.
*/
private static Centroid average(Centroid centroid, List<Record> records) {
// if this cluster is empty, then we shouldn't move the centroid
if (records == null || records.isEmpty()) {
return centroid;
}
// Since some records don't have all possible attributes, we initialize
// average coordinates equal to current centroid coordinates
Map<String, Double> average = centroid.getCoordinates();
// The average function works correctly if we clear all coordinates corresponding
// to present record attributes
records
.stream()
.flatMap(e -> e
.getFeatures()
.keySet()
.stream())
.forEach(k -> average.put(k, 0.0));
for (Record record : records) {
record
.getFeatures()
.forEach((k, v) -> average.compute(k, (k1, currentValue) -> v + currentValue));
}
average.forEach((k, v) -> average.put(k, v / records.size()));
return new Centroid(average);
}
/**
* Assigns a feature vector to the given centroid. If this is the first assignment for this centroid,
* first we should create the list.
*
* @param clusters The current cluster configuration.
* @param record The feature vector.
* @param centroid The centroid.
*/
private static void assignToCluster(Map<Centroid, List<Record>> clusters, Record record, Centroid centroid) {
clusters.compute(centroid, (key, list) -> {
if (list == null) {
list = new ArrayList<>();
}
list.add(record);
return list;
});
}
/**
* With the help of the given distance calculator, iterates through centroids and finds the
* nearest one to the given record.
*
* @param record The feature vector to find a centroid for.
* @param centroids Collection of all centroids.
* @param distance To calculate the distance between two items.
* @return The nearest centroid to the given feature vector.
*/
private static Centroid nearestCentroid(Record record, List<Centroid> centroids, Distance distance) {
double minimumDistance = Double.MAX_VALUE;
Centroid nearest = null;
for (Centroid centroid : centroids) {
double currentDistance = distance.calculate(record.getFeatures(), centroid.getCoordinates());
if (currentDistance < minimumDistance) {
minimumDistance = currentDistance;
nearest = centroid;
}
}
return nearest;
}
/**
* Generates k random centroids. Before kicking-off the centroid generation process,
* first we calculate the possible value range for each attribute. Then when
* we're going to generate the centroids, we generate random coordinates in
* the [min, max] range for each attribute.
*
* @param records The dataset which helps to calculate the [min, max] range for
* each attribute.
* @param k Number of clusters.
* @return Collections of randomly generated centroids.
*/
private static List<Centroid> randomCentroids(List<Record> records, int k) {
List<Centroid> centroids = new ArrayList<>();
Map<String, Double> maxs = new HashMap<>();
Map<String, Double> mins = new HashMap<>();
for (Record record : records) {
record
.getFeatures()
.forEach((key, value) -> {
// compares the value with the current max and choose the bigger value between them
maxs.compute(key, (k1, max) -> max == null || value > max ? value : max);
// compare the value with the current min and choose the smaller value between them
mins.compute(key, (k1, min) -> min == null || value < min ? value : min);
});
}
Set<String> attributes = records
.stream()
.flatMap(e -> e
.getFeatures()
.keySet()
.stream())
.collect(toSet());
for (int i = 0; i < k; i++) {
Map<String, Double> coordinates = new HashMap<>();
for (String attribute : attributes) {
double max = maxs.get(attribute);
double min = mins.get(attribute);
coordinates.put(attribute, random.nextDouble() * (max - min) + min);
}
centroids.add(new Centroid(coordinates));
}
return centroids;
}
private static void applyPreconditions(List<Record> records, int k, Distance distance, int maxIterations) {
if (records == null || records.isEmpty()) {
throw new IllegalArgumentException("The dataset can't be empty");
}
if (k <= 1) {
throw new IllegalArgumentException("It doesn't make sense to have less than or equal to 1 cluster");
}
if (distance == null) {
throw new IllegalArgumentException("The distance calculator is required");
}
if (maxIterations <= 0) {
throw new IllegalArgumentException("Max iterations should be a positive number");
}
}
}

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algorithms-miscellaneous-3/src/main/java/com/baeldung/algorithms/kmeans/LastFm.java Normal file
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package com.baeldung.algorithms.kmeans;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.stream.Collectors;
import com.fasterxml.jackson.databind.ObjectMapper;
import okhttp3.OkHttpClient;
import retrofit2.Retrofit;
import retrofit2.converter.jackson.JacksonConverterFactory;
import static java.util.stream.Collectors.toSet;
public class LastFm {
private static OkHttpClient okHttp = new OkHttpClient.Builder()
.addInterceptor(new LastFmService.Authenticator("put your API key here"))
.build();
private static Retrofit retrofit = new Retrofit.Builder()
.client(okHttp)
.addConverterFactory(JacksonConverterFactory.create())
.baseUrl("http://ws.audioscrobbler.com/")
.build();
private static LastFmService lastFm = retrofit.create(LastFmService.class);
private static ObjectMapper mapper = new ObjectMapper();
public static void main(String[] args) throws IOException {
List<String> artists = getTop100Artists();
Set<String> tags = getTop100Tags();
List<Record> records = datasetWithTaggedArtists(artists, tags);
Map<Centroid, List<Record>> clusters = KMeans.fit(records, 7, new EuclideanDistance(), 1000);
// Print the cluster configuration
clusters.forEach((key, value) -> {
System.out.println("------------------------------ CLUSTER -----------------------------------");
System.out.println(sortedCentroid(key));
String members = String.join(", ", value
.stream()
.map(Record::getDescription)
.collect(toSet()));
System.out.print(members);
System.out.println();
System.out.println();
});
Map<String, Object> json = convertToD3CompatibleMap(clusters);
System.out.println(mapper.writeValueAsString(json));
}
private static Map<String, Object> convertToD3CompatibleMap(Map<Centroid, List<Record>> clusters) {
Map<String, Object> json = new HashMap<>();
json.put("name", "Musicians");
List<Map<String, Object>> children = new ArrayList<>();
clusters.forEach((key, value) -> {
Map<String, Object> child = new HashMap<>();
child.put("name", dominantGenre(sortedCentroid(key)));
List<Map<String, String>> nested = new ArrayList<>();
for (Record record : value) {
nested.add(Collections.singletonMap("name", record.getDescription()));
}
child.put("children", nested);
children.add(child);
});
json.put("children", children);
return json;
}
private static String dominantGenre(Centroid centroid) {
return centroid
.getCoordinates()
.keySet()
.stream()
.limit(2)
.collect(Collectors.joining(", "));
}
private static Centroid sortedCentroid(Centroid key) {
List<Map.Entry<String, Double>> entries = new ArrayList<>(key
.getCoordinates()
.entrySet());
entries.sort((e1, e2) -> e2
.getValue()
.compareTo(e1.getValue()));
Map<String, Double> sorted = new LinkedHashMap<>();
for (Map.Entry<String, Double> entry : entries) {
sorted.put(entry.getKey(), entry.getValue());
}
return new Centroid(sorted);
}
private static List<Record> datasetWithTaggedArtists(List<String> artists, Set<String> topTags) throws IOException {
List<Record> records = new ArrayList<>();
for (String artist : artists) {
Map<String, Double> tags = lastFm
.topTagsFor(artist)
.execute()
.body()
.all();
// Only keep popular tags.
tags
.entrySet()
.removeIf(e -> !topTags.contains(e.getKey()));
records.add(new Record(artist, tags));
}
return records;
}
private static Set<String> getTop100Tags() throws IOException {
return lastFm
.topTags()
.execute()
.body()
.all();
}
private static List<String> getTop100Artists() throws IOException {
List<String> artists = new ArrayList<>();
for (int i = 1; i <= 2; i++) {
artists.addAll(lastFm
.topArtists(i)
.execute()
.body()
.all());
}
return artists;
}
}

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algorithms-miscellaneous-3/src/main/java/com/baeldung/algorithms/kmeans/LastFmService.java Normal file
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package com.baeldung.algorithms.kmeans;
import java.io.IOException;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.stream.Collectors;
import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.JsonProperty;
import okhttp3.HttpUrl;
import okhttp3.Interceptor;
import okhttp3.Request;
import okhttp3.Response;
import retrofit2.Call;
import retrofit2.http.GET;
import retrofit2.http.Query;
import static com.fasterxml.jackson.annotation.JsonAutoDetect.Visibility.ANY;
import static java.util.stream.Collectors.toList;
public interface LastFmService {
@GET("/2.0/?method=chart.gettopartists&format=json&limit=50")
Call<Artists> topArtists(@Query("page") int page);
@GET("/2.0/?method=artist.gettoptags&format=json&limit=20&autocorrect=1")
Call<Tags> topTagsFor(@Query("artist") String artist);
@GET("/2.0/?method=chart.gettoptags&format=json&limit=100")
Call<TopTags> topTags();
/**
* HTTP interceptor to intercept all HTTP requests and add the API key to them.
*/
class Authenticator implements Interceptor {
private final String apiKey;
Authenticator(String apiKey) {
this.apiKey = apiKey;
}
@Override
public Response intercept(Chain chain) throws IOException {
HttpUrl url = chain
.request()
.url()
.newBuilder()
.addQueryParameter("api_key", apiKey)
.build();
Request request = chain
.request()
.newBuilder()
.url(url)
.build();
return chain.proceed(request);
}
}
@JsonAutoDetect(fieldVisibility = ANY)
class TopTags {
private Map<String, Object> tags;
@SuppressWarnings("unchecked")
public Set<String> all() {
List<Map<String, Object>> topTags = (List<Map<String, Object>>) tags.get("tag");
return topTags
.stream()
.map(e -> ((String) e.get("name")))
.collect(Collectors.toSet());
}
}
@JsonAutoDetect(fieldVisibility = ANY)
class Tags {
@JsonProperty("toptags") private Map<String, Object> topTags;
@SuppressWarnings("unchecked")
public Map<String, Double> all() {
try {
Map<String, Double> all = new HashMap<>();
List<Map<String, Object>> tags = (List<Map<String, Object>>) topTags.get("tag");
for (Map<String, Object> tag : tags) {
all.put(((String) tag.get("name")), ((Integer) tag.get("count")).doubleValue());
}
return all;
} catch (Exception e) {
return Collections.emptyMap();
}
}
}
@JsonAutoDetect(fieldVisibility = ANY)
class Artists {
private Map<String, Object> artists;
@SuppressWarnings("unchecked")
public List<String> all() {
try {
List<Map<String, Object>> artists = (List<Map<String, Object>>) this.artists.get("artist");
return artists
.stream()
.map(e -> ((String) e.get("name")))
.collect(toList());
} catch (Exception e) {
return Collections.emptyList();
}
}
}
}

65
algorithms-miscellaneous-3/src/main/java/com/baeldung/algorithms/kmeans/Record.java Normal file
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@ -0,0 +1,65 @@
package com.baeldung.algorithms.kmeans;
import java.util.Map;
import java.util.Objects;
/**
* Encapsulates all feature values for a few attributes. Optionally each record
* can be described with the {@link #description} field.
*/
public class Record {
/**
* The record description. For example, this can be the artist name for the famous musician
* example.
*/
private final String description;
/**
* Encapsulates all attributes and their corresponding values, i.e. features.
*/
private final Map<String, Double> features;
public Record(String description, Map<String, Double> features) {
this.description = description;
this.features = features;
}
public Record(Map<String, Double> features) {
this("", features);
}
public String getDescription() {
return description;
}
public Map<String, Double> getFeatures() {
return features;
}
@Override
public String toString() {
String prefix = description == null || description
.trim()
.isEmpty() ? "Record" : description;
return prefix + ": " + features;
}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
Record record = (Record) o;
return Objects.equals(getDescription(), record.getDescription()) && Objects.equals(getFeatures(), record.getFeatures());
}
@Override
public int hashCode() {
return Objects.hash(getDescription(), getFeatures());
}
}

16
algorithms-miscellaneous-3/src/main/java/com/baeldung/algorithms/printtriangles/PrintTriangleExamples.java
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@ -4,7 +4,7 @@ import org.apache.commons.lang3.StringUtils;
public class PrintTriangleExamples {
public static String printARightAngledTriangle(int N) {
public static String printARightTriangle(int N) {
StringBuilder result = new StringBuilder();
for (int r = 1; r <= N; r++) {
for (int j = 1; j <= r; j++) {
@ -29,6 +29,17 @@ public class PrintTriangleExamples {
return result.toString();
}
public static String printAnIsoscelesTriangleUsingStringUtils(int N) {
StringBuilder result = new StringBuilder();
for (int r = 1; r <= N; r++) {
result.append(StringUtils.repeat(' ', N - r));
result.append(StringUtils.repeat('*', 2 * r - 1));
result.append(System.lineSeparator());
}
return result.toString();
}
public static String printAnIsoscelesTriangleUsingSubstring(int N) {
StringBuilder result = new StringBuilder();
String helperString = StringUtils.repeat(' ', N - 1) + StringUtils.repeat('*', N * 2 - 1);
@ -41,8 +52,9 @@ public class PrintTriangleExamples {
}
public static void main(String[] args) {
System.out.println(printARightAngledTriangle(5));
System.out.println(printARightTriangle(5));
System.out.println(printAnIsoscelesTriangle(5));
System.out.println(printAnIsoscelesTriangleUsingStringUtils(5));
System.out.println(printAnIsoscelesTriangleUsingSubstring(5));
}

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algorithms-miscellaneous-3/src/main/resources/kmeans/artists.json Normal file
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algorithms-miscellaneous-3/src/main/resources/kmeans/lastfm.json Normal file
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@ -0,0 +1,490 @@
{
"children": [
{
"children": [
{
"name": "Radiohead"
},
{
"name": "Red Hot Chili Peppers"
},
{
"name": "Coldplay"
},
{
"name": "Nirvana"
},
{
"name": "Panic! at the Disco"
},
{
"name": "The Cure"
},
{
"name": "Linkin Park"
},
{
"name": "Radiohead"
},
{
"name": "Red Hot Chili Peppers"
},
{
"name": "Coldplay"
},
{
"name": "Nirvana"
},
{
"name": "Panic! at the Disco"
},
{
"name": "The Cure"
},
{
"name": "Linkin Park"
},
{
"name": "Muse"
},
{
"name": "Maroon 5"
},
{
"name": "Foo Fighters"
},
{
"name": "Paramore"
},
{
"name": "Oasis"
},
{
"name": "Fall Out Boy"
},
{
"name": "OneRepublic"
},
{
"name": "Weezer"
},
{
"name": "System of a Down"
},
{
"name": "The White Stripes"
}
],
"name": "rock, alternative"
},
{
"children": [
{
"name": "Lil Nas X"
},
{
"name": "Post Malone"
},
{
"name": "Drake"
},
{
"name": "Kanye West"
},
{
"name": "Kendrick Lamar"
},
{
"name": "Tyler, the Creator"
},
{
"name": "Eminem"
},
{
"name": "Childish Gambino"
},
{
"name": "Frank Ocean"
},
{
"name": "Lil Nas X"
},
{
"name": "Post Malone"
},
{
"name": "Drake"
},
{
"name": "Kanye West"
},
{
"name": "Kendrick Lamar"
},
{
"name": "Tyler, the Creator"
},
{
"name": "Eminem"
},
{
"name": "Childish Gambino"
},
{
"name": "Frank Ocean"
},
{
"name": "Lizzo"
},
{
"name": "Travi$ Scott"
},
{
"name": "A$AP Rocky"
},
{
"name": "Nicki Minaj"
},
{
"name": "xxxtentacion"
}
],
"name": "Hip-Hop, rap"
},
{
"children": [
{
"name": "Arctic Monkeys"
},
{
"name": "Imagine Dragons"
},
{
"name": "The Killers"
},
{
"name": "Gorillaz"
},
{
"name": "The Black Keys"
},
{
"name": "Arctic Monkeys"
},
{
"name": "Imagine Dragons"
},
{
"name": "The Killers"
},
{
"name": "Gorillaz"
},
{
"name": "The Black Keys"
},
{
"name": "Twenty One Pilots"
},
{
"name": "Ellie Goulding"
},
{
"name": "Florence + the Machine"
},
{
"name": "Vampire Weekend"
},
{
"name": "The Smiths"
},
{
"name": "The Strokes"
},
{
"name": "MGMT"
},
{
"name": "Foster the People"
},
{
"name": "Two Door Cinema Club"
},
{
"name": "Cage the Elephant"
},
{
"name": "Arcade Fire"
},
{
"name": "The 1975"
}
],
"name": "indie, alternative"
},
{
"children": [
{
"name": "Ed Sheeran"
},
{
"name": "Tame Impala"
},
{
"name": "Ed Sheeran"
},
{
"name": "Tame Impala"
},
{
"name": "Green Day"
},
{
"name": "Metallica"
},
{
"name": "blink-182"
},
{
"name": "Bon Iver"
},
{
"name": "The Clash"
}
],
"name": "rock, punk rock"
},
{
"children": [
{
"name": "Calvin Harris"
},
{
"name": "The Weeknd"
},
{
"name": "The Chainsmokers"
},
{
"name": "Daft Punk"
},
{
"name": "Marshmello"
},
{
"name": "David Guetta"
},
{
"name": "Calvin Harris"
},
{
"name": "The Weeknd"
},
{
"name": "The Chainsmokers"
},
{
"name": "Daft Punk"
},
{
"name": "Marshmello"
},
{
"name": "David Guetta"
},
{
"name": "Avicii"
},
{
"name": "Kygo"
},
{
"name": "Martin Garrix"
},
{
"name": "Major Lazer"
},
{
"name": "Depeche Mode"
}
],
"name": "electronic, dance"
},
{
"children": [
{
"name": "Queen"
},
{
"name": "The Beatles"
},
{
"name": "David Bowie"
},
{
"name": "Fleetwood Mac"
},
{
"name": "Pink Floyd"
},
{
"name": "The Rolling Stones"
},
{
"name": "Led Zeppelin"
},
{
"name": "Queen"
},
{
"name": "The Beatles"
},
{
"name": "David Bowie"
},
{
"name": "Fleetwood Mac"
},
{
"name": "Pink Floyd"
},
{
"name": "The Rolling Stones"
},
{
"name": "Led Zeppelin"
},
{
"name": "Elton John"
}
],
"name": "classic rock, rock"
},
{
"children": [
{
"name": "Billie Eilish"
},
{
"name": "Ariana Grande"
},
{
"name": "Taylor Swift"
},
{
"name": "Beyoncé"
},
{
"name": "Shawn Mendes"
},
{
"name": "Rihanna"
},
{
"name": "Lana Del Rey"
},
{
"name": "Katy Perry"
},
{
"name": "Lady Gaga"
},
{
"name": "Miley Cyrus"
},
{
"name": "Mark Ronson"
},
{
"name": "Madonna"
},
{
"name": "Lorde"
},
{
"name": "Khalid"
},
{
"name": "Billie Eilish"
},
{
"name": "Ariana Grande"
},
{
"name": "Taylor Swift"
},
{
"name": "Beyoncé"
},
{
"name": "Shawn Mendes"
},
{
"name": "Rihanna"
},
{
"name": "Lana Del Rey"
},
{
"name": "Katy Perry"
},
{
"name": "Lady Gaga"
},
{
"name": "Miley Cyrus"
},
{
"name": "Mark Ronson"
},
{
"name": "Madonna"
},
{
"name": "Lorde"
},
{
"name": "Khalid"
},
{
"name": "Sia"
},
{
"name": "Sam Smith"
},
{
"name": "Halsey"
},
{
"name": "Michael Jackson"
},
{
"name": "Charli XCX"
},
{
"name": "Britney Spears"
},
{
"name": "Dua Lipa"
},
{
"name": "Jonas Brothers"
},
{
"name": "Bruno Mars"
},
{
"name": "Carly Rae Jepsen"
},
{
"name": "P!nk"
},
{
"name": "Adele"
}
],
"name": "pop, female vocalists"
}
],
"name": "Musicians"
}

68
algorithms-miscellaneous-3/src/main/resources/kmeans/radial.html Normal file
View File

@ -0,0 +1,68 @@
<!DOCTYPE html>
<meta charset="utf-8">
<style>
.node circle {
fill: #fff;
stroke: steelblue;
stroke-width: 1.5px;
}
.node {
font: 10px sans-serif;
}
.link {
fill: none;
stroke: #ccc;
stroke-width: 1.5px;
}
</style>
<body>
<script src="http://d3js.org/d3.v3.min.js"></script>
<script>
var diameter = 1100;
var tree = d3.layout.tree()
.size([360, diameter / 2 - 300])
.separation(function (a, b) {
return (a.parent == b.parent ? 1 : 2) / a.depth;
});
var diagonal = d3.svg.diagonal.radial()
.projection(function (d) {
return [d.y, d.x / 180 * Math.PI];
});
var svg = d3.select("body").append("svg")
.attr("width", diameter)
.attr("height", diameter - 150)
.append("g")
.attr("transform", "translate(" + diameter / 2 + "," + diameter / 2 + ")");
d3.json("lastfm.json", function (error, root) {
var nodes = tree.nodes(root),
links = tree.links(nodes);
var link = svg.selectAll(".link")
.data(links)
.enter().append("path")
.attr("class", "link")
.attr("d", diagonal);
var node = svg.selectAll(".node")
.data(nodes)
.enter().append("g")
.attr("class", "node")
.attr("transform", function (d) {
return "rotate(" + (d.x - 90) + ")translate(" + d.y + ")";
})
node.append("circle")
.attr("r", 4.5);
node.append("text")
.attr("dy", ".31em")
.attr("text-anchor", function (d) {
return d.x < 180 ? "start" : "end";
})
.attr("transform", function (d) {
return d.x < 180 ? "translate(8)" : "rotate(180)translate(-8)";
})
.text(function (d) {
return d.name;
});
});
d3.select(self.frameElement).style("height", diameter - 150 + "px");
</script>

29
algorithms-miscellaneous-3/src/test/java/com/baeldung/algorithms/interpolationsearch/InterpolationSearchUnitTest.java Normal file
View File

@ -0,0 +1,29 @@
package com.baeldung.algorithms.interpolationsearch;
import static org.junit.jupiter.api.Assertions.assertEquals;
import org.junit.Before;
import org.junit.Test;
public class InterpolationSearchUnitTest {
private int[] myData;
@Before
public void setUp() {
myData = new int[]{13,21,34,55,69,73,84,101};
}
@Test
public void givenSortedArray_whenLookingFor84_thenReturn6() {
int pos = InterpolationSearch.interpolationSearch(myData, 84);
assertEquals(6, pos);
}
@Test
public void givenSortedArray_whenLookingFor19_thenReturnMinusOne() {
int pos = InterpolationSearch.interpolationSearch(myData, 19);
assertEquals(-1, pos);
}
}

20
algorithms-miscellaneous-3/src/test/java/com/baeldung/algorithms/printtriangles/PrintTriangleExamplesUnitTest.java
View File

@ -9,9 +9,9 @@ import static org.junit.Assert.assertEquals;
@RunWith(JUnitParamsRunner.class)
public class PrintTriangleExamplesUnitTest {
private static Object[][] rightAngledTriangles() {
String expected0 = "";
private static Object[][] rightTriangles() {
String expected0 = "";
String expected2 = "*" + System.lineSeparator()
+ "**" + System.lineSeparator();
@ -39,9 +39,9 @@ public class PrintTriangleExamplesUnitTest {
}
@Test
@Parameters(method = "rightAngledTriangles")
public void whenPrintARightAngledTriangleIsCalled_ThenTheCorrectStringIsReturned(int nrOfRows, String expected) {
String actual = PrintTriangleExamples.printARightAngledTriangle(nrOfRows);
@Parameters(method = "rightTriangles")
public void whenPrintARightTriangleIsCalled_ThenTheCorrectStringIsReturned(int nrOfRows, String expected) {
String actual = PrintTriangleExamples.printARightTriangle(nrOfRows);
assertEquals(expected, actual);
}
@ -81,6 +81,14 @@ public class PrintTriangleExamplesUnitTest {
assertEquals(expected, actual);
}
@Test
@Parameters(method = "isoscelesTriangles")
public void whenPrintAnIsoscelesTriangleUsingStringUtilsIsCalled_ThenTheCorrectStringIsReturned(int nrOfRows, String expected) {
String actual = PrintTriangleExamples.printAnIsoscelesTriangleUsingStringUtils(nrOfRows);
assertEquals(expected, actual);
}
@Test
@Parameters(method = "isoscelesTriangles")

2
algorithms-sorting/README.md
View File

@ -5,3 +5,5 @@
- [Quicksort Algorithm Implementation in Java](https://www.baeldung.com/java-quicksort)
- [Insertion Sort in Java](https://www.baeldung.com/java-insertion-sort)
- [Heap Sort in Java](https://www.baeldung.com/java-heap-sort)
- [Shell Sort in Java](https://www.baeldung.com/java-shell-sort)
- [Counting Sort in Java](https://www.baeldung.com/java-counting-sort)

48
algorithms-sorting/src/main/java/com/baeldung/algorithms/counting/CountingSort.java Normal file
View File

@ -0,0 +1,48 @@
package com.baeldung.algorithms.counting;
import java.util.Arrays;
import java.util.stream.IntStream;
public class CountingSort {
public static int[] sort(int[] input, int k) {
verifyPreconditions(input, k);
if (input.length == 0) return input;
int[] c = countElements(input, k);
int[] sorted = new int[input.length];
for (int i = input.length - 1; i >= 0; i--) {
int current = input[i];
sorted[c[current] - 1] = current;
c[current] -= 1;
}
return sorted;
}
static int[] countElements(int[] input, int k) {
int[] c = new int[k + 1];
Arrays.fill(c, 0);
for (int i : input) {
c[i] += 1;
}
for (int i = 1; i < c.length; i++) {
c[i] += c[i - 1];
}
return c;
}
private static void verifyPreconditions(int[] input, int k) {
if (input == null) {
throw new IllegalArgumentException("Input is required");
}
int min = IntStream.of(input).min().getAsInt();
int max = IntStream.of(input).max().getAsInt();
if (min < 0 || max > k) {
throw new IllegalArgumentException("The input numbers should be between zero and " + k);
}
}
}

2
algorithms-miscellaneous-3/src/main/java/com/baeldung/algorithms/stringsortingbynumber/NaturalOrderComparators.java → algorithms-sorting/src/main/java/com/baeldung/algorithms/sort/bynumber/NaturalOrderComparators.java
View File

@ -1,4 +1,4 @@
package com.baeldung.algorithms.stringsortingbynumber;
package com.baeldung.algorithms.sort.bynumber;
import java.util.Comparator;

32
algorithms-sorting/src/test/java/com/baeldung/algorithms/counting/CountingSortUnitTest.java Normal file
View File

@ -0,0 +1,32 @@
package com.baeldung.algorithms.counting;
import java.util.Arrays;
import static org.junit.jupiter.api.Assertions.assertArrayEquals;
import org.junit.jupiter.api.Test;
class CountingSortUnitTest {
@Test
void countElements_GivenAnArray_ShouldCalculateTheFrequencyArrayAsExpected() {
int k = 5;
int[] input = { 4, 3, 2, 5, 4, 3, 5, 1, 0, 2, 5 };
int[] c = CountingSort.countElements(input, k);
int[] expected = { 1, 2, 4, 6, 8, 11 };
assertArrayEquals(expected, c);
}
@Test
void sort_GivenAnArray_ShouldSortTheInputAsExpected() {
int k = 5;
int[] input = { 4, 3, 2, 5, 4, 3, 5, 1, 0, 2, 5 };
int[] sorted = CountingSort.sort(input, k);
// Our sorting algorithm and Java's should return the same result
Arrays.sort(input);
assertArrayEquals(input, sorted);
}
}

4
algorithms-miscellaneous-3/src/test/java/com/baeldung/algorithms/stringsortingbynumber/NaturalOrderComparatorsUnitTest.java → algorithms-sorting/src/test/java/com/baeldung/algorithms/sort/bynumber/NaturalOrderComparatorsUnitTest.java
View File

@ -1,6 +1,6 @@
package com.baeldung.algorithms.stringsortingbynumber;
package com.baeldung.algorithms.sort.bynumber;
import com.baeldung.algorithms.stringsortingbynumber.NaturalOrderComparators;
import com.baeldung.algorithms.sort.bynumber.NaturalOrderComparators;
import org.junit.Test;
import java.util.ArrayList;

4
apache-olingo/olingo2/pom.xml
View File

@ -4,9 +4,9 @@
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>
<groupId>org.baeldung.examples.olingo2</groupId>
<artifactId>olingo2-sample</artifactId>
<artifactId>olingo2</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>olingo2-sample</name>
<name>olingo2</name>
<description>Sample Olingo 2 Project</description>
<parent>

150
apache-spark/data/iris.data Normal file
View File

@ -0,0 +1,150 @@
5.1,3.5,1.4,0.2,Iris-setosa
4.9,3.0,1.4,0.2,Iris-setosa
4.7,3.2,1.3,0.2,Iris-setosa
4.6,3.1,1.5,0.2,Iris-setosa
5.0,3.6,1.4,0.2,Iris-setosa
5.4,3.9,1.7,0.4,Iris-setosa
4.6,3.4,1.4,0.3,Iris-setosa
5.0,3.4,1.5,0.2,Iris-setosa
4.4,2.9,1.4,0.2,Iris-setosa
4.9,3.1,1.5,0.1,Iris-setosa
5.4,3.7,1.5,0.2,Iris-setosa
4.8,3.4,1.6,0.2,Iris-setosa
4.8,3.0,1.4,0.1,Iris-setosa
4.3,3.0,1.1,0.1,Iris-setosa
5.8,4.0,1.2,0.2,Iris-setosa
5.7,4.4,1.5,0.4,Iris-setosa
5.4,3.9,1.3,0.4,Iris-setosa
5.1,3.5,1.4,0.3,Iris-setosa
5.7,3.8,1.7,0.3,Iris-setosa
5.1,3.8,1.5,0.3,Iris-setosa
5.4,3.4,1.7,0.2,Iris-setosa
5.1,3.7,1.5,0.4,Iris-setosa
4.6,3.6,1.0,0.2,Iris-setosa
5.1,3.3,1.7,0.5,Iris-setosa
4.8,3.4,1.9,0.2,Iris-setosa
5.0,3.0,1.6,0.2,Iris-setosa
5.0,3.4,1.6,0.4,Iris-setosa
5.2,3.5,1.5,0.2,Iris-setosa
5.2,3.4,1.4,0.2,Iris-setosa
4.7,3.2,1.6,0.2,Iris-setosa
4.8,3.1,1.6,0.2,Iris-setosa
5.4,3.4,1.5,0.4,Iris-setosa
5.2,4.1,1.5,0.1,Iris-setosa
5.5,4.2,1.4,0.2,Iris-setosa
4.9,3.1,1.5,0.1,Iris-setosa
5.0,3.2,1.2,0.2,Iris-setosa
5.5,3.5,1.3,0.2,Iris-setosa
4.9,3.1,1.5,0.1,Iris-setosa
4.4,3.0,1.3,0.2,Iris-setosa
5.1,3.4,1.5,0.2,Iris-setosa
5.0,3.5,1.3,0.3,Iris-setosa
4.5,2.3,1.3,0.3,Iris-setosa
4.4,3.2,1.3,0.2,Iris-setosa
5.0,3.5,1.6,0.6,Iris-setosa
5.1,3.8,1.9,0.4,Iris-setosa
4.8,3.0,1.4,0.3,Iris-setosa
5.1,3.8,1.6,0.2,Iris-setosa
4.6,3.2,1.4,0.2,Iris-setosa
5.3,3.7,1.5,0.2,Iris-setosa
5.0,3.3,1.4,0.2,Iris-setosa
7.0,3.2,4.7,1.4,Iris-versicolor
6.4,3.2,4.5,1.5,Iris-versicolor
6.9,3.1,4.9,1.5,Iris-versicolor
5.5,2.3,4.0,1.3,Iris-versicolor
6.5,2.8,4.6,1.5,Iris-versicolor
5.7,2.8,4.5,1.3,Iris-versicolor
6.3,3.3,4.7,1.6,Iris-versicolor
4.9,2.4,3.3,1.0,Iris-versicolor
6.6,2.9,4.6,1.3,Iris-versicolor
5.2,2.7,3.9,1.4,Iris-versicolor
5.0,2.0,3.5,1.0,Iris-versicolor
5.9,3.0,4.2,1.5,Iris-versicolor
6.0,2.2,4.0,1.0,Iris-versicolor
6.1,2.9,4.7,1.4,Iris-versicolor
5.6,2.9,3.6,1.3,Iris-versicolor
6.7,3.1,4.4,1.4,Iris-versicolor
5.6,3.0,4.5,1.5,Iris-versicolor
5.8,2.7,4.1,1.0,Iris-versicolor
6.2,2.2,4.5,1.5,Iris-versicolor
5.6,2.5,3.9,1.1,Iris-versicolor
5.9,3.2,4.8,1.8,Iris-versicolor
6.1,2.8,4.0,1.3,Iris-versicolor
6.3,2.5,4.9,1.5,Iris-versicolor
6.1,2.8,4.7,1.2,Iris-versicolor
6.4,2.9,4.3,1.3,Iris-versicolor
6.6,3.0,4.4,1.4,Iris-versicolor
6.8,2.8,4.8,1.4,Iris-versicolor
6.7,3.0,5.0,1.7,Iris-versicolor
6.0,2.9,4.5,1.5,Iris-versicolor
5.7,2.6,3.5,1.0,Iris-versicolor
5.5,2.4,3.8,1.1,Iris-versicolor
5.5,2.4,3.7,1.0,Iris-versicolor
5.8,2.7,3.9,1.2,Iris-versicolor
6.0,2.7,5.1,1.6,Iris-versicolor
5.4,3.0,4.5,1.5,Iris-versicolor
6.0,3.4,4.5,1.6,Iris-versicolor
6.7,3.1,4.7,1.5,Iris-versicolor
6.3,2.3,4.4,1.3,Iris-versicolor
5.6,3.0,4.1,1.3,Iris-versicolor
5.5,2.5,4.0,1.3,Iris-versicolor
5.5,2.6,4.4,1.2,Iris-versicolor
6.1,3.0,4.6,1.4,Iris-versicolor
5.8,2.6,4.0,1.2,Iris-versicolor
5.0,2.3,3.3,1.0,Iris-versicolor
5.6,2.7,4.2,1.3,Iris-versicolor
5.7,3.0,4.2,1.2,Iris-versicolor
5.7,2.9,4.2,1.3,Iris-versicolor
6.2,2.9,4.3,1.3,Iris-versicolor
5.1,2.5,3.0,1.1,Iris-versicolor
5.7,2.8,4.1,1.3,Iris-versicolor
6.3,3.3,6.0,2.5,Iris-virginica
5.8,2.7,5.1,1.9,Iris-virginica
7.1,3.0,5.9,2.1,Iris-virginica
6.3,2.9,5.6,1.8,Iris-virginica
6.5,3.0,5.8,2.2,Iris-virginica
7.6,3.0,6.6,2.1,Iris-virginica
4.9,2.5,4.5,1.7,Iris-virginica
7.3,2.9,6.3,1.8,Iris-virginica
6.7,2.5,5.8,1.8,Iris-virginica
7.2,3.6,6.1,2.5,Iris-virginica
6.5,3.2,5.1,2.0,Iris-virginica
6.4,2.7,5.3,1.9,Iris-virginica
6.8,3.0,5.5,2.1,Iris-virginica
5.7,2.5,5.0,2.0,Iris-virginica
5.8,2.8,5.1,2.4,Iris-virginica
6.4,3.2,5.3,2.3,Iris-virginica
6.5,3.0,5.5,1.8,Iris-virginica
7.7,3.8,6.7,2.2,Iris-virginica
7.7,2.6,6.9,2.3,Iris-virginica
6.0,2.2,5.0,1.5,Iris-virginica
6.9,3.2,5.7,2.3,Iris-virginica
5.6,2.8,4.9,2.0,Iris-virginica
7.7,2.8,6.7,2.0,Iris-virginica
6.3,2.7,4.9,1.8,Iris-virginica
6.7,3.3,5.7,2.1,Iris-virginica
7.2,3.2,6.0,1.8,Iris-virginica
6.2,2.8,4.8,1.8,Iris-virginica
6.1,3.0,4.9,1.8,Iris-virginica
6.4,2.8,5.6,2.1,Iris-virginica
7.2,3.0,5.8,1.6,Iris-virginica
7.4,2.8,6.1,1.9,Iris-virginica
7.9,3.8,6.4,2.0,Iris-virginica
6.4,2.8,5.6,2.2,Iris-virginica
6.3,2.8,5.1,1.5,Iris-virginica
6.1,2.6,5.6,1.4,Iris-virginica
7.7,3.0,6.1,2.3,Iris-virginica
6.3,3.4,5.6,2.4,Iris-virginica
6.4,3.1,5.5,1.8,Iris-virginica
6.0,3.0,4.8,1.8,Iris-virginica
6.9,3.1,5.4,2.1,Iris-virginica
6.7,3.1,5.6,2.4,Iris-virginica
6.9,3.1,5.1,2.3,Iris-virginica
5.8,2.7,5.1,1.9,Iris-virginica
6.8,3.2,5.9,2.3,Iris-virginica
6.7,3.3,5.7,2.5,Iris-virginica
6.7,3.0,5.2,2.3,Iris-virginica
6.3,2.5,5.0,1.9,Iris-virginica
6.5,3.0,5.2,2.0,Iris-virginica
6.2,3.4,5.4,2.3,Iris-virginica
5.9,3.0,5.1,1.8,Iris-virginica

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apache-spark/model/logistic-regression/metadata/part-00000 Normal file
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@ -0,0 +1 @@
{"class":"org.apache.spark.mllib.classification.LogisticRegressionModel","version":"1.0","numFeatures":4,"numClasses":3}

132
apache-spark/pom.xml
View File

@ -1,31 +1,32 @@
<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>
<groupId>com.baeldung</groupId>
<artifactId>apache-spark</artifactId>
<version>1.0-SNAPSHOT</version>
<name>apache-spark</name>
<packaging>jar</packaging>
<url>http://maven.apache.org</url>
<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>
<groupId>com.baeldung</groupId>
<artifactId>apache-spark</artifactId>
<version>1.0-SNAPSHOT</version>
<name>apache-spark</name>
<packaging>jar</packaging>
<url>http://maven.apache.org</url>
<parent>
<groupId>com.baeldung</groupId>
<artifactId>parent-modules</artifactId>
<version>1.0.0-SNAPSHOT</version>
</parent>
<parent>
<groupId>com.baeldung</groupId>
<artifactId>parent-modules</artifactId>
<version>1.0.0-SNAPSHOT</version>
</parent>
<dependencies>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-core_2.11</artifactId>
<version>${org.apache.spark.spark-core.version}</version>
<scope>provided</scope>
</dependency>
<dependencies>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-sql_2.11</artifactId>
<version>${org.apache.spark.spark-sql.version}</version>
<scope>provided</scope>
<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-sql.version}</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.apache.spark</groupId>
@ -33,6 +34,12 @@
<version>${org.apache.spark.spark-streaming.version}</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-mllib_2.11</artifactId>
<version>${org.apache.spark.spark-mllib.version}</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-streaming-kafka-0-10_2.11</artifactId>
@ -48,46 +55,47 @@
<artifactId>spark-cassandra-connector-java_2.11</artifactId>
<version>${com.datastax.spark.spark-cassandra-connector-java.version}</version>
</dependency>
</dependencies>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>${maven-compiler-plugin.version}</version>
<configuration>
<source>${java.version}</source>
<target>${java.version}</target>
</configuration>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
</plugins>
</build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>${maven-compiler-plugin.version}</version>
<configuration>
<source>${java.version}</source>
<target>${java.version}</target>
</configuration>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
</plugins>
</build>
<properties>
<org.apache.spark.spark-core.version>2.3.0</org.apache.spark.spark-core.version>
<org.apache.spark.spark-sql.version>2.3.0</org.apache.spark.spark-sql.version>
<org.apache.spark.spark-streaming.version>2.3.0</org.apache.spark.spark-streaming.version>
<org.apache.spark.spark-streaming-kafka.version>2.3.0</org.apache.spark.spark-streaming-kafka.version>
<com.datastax.spark.spark-cassandra-connector.version>2.3.0</com.datastax.spark.spark-cassandra-connector.version>
<com.datastax.spark.spark-cassandra-connector-java.version>1.5.2</com.datastax.spark.spark-cassandra-connector-java.version>
<properties>
<org.apache.spark.spark-core.version>2.3.0</org.apache.spark.spark-core.version>
<org.apache.spark.spark-sql.version>2.3.0</org.apache.spark.spark-sql.version>
<org.apache.spark.spark-streaming.version>2.3.0</org.apache.spark.spark-streaming.version>
<org.apache.spark.spark-mllib.version>2.3.0</org.apache.spark.spark-mllib.version>
<org.apache.spark.spark-streaming-kafka.version>2.3.0</org.apache.spark.spark-streaming-kafka.version>
<com.datastax.spark.spark-cassandra-connector.version>2.3.0</com.datastax.spark.spark-cassandra-connector.version>
<com.datastax.spark.spark-cassandra-connector-java.version>1.5.2</com.datastax.spark.spark-cassandra-connector-java.version>
<maven-compiler-plugin.version>3.2</maven-compiler-plugin.version>
</properties>
</properties>
</project>

111
apache-spark/src/main/java/com/baeldung/ml/MachineLearningApp.java Normal file
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@ -0,0 +1,111 @@
package com.baeldung.ml;
import java.util.HashMap;
import java.util.Map;
import org.apache.log4j.Level;
import org.apache.log4j.Logger;
import org.apache.spark.SparkConf;
import org.apache.spark.api.java.JavaPairRDD;
import org.apache.spark.api.java.JavaRDD;
import org.apache.spark.api.java.JavaSparkContext;
import org.apache.spark.mllib.classification.LogisticRegressionModel;
import org.apache.spark.mllib.classification.LogisticRegressionWithLBFGS;
import org.apache.spark.mllib.evaluation.MulticlassMetrics;
import org.apache.spark.mllib.linalg.Matrix;
import org.apache.spark.mllib.linalg.Vector;
import org.apache.spark.mllib.linalg.Vectors;
import org.apache.spark.mllib.regression.LabeledPoint;
import org.apache.spark.mllib.stat.MultivariateStatisticalSummary;
import org.apache.spark.mllib.stat.Statistics;
import scala.Tuple2;
public class MachineLearningApp {
public static void main(String[] args) {
// 1. Setting the Spark Context
SparkConf conf = new SparkConf().setAppName("Main")
.setMaster("local[2]")
.set("spark.executor.memory", "3g")
.set("spark.driver.memory", "3g");
JavaSparkContext sc = new JavaSparkContext(conf);
Logger.getLogger("org")
.setLevel(Level.OFF);
Logger.getLogger("akka")
.setLevel(Level.OFF);
// 2. Loading the Data-set
String dataFile = "data\\iris.data";
JavaRDD<String> data = sc.textFile(dataFile);
// 3. Exploratory Data Analysis
// 3.1. Creating Vector of Input Data
JavaRDD<Vector> inputData = data.map(line -> {
String[] parts = line.split(",");
double[] v = new double[parts.length - 1];
for (int i = 0; i < parts.length - 1; i++) {
v[i] = Double.parseDouble(parts[i]);
}
return Vectors.dense(v);
});
// 3.2. Performing Statistical Analysis
MultivariateStatisticalSummary summary = Statistics.colStats(inputData.rdd());
System.out.println("Summary Mean:");
System.out.println(summary.mean());
System.out.println("Summary Variance:");
System.out.println(summary.variance());
System.out.println("Summary Non-zero:");
System.out.println(summary.numNonzeros());
// 3.3. Performing Correlation Analysis
Matrix correlMatrix = Statistics.corr(inputData.rdd(), "pearson");
System.out.println("Correlation Matrix:");
System.out.println(correlMatrix.toString());
// 4. Data Preparation
// 4.1. Creating Map for Textual Output Labels
Map<String, Integer> map = new HashMap<String, Integer>();
map.put("Iris-setosa", 0);
map.put("Iris-versicolor", 1);
map.put("Iris-virginica", 2);
// 4.2. Creating LabeledPoint of Input and Output Data
JavaRDD<LabeledPoint> parsedData = data.map(line -> {
String[] parts = line.split(",");
double[] v = new double[parts.length - 1];
for (int i = 0; i < parts.length - 1; i++) {
v[i] = Double.parseDouble(parts[i]);
}
return new LabeledPoint(map.get(parts[parts.length - 1]), Vectors.dense(v));
});
// 5. Data Splitting into 80% Training and 20% Test Sets
JavaRDD<LabeledPoint>[] splits = parsedData.randomSplit(new double[] { 0.8, 0.2 }, 11L);
JavaRDD<LabeledPoint> trainingData = splits[0].cache();
JavaRDD<LabeledPoint> testData = splits[1];
// 6. Modeling
// 6.1. Model Training
LogisticRegressionModel model = new LogisticRegressionWithLBFGS().setNumClasses(3)
.run(trainingData.rdd());
// 6.2. Model Evaluation
JavaPairRDD<Object, Object> predictionAndLabels = testData.mapToPair(p -> new Tuple2<>(model.predict(p.features()), p.label()));
MulticlassMetrics metrics = new MulticlassMetrics(predictionAndLabels.rdd());
double accuracy = metrics.accuracy();
System.out.println("Model Accuracy on Test Data: " + accuracy);
// 7. Model Saving and Loading
// 7.1. Model Saving
model.save(sc.sc(), "model\\logistic-regression");
// 7.2. Model Loading
LogisticRegressionModel sameModel = LogisticRegressionModel.load(sc.sc(), "model\\logistic-regression");
// 7.3. Prediction on New Data
Vector newData = Vectors.dense(new double[] { 1, 1, 1, 1 });
double prediction = sameModel.predict(newData);
System.out.println("Model Prediction on New Data = " + prediction);
// 8. Clean-up
sc.close();
}
}

3
bazel/README.md Normal file
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@ -0,0 +1,3 @@
## Relevant Articles:
- [Building Java Applications with Bazel](https://www.baeldung.com/bazel-build-tool)

31
bazel/WORKSPACE Normal file
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@ -0,0 +1,31 @@
load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_jar")
load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
RULES_JVM_EXTERNAL_TAG = "2.0.1"
RULES_JVM_EXTERNAL_SHA = "55e8d3951647ae3dffde22b4f7f8dee11b3f70f3f89424713debd7076197eaca"
http_archive(
name = "rules_jvm_external",
strip_prefix = "rules_jvm_external-%s" % RULES_JVM_EXTERNAL_TAG,
sha256 = RULES_JVM_EXTERNAL_SHA,
url = "https://github.com/bazelbuild/rules_jvm_external/archive/%s.zip" % RULES_JVM_EXTERNAL_TAG,
)
load("@rules_jvm_external//:defs.bzl", "maven_install")
maven_install(
artifacts = [
"org.apache.commons:commons-lang3:3.9"
],
repositories = [
"https://repo1.maven.org/maven2",
]
)
http_jar (
name = "apache-commons-lang",
url = "https://repo1.maven.org/maven2/org/apache/commons/commons-lang3/3.9/commons-lang3-3.9.jar"
)

7
bazel/bazelapp/BUILD Normal file
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@ -0,0 +1,7 @@
java_binary (
name = "BazelApp",
srcs = glob(["src/main/java/com/baeldung/*.java"]),
main_class = "com.baeldung.BazelApp",
deps = ["//bazelgreeting:greeter", "@maven//:org_apache_commons_commons_lang3"]
)

29
bazel/bazelapp/pom.xml Normal file
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@ -0,0 +1,29 @@
<?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>bazelapp</artifactId>
<name>bazelapp</name>
<parent>
<artifactId>bazel</artifactId>
<groupId>com.baeldung</groupId>
<version>1.0.0-SNAPSHOT</version>
</parent>
<dependencies>
<dependency>
<groupId>com.baeldung</groupId>
<artifactId>bazelgreeting</artifactId>
<version>1.0.0-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.9</version>
</dependency>
</dependencies>
</project>

15
bazel/bazelapp/src/main/java/com/baeldung/BazelApp.java Normal file
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@ -0,0 +1,15 @@
package com.baeldung;
import com.baeldung.Greetings;
import org.apache.commons.lang3.StringUtils;
public class BazelApp {
public static void main(String ... args) {
Greetings greetings = new Greetings();
System.out.println(greetings.greet("Bazel"));
System.out.println(StringUtils.lowerCase("Bazel"));
}
}

6
bazel/bazelgreeting/BUILD Normal file
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@ -0,0 +1,6 @@
java_library (
name = "greeter",
srcs = glob(["src/main/java/com/baeldung/*.java"]),
visibility = ["//bazelapp:__pkg__"]
)

16
bazel/bazelgreeting/pom.xml Normal file
View File

@ -0,0 +1,16 @@
<?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>bazelgreeting</artifactId>
<name>bazelgreeting</name>
<parent>
<artifactId>bazel</artifactId>
<groupId>com.baeldung</groupId>
<version>1.0.0-SNAPSHOT</version>
</parent>
</project>

8
bazel/bazelgreeting/src/main/java/com/baeldung/Greetings.java Normal file
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@ -0,0 +1,8 @@
package com.baeldung;
public class Greetings {
public String greet(String name) {
return "Hello ".concat(name);
}
}

22
bazel/pom.xml Normal file
View File

@ -0,0 +1,22 @@
<?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>bazel</artifactId>
<packaging>pom</packaging>
<name>bazel</name>
<parent>
<artifactId>parent-modules</artifactId>
<groupId>com.baeldung</groupId>
<version>1.0.0-SNAPSHOT</version>
</parent>
<modules>
<module>bazelgreeting</module>
<module>bazelapp</module>
</modules>
</project>

1
core-groovy-2/README.md
View File

@ -8,3 +8,4 @@
- [Pattern Matching in Strings in Groovy](https://www.baeldung.com/groovy-pattern-matching)
- [Working with XML in Groovy](https://www.baeldung.com/groovy-xml)
- [Integrating Groovy into Java Applications](https://www.baeldung.com/groovy-java-applications)
- [Concatenate Strings with Groovy](https://www.baeldung.com/groovy-concatenate-strings)

2
core-java-modules/core-java-arrays-2/README.MD
View File

@ -1,3 +1,5 @@
## Relevant Articles
- [Extending an Array’s Length](https://www.baeldung.com/java-array-add-element-at-the-end)
- [Checking If an Array Is Sorted in Java](https://www.baeldung.com/java-check-sorted-array)
- [Looping Diagonally Through a 2d Java Array](https://www.baeldung.com/java-loop-diagonal-array)

12
core-java-modules/core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/mutex/SequenceGenerator.java Normal file
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@ -0,0 +1,12 @@
package com.baeldung.concurrent.mutex;
public class SequenceGenerator {
private int currentValue = 0;
public int getNextSequence() {
currentValue = currentValue + 1;
return currentValue;
}
}

19
core-java-modules/core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/mutex/SequenceGeneratorUsingMonitor.java Normal file
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@ -0,0 +1,19 @@
package com.baeldung.concurrent.mutex;
import com.google.common.util.concurrent.Monitor;
public class SequenceGeneratorUsingMonitor extends SequenceGenerator {
private Monitor mutex = new Monitor();
@Override
public int getNextSequence() {
mutex.enter();
try {
return super.getNextSequence();
} finally {
mutex.leave();
}
}
}

19
core-java-modules/core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/mutex/SequenceGeneratorUsingReentrantLock.java Normal file
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@ -0,0 +1,19 @@
package com.baeldung.concurrent.mutex;
import java.util.concurrent.locks.ReentrantLock;
public class SequenceGeneratorUsingReentrantLock extends SequenceGenerator {
private ReentrantLock mutex = new ReentrantLock();
@Override
public int getNextSequence() {
try {
mutex.lock();
return super.getNextSequence();
} finally {
mutex.unlock();
}
}
}

21
core-java-modules/core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/mutex/SequenceGeneratorUsingSemaphore.java Normal file
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@ -0,0 +1,21 @@
package com.baeldung.concurrent.mutex;
import java.util.concurrent.Semaphore;
public class SequenceGeneratorUsingSemaphore extends SequenceGenerator {
private Semaphore mutex = new Semaphore(1);
@Override
public int getNextSequence() {
try {
mutex.acquire();
return super.getNextSequence();
} catch (InterruptedException e) {
throw new RuntimeException("Exception in critical section.", e);
} finally {
mutex.release();
}
}
}

14
core-java-modules/core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/mutex/SequenceGeneratorUsingSynchronizedBlock.java Normal file
View File

@ -0,0 +1,14 @@
package com.baeldung.concurrent.mutex;
public class SequenceGeneratorUsingSynchronizedBlock extends SequenceGenerator {
private Object mutex = new Object();
@Override
public int getNextSequence() {
synchronized (mutex) {
return super.getNextSequence();
}
}
}

10
core-java-modules/core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/mutex/SequenceGeneratorUsingSynchronizedMethod.java Normal file
View File

@ -0,0 +1,10 @@
package com.baeldung.concurrent.mutex;
public class SequenceGeneratorUsingSynchronizedMethod extends SequenceGenerator {
@Override
public synchronized int getNextSequence() {
return super.getNextSequence();
}
}

2
core-java-modules/core-java-concurrency-basic/src/test/java/com/baeldung/java8/Java8ExecutorServiceIntegrationTest.java → core-java-modules/core-java-concurrency-basic/src/test/java/com/baeldung/concurrent/executorservice/Java8ExecutorServiceIntegrationTest.java
View File

@ -1,4 +1,4 @@
package com.baeldung.java8;
package com.baeldung.concurrent.executorservice;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;

80
core-java-modules/core-java-concurrency-basic/src/test/java/com/baeldung/concurrent/mutex/MutexUnitTest.java Normal file
View File

@ -0,0 +1,80 @@
package com.baeldung.concurrent.mutex;
import java.util.ArrayList;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import org.junit.Assert;
import org.junit.Test;
public class MutexUnitTest {
// @Test
// This test verifies the race condition use case, it may pass or fail based on execution environment
// Uncomment @Test to run it
public void givenUnsafeSequenceGenerator_whenRaceCondition_thenUnexpectedBehavior() throws Exception {
int count = 1000;
Set<Integer> uniqueSequences = getUniqueSequences(new SequenceGenerator(), count);
Assert.assertNotEquals(count, uniqueSequences.size());
}
@Test
public void givenSequenceGeneratorUsingSynchronizedMethod_whenRaceCondition_thenSuccess() throws Exception {
int count = 1000;
Set<Integer> uniqueSequences = getUniqueSequences(new SequenceGeneratorUsingSynchronizedMethod(), count);
Assert.assertEquals(count, uniqueSequences.size());
}
@Test
public void givenSequenceGeneratorUsingSynchronizedBlock_whenRaceCondition_thenSuccess() throws Exception {
int count = 1000;
Set<Integer> uniqueSequences = getUniqueSequences(new SequenceGeneratorUsingSynchronizedBlock(), count);
Assert.assertEquals(count, uniqueSequences.size());
}
@Test
public void givenSequenceGeneratorUsingReentrantLock_whenRaceCondition_thenSuccess() throws Exception {
int count = 1000;
Set<Integer> uniqueSequences = getUniqueSequences(new SequenceGeneratorUsingReentrantLock(), count);
Assert.assertEquals(count, uniqueSequences.size());
}
@Test
public void givenSequenceGeneratorUsingSemaphore_whenRaceCondition_thenSuccess() throws Exception {
int count = 1000;
Set<Integer> uniqueSequences = getUniqueSequences(new SequenceGeneratorUsingSemaphore(), count);
Assert.assertEquals(count, uniqueSequences.size());
}
@Test
public void givenSequenceGeneratorUsingMonitor_whenRaceCondition_thenSuccess() throws Exception {
int count = 1000;
Set<Integer> uniqueSequences = getUniqueSequences(new SequenceGeneratorUsingMonitor(), count);
Assert.assertEquals(count, uniqueSequences.size());
}
private Set<Integer> getUniqueSequences(SequenceGenerator generator, int count) throws Exception {
ExecutorService executor = Executors.newFixedThreadPool(3);
Set<Integer> uniqueSequences = new LinkedHashSet<>();
List<Future<Integer>> futures = new ArrayList<>();
for (int i = 0; i < count; i++) {
futures.add(executor.submit(generator::getNextSequence));
}
for (Future<Integer> future : futures) {
uniqueSequences.add(future.get());
}
executor.awaitTermination(1, TimeUnit.SECONDS);
executor.shutdown();
return uniqueSequences;
}
}

43
core-java-modules/core-java-exceptions/src/main/java/com/baeldung/exceptions/CheckedUncheckedExceptions.java Normal file
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@ -0,0 +1,43 @@
package com.baeldung.exceptions;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
public class CheckedUncheckedExceptions {
public static void checkedExceptionWithThrows() throws FileNotFoundException {
File file = new File("not_existing_file.txt");
FileInputStream stream = new FileInputStream(file);
}
public static void checkedExceptionWithTryCatch() {
File file = new File("not_existing_file.txt");
try {
FileInputStream stream = new FileInputStream(file);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
public static int divideByZero() {
int numerator = 1;
int denominator = 0;
return numerator / denominator;
}
public static void checkFile(String fileName) throws IncorrectFileNameException {
if (fileName == null || fileName.isEmpty()) {
throw new NullOrEmptyException("The filename is null.");
}
if (!isCorrectFileName(fileName)) {
throw new IncorrectFileNameException("Incorrect filename : " + fileName);
}
}
private static boolean isCorrectFileName(String fileName) {
if (fileName.equals("wrongFileName.txt"))
return false;
else
return true;
}
}

13
core-java-modules/core-java-exceptions/src/main/java/com/baeldung/exceptions/IncorrectFileNameException.java Normal file
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@ -0,0 +1,13 @@
package com.baeldung.exceptions;
public class IncorrectFileNameException extends Exception {
private static final long serialVersionUID = 1L;
public IncorrectFileNameException(String errorMessage) {
super(errorMessage);
}
public IncorrectFileNameException(String errorMessage, Throwable thr) {
super(errorMessage, thr);
}
}

14
core-java-modules/core-java-exceptions/src/main/java/com/baeldung/exceptions/NullOrEmptyException.java Normal file
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@ -0,0 +1,14 @@
package com.baeldung.exceptions;
public class NullOrEmptyException extends RuntimeException {
private static final long serialVersionUID = 1L;
public NullOrEmptyException(String errorMessage) {
super(errorMessage);
}
public NullOrEmptyException(String errorMessage, Throwable thr) {
super(errorMessage, thr);
}
}

55
core-java-modules/core-java-exceptions/src/test/java/com/baeldung/exceptions/CheckedUncheckedExceptionsUnitTest.java Normal file
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@ -0,0 +1,55 @@
package com.baeldung.exceptions;
import static org.junit.jupiter.api.Assertions.assertThrows;
import java.io.FileNotFoundException;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;
/**
* Tests the {@link CheckedUncheckedExceptions}.
*/
public class CheckedUncheckedExceptionsUnitTest {
@Test
public void whenFileNotExist_thenThrowException() {
assertThrows(FileNotFoundException.class, () -> {
CheckedUncheckedExceptions.checkedExceptionWithThrows();
});
}
@Test
public void whenTryCatchExcetpion_thenSuccess() {
try {
CheckedUncheckedExceptions.checkedExceptionWithTryCatch();
} catch (Exception e) {
Assertions.fail(e.getMessage());
}
}
@Test
public void whenDivideByZero_thenThrowException() {
assertThrows(ArithmeticException.class, () -> {
CheckedUncheckedExceptions.divideByZero();
});
}
@Test
public void whenInvalidFile_thenThrowException() {
assertThrows(IncorrectFileNameException.class, () -> {
CheckedUncheckedExceptions.checkFile("wrongFileName.txt");
});
}
@Test
public void whenNullOrEmptyFile_thenThrowException() {
assertThrows(NullOrEmptyException.class, () -> {
CheckedUncheckedExceptions.checkFile(null);
});
assertThrows(NullOrEmptyException.class, () -> {
CheckedUncheckedExceptions.checkFile("");
});
}
}

3
core-java-modules/core-java-io-2/.gitignore vendored Normal file
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@ -0,0 +1,3 @@
# Intellij
.idea/
*.iml

279
core-java-modules/core-java-io-2/pom.xml Normal file
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@ -0,0 +1,279 @@
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>core-java-io-2</artifactId>
<version>0.1.0-SNAPSHOT</version>
<name>core-java-io-2</name>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung</groupId>
<artifactId>parent-java</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../../parent-java</relativePath>
</parent>
<dependencies>
<!-- utils -->
<dependency>
<groupId>net.sourceforge.collections</groupId>
<artifactId>collections-generic</artifactId>
<version>${collections-generic.version}</version>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-collections4</artifactId>
<version>${commons-collections4.version}</version>
</dependency>
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>${commons-io.version}</version>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>${commons-lang3.version}</version>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-math3</artifactId>
<version>${commons-math3.version}</version>
</dependency>
<dependency>
<groupId>org.decimal4j</groupId>
<artifactId>decimal4j</artifactId>
<version>${decimal4j.version}</version>
</dependency>
<dependency>
<groupId>org.bouncycastle</groupId>
<artifactId>bcprov-jdk15on</artifactId>
<version>${bouncycastle.version}</version>
</dependency>
<dependency>
<groupId>org.unix4j</groupId>
<artifactId>unix4j-command</artifactId>
<version>${unix4j.version}</version>
</dependency>
<dependency>
<groupId>com.googlecode.grep4j</groupId>
<artifactId>grep4j</artifactId>
<version>${grep4j.version}</version>
</dependency>
<!-- web -->
<!-- marshalling -->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>${jackson.version}</version>
</dependency>
<!-- logging -->
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>${log4j.version}</version>
</dependency>
<dependency> <!-- needed to bridge to slf4j for projects that use the log4j APIs directly -->
<groupId>org.slf4j</groupId>
<artifactId>log4j-over-slf4j</artifactId>
<version>${org.slf4j.version}</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>${lombok.version}</version>
<scope>provided</scope>
</dependency>
<!-- test scoped -->
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<version>${assertj.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.jayway.awaitility</groupId>
<artifactId>awaitility</artifactId>
<version>${avaitility.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>commons-codec</groupId>
<artifactId>commons-codec</artifactId>
<version>${commons-codec.version}</version>
</dependency>
<dependency>
<groupId>org.javamoney</groupId>
<artifactId>moneta</artifactId>
<version>${moneta.version}</version>
</dependency>
<dependency>
<groupId>org.owasp.esapi</groupId>
<artifactId>esapi</artifactId>
<version>${esapi.version}</version>
</dependency>
<dependency>
<groupId>com.sun.messaging.mq</groupId>
<artifactId>fscontext</artifactId>
<version>${fscontext.version}</version>
</dependency>
<dependency>
<groupId>com.codepoetics</groupId>
<artifactId>protonpack</artifactId>
<version>${protonpack.version}</version>
</dependency>
<dependency>
<groupId>one.util</groupId>
<artifactId>streamex</artifactId>
<version>${streamex.version}</version>
</dependency>
<dependency>
<groupId>io.vavr</groupId>
<artifactId>vavr</artifactId>
<version>${vavr.version}</version>
</dependency>
<dependency>
<groupId>org.openjdk.jmh</groupId>
<artifactId>jmh-core</artifactId>
<version>${jmh-core.version}</version>
</dependency>
<dependency>
<groupId>org.openjdk.jmh</groupId>
<artifactId>jmh-generator-annprocess</artifactId>
<version>${jmh-generator-annprocess.version}</version>
</dependency>
<dependency>
<groupId>org.hsqldb</groupId>
<artifactId>hsqldb</artifactId>
<version>${hsqldb.version}</version>
<scope>runtime</scope>
</dependency>
<!-- https://mvnrepository.com/artifact/org.asynchttpclient/async-http-client -->
<dependency>
<groupId>org.asynchttpclient</groupId>
<artifactId>async-http-client</artifactId>
<version>${async-http-client.version}</version>
</dependency>
<dependency>
<groupId>com.opencsv</groupId>
<artifactId>opencsv</artifactId>
<version>${opencsv.version}</version>
<scope>test</scope>
</dependency>
<!-- Mime Type Resolution Libraries -->
<dependency>
<groupId>org.apache.tika</groupId>
<artifactId>tika-core</artifactId>
<version>${tika.version}</version>
</dependency>
<dependency>
<groupId>net.sf.jmimemagic</groupId>
<artifactId>jmimemagic</artifactId>
<version>${jmime-magic.version}</version>
</dependency>
</dependencies>
<build>
<finalName>core-java-io-2</finalName>
<resources>
<resource>
<directory>src/main/resources</directory>
<filtering>true</filtering>
</resource>
</resources>
<plugins>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>exec-maven-plugin</artifactId>
<version>${exec-maven-plugin.version}</version>
<configuration>
<executable>java</executable>
<mainClass>com.baeldung.outofmemoryerror.OutOfMemoryGCLimitExceed</mainClass>
<arguments>
<argument>-Xmx300m</argument>
<argument>-XX:+UseParallelGC</argument>
<argument>-classpath</argument>
<classpath />
<argument>com.baeldung.outofmemoryerror.OutOfMemoryGCLimitExceed</argument>
</arguments>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-javadoc-plugin</artifactId>
<version>${maven-javadoc-plugin.version}</version>
<configuration>
<source>${maven.compiler.source}</source>
<target>${maven.compiler.target}</target>
</configuration>
</plugin>
</plugins>
</build>
<profiles>
<profile>
<id>integration</id>
<build>
<plugins>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>exec-maven-plugin</artifactId>
<executions>
<execution>
<id>run-benchmarks</id>
<!-- <phase>integration-test</phase> -->
<phase>none</phase>
<goals>
<goal>exec</goal>
</goals>
<configuration>
<classpathScope>test</classpathScope>
<executable>java</executable>
<arguments>
<argument>-classpath</argument>
<classpath />
<argument>org.openjdk.jmh.Main</argument>
<argument>.*</argument>
</arguments>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</profile>
</profiles>
<properties>
<!-- util -->
<bouncycastle.version>1.55</bouncycastle.version>
<commons-codec.version>1.10</commons-codec.version>
<commons-math3.version>3.6.1</commons-math3.version>
<decimal4j.version>1.0.3</decimal4j.version>
<commons-collections4.version>4.1</commons-collections4.version>
<collections-generic.version>4.01</collections-generic.version>
<unix4j.version>0.4</unix4j.version>
<grep4j.version>1.8.7</grep4j.version>
<fscontext.version>4.6-b01</fscontext.version>
<protonpack.version>1.13</protonpack.version>
<streamex.version>0.6.5</streamex.version>
<vavr.version>0.9.0</vavr.version>
<opencsv.version>4.1</opencsv.version>
<!-- testing -->
<assertj.version>3.6.1</assertj.version>
<avaitility.version>1.7.0</avaitility.version>
<!-- maven plugins -->
<maven-javadoc-plugin.version>3.0.0-M1</maven-javadoc-plugin.version>
<hsqldb.version>2.4.0</hsqldb.version>
<esapi.version>2.1.0.1</esapi.version>
<jmh-generator-annprocess.version>1.19</jmh-generator-annprocess.version>
<async-http-client.version>2.4.5</async-http-client.version>
<!-- Mime Type Libraries -->
<tika.version>1.18</tika.version>
<jmime-magic.version>0.1.5</jmime-magic.version>
</properties>
</project>

57
core-java-modules/core-java-io-2/src/main/java/com/baeldung/filereader/FileReaderExample.java Normal file
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@ -0,0 +1,57 @@
package com.baeldung.filereader;
import java.io.*;
public class FileReaderExample {
public static String readAllCharactersOneByOne(Reader reader) throws IOException {
StringBuilder content = new StringBuilder();
int nextChar;
while ((nextChar = reader.read()) != -1) {
content.append((char) nextChar);
}
return String.valueOf(content);
}
public static String readMultipleCharacters(Reader reader, int length) throws IOException {
char[] buffer = new char[length];
int charactersRead = reader.read(buffer, 0, length);
if (charactersRead != -1) {
return new String(buffer, 0, charactersRead);
} else {
return "";
}
}
public static String readFile(String path) {
FileReader fileReader = null;
try {
fileReader = new FileReader(path);
return readAllCharactersOneByOne(fileReader);
} catch (IOException e) {
e.printStackTrace();
} finally {
if (fileReader != null) {
try {
fileReader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return null;
}
public static String readFileUsingTryWithResources(String path) {
try (FileReader fileReader = new FileReader(path)) {
return readAllCharactersOneByOne(fileReader);
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
}

62
core-java-modules/core-java-io-2/src/test/java/com/baeldung/filereader/FileReaderExampleUnitTest.java Normal file
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@ -0,0 +1,62 @@
package com.baeldung.filereader;
import org.junit.Assert;
import org.junit.Test;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
public class FileReaderExampleUnitTest {
private static final String FILE_PATH = "src/test/resources/HelloWorld.txt";
@Test
public void givenFileReader_whenReadAllCharacters_thenReturnsContent() throws IOException {
String expectedText = "Hello, World!";
File file = new File(FILE_PATH);
FileReader fileReader = null;
try {
fileReader = new FileReader(file);
String content = FileReaderExample.readAllCharactersOneByOne(fileReader);
Assert.assertEquals(expectedText, content);
} finally {
if (fileReader != null) {
fileReader.close();
}
}
}
@Test
public void givenFileReader_whenReadMultipleCharacters_thenReturnsContent() throws IOException {
String expectedText = "Hello";
File file = new File(FILE_PATH);
FileReader fileReader = null;
try {
fileReader = new FileReader(file);
String content = FileReaderExample.readMultipleCharacters(fileReader, 5);
Assert.assertEquals(expectedText, content);
} finally {
if (fileReader != null) {
fileReader.close();
}
}
}
@Test
public void whenReadFile_thenReturnsContent() {
String expectedText = "Hello, World!";
String content = FileReaderExample.readFile(FILE_PATH);
Assert.assertEquals(expectedText, content);
}
@Test
public void whenReadFileUsingTryWithResources_thenReturnsContent() {
String expectedText = "Hello, World!";
String content = FileReaderExample.readFileUsingTryWithResources(FILE_PATH);
Assert.assertEquals(expectedText, content);
}
}

1
core-java-modules/core-java-io-2/src/test/resources/HelloWorld.txt Normal file
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@ -0,0 +1 @@
Hello, World!

2
core-java-modules/core-java-io/src/test/java/org/baeldung/java/io/JavaWriteToFileUnitTest.java → core-java-modules/core-java-io/src/test/java/org/baeldung/writetofile/JavaWriteToFileUnitTest.java
View File

@ -1,4 +1,4 @@
package org.baeldung.java.io;
package org.baeldung.writetofile;
import static org.junit.Assert.assertEquals;

66
core-java-modules/core-java-jndi/pom.xml Normal file
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@ -0,0 +1,66 @@
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.baeldung.jndi</groupId>
<artifactId>core-java-jndi</artifactId>
<version>1.0-SNAPSHOT</version>
<name>core-java-jndi</name>
<parent>
<groupId>com.baeldung</groupId>
<artifactId>parent-modules</artifactId>
<version>1.0.0-SNAPSHOT</version>
<relativePath>../../</relativePath>
</parent>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter</artifactId>
<version>5.5.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>5.0.9.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>5.0.9.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
<version>5.0.9.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>5.0.9.RELEASE</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<version>1.4.199</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
</build>
</project>

60
core-java-modules/core-java-jndi/src/test/java/com/baeldung/jndi/JndiUnitTest.java Normal file
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@ -0,0 +1,60 @@
package com.baeldung.jndi;
import org.junit.jupiter.api.BeforeAll;
import org.junit.jupiter.api.Test;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.jndi.JndiTemplate;
import org.springframework.mock.jndi.SimpleNamingContextBuilder;
import javax.naming.*;
import javax.sql.DataSource;
import java.util.Enumeration;
import static org.junit.jupiter.api.Assertions.*;
class JndiUnitTest {
private static InitialContext ctx;
private static DriverManagerDataSource ds;
@BeforeAll
static void setUp() throws Exception {
SimpleNamingContextBuilder builder = new SimpleNamingContextBuilder();
ds = new DriverManagerDataSource("jdbc:h2:mem:mydb");
builder.activate();
JndiTemplate jndiTemplate = new JndiTemplate();
ctx = (InitialContext) jndiTemplate.getContext();
}
@Test
void givenACompositeName_whenAddingAnElement_thenNameIncludesIt() throws Exception {
Name objectName = new CompositeName("java:comp/env/jdbc");
Enumeration<String> elements = objectName.getAll();
while(elements.hasMoreElements()) {
System.out.println(elements.nextElement());
}
objectName.add("example");
assertEquals("env", objectName.get(1));
assertEquals("example", objectName.get(objectName.size() - 1));
}
@Test
void givenADataSource_whenAddingDriver_thenBind() throws Exception {
ds.setDriverClassName("org.h2.Driver");
ctx.bind("java:comp/env/jdbc/datasource", ds);
}
@Test
void givenContext_whenLookupByName_thenValidDataSource() throws Exception {
DataSource ds = (DataSource) ctx.lookup("java:comp/env/jdbc/datasource");
assertNotNull(ds);
assertNotNull(ds.getConnection());
}
}

42
core-java-modules/core-java-jndi/src/test/java/com/baeldung/jndi/exceptions/JndiExceptionsUnitTest.java Normal file
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@ -0,0 +1,42 @@
package com.baeldung.jndi.exceptions;
import org.junit.jupiter.api.MethodOrderer;
import org.junit.jupiter.api.Order;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.TestMethodOrder;
import org.springframework.jndi.JndiTemplate;
import org.springframework.mock.jndi.SimpleNamingContextBuilder;
import javax.naming.InitialContext;
import javax.naming.NameNotFoundException;
import javax.naming.NoInitialContextException;
import static org.junit.jupiter.api.Assertions.assertThrows;
@TestMethodOrder(MethodOrderer.OrderAnnotation.class)
public class JndiExceptionsUnitTest {
@Test
@Order(1)
void givenNoContext_whenLookupObject_thenThrowNoInitialContext() {
assertThrows(NoInitialContextException.class, () -> {
JndiTemplate jndiTemplate = new JndiTemplate();
InitialContext ctx = (InitialContext) jndiTemplate.getContext();
ctx.lookup("java:comp/env/jdbc/datasource");
}).printStackTrace();
}
@Test
@Order(2)
void givenEmptyContext_whenLookupNotBounds_thenThrowNameNotFound() {
assertThrows(NameNotFoundException.class, () -> {
SimpleNamingContextBuilder builder = new SimpleNamingContextBuilder();
builder.activate();
JndiTemplate jndiTemplate = new JndiTemplate();
InitialContext ctx = (InitialContext) jndiTemplate.getContext();
ctx.lookup("badJndiName");
}).printStackTrace();
}
}

2
core-java-modules/core-java-lambdas/pom.xml
View File

@ -5,7 +5,7 @@
<modelVersion>4.0.0</modelVersion>
<artifactId>core-java-lambdas</artifactId>
<version>0.1.0-SNAPSHOT</version>
<name>core-java</name>
<name>core-java-lambdas</name>
<packaging>jar</packaging>
<parent>

13
core-java-modules/core-java-lang-oop-2/pom.xml
View File

@ -14,6 +14,19 @@
<relativePath>../../parent-java</relativePath>
</parent>
<dependencies>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<version>${h2.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
<properties>
<h2.version>1.4.199</h2.version>
</properties>
<build>
<finalName>core-java-lang-oop-2</finalName>
<resources>

31
core-java-modules/core-java-lang-oop-2/src/main/java/com/baeldung/accessmodifiers/publicmodifier/ListOfThree.java Normal file
View File

@ -0,0 +1,31 @@
package com.baeldung.accessmodifiers.publicmodifier;
import java.util.AbstractList;
import java.util.Arrays;
public class ListOfThree<E> extends AbstractList<E> {
private static final int LENGTH = 3;
private Object[] elements;
public ListOfThree(E[] data) {
if(data == null
|| data.length != LENGTH)
throw new IllegalArgumentException();
this.elements = Arrays.copyOf(data, data.length); //shallow copy
}
@Override
@SuppressWarnings("unchecked")
public E get(int index) {
return (E)elements[index];
}
@Override
public int size() {
return LENGTH;
}
}

7
core-java-modules/core-java-lang-oop-2/src/main/java/com/baeldung/accessmodifiers/publicmodifier/SpecialCharacters.java Normal file
View File

@ -0,0 +1,7 @@
package com.baeldung.accessmodifiers.publicmodifier;
public class SpecialCharacters {
public static final String SLASH = "/";
}

67
core-java-modules/core-java-lang-oop-2/src/main/java/com/baeldung/accessmodifiers/publicmodifier/Student.java Normal file
View File

@ -0,0 +1,67 @@
package com.baeldung.accessmodifiers.publicmodifier;
import java.math.BigDecimal;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Date;
public class Student {
private StudentGrade grade; //new data representation
// private int grade; //old data representation
private String name;
private int age;
public void setGrade(int grade) {
this.grade = new StudentGrade(grade);
}
public int getGrade() {
return this.grade.getGrade().intValue(); //int is returned for backward compatibility
}
public Connection getConnection() throws SQLException {
final String URL = "jdbc:h2:~/test";
return DriverManager.getConnection(URL, "sa", "");
}
public void setAge(int age) {
if (age < 0 || age > 150) {
throw new IllegalArgumentException();
}
this.age = age;
}
public int getAge() {
return age;
}
@Override
public String toString() {
return this.name;
}
private class StudentGrade {
private BigDecimal grade = BigDecimal.ZERO;
private Date updatedAt;
public StudentGrade(int grade) {
this.grade = new BigDecimal(grade);
this.updatedAt = new Date();
}
public BigDecimal getGrade() {
return grade;
}
public Date getDate() {
return updatedAt;
}
}
}

59
core-java-modules/core-java-lang-oop-2/src/main/java/com/baeldung/core/modifiers/Employee.java Normal file
View File

@ -0,0 +1,59 @@
package com.baeldung.core.modifiers;
public class Employee {
private String privateId;
private String name;
private boolean manager;
public Employee(String id, String name) {
setPrivateId(id);
setName(name);
}
private Employee(String id, String name, boolean managerAttribute) {
this.privateId = id;
this.name = name;
this.privateId = id + "_ID-MANAGER";
}
public void setPrivateId(String customId) {
if (customId.endsWith("_ID")) {
this.privateId = customId;
} else {
this.privateId = customId + "_ID";
}
}
public String getPrivateId() {
return privateId;
}
public boolean isManager() {
return manager;
}
public void elevateToManager() {
if ("Carl".equals(this.name)) {
setManager(true);
}
}
private void setManager(boolean manager) {
this.manager = manager;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public static Employee buildManager(String id, String name) {
return new Employee(id, name, true);
}
}

10
core-java-modules/core-java-lang-oop-2/src/main/java/com/baeldung/core/modifiers/ExampleClass.java Normal file
View File

@ -0,0 +1,10 @@
package com.baeldung.core.modifiers;
public class ExampleClass {
public static void main(String[] args) {
Employee employee = new Employee("Bob","ABC123");
employee.setPrivateId("BCD234");
System.out.println(employee.getPrivateId());
}
}

16
core-java-modules/core-java-lang-oop-2/src/main/java/com/baeldung/core/modifiers/PublicOuterClass.java Normal file
View File

@ -0,0 +1,16 @@
package com.baeldung.core.modifiers;
public class PublicOuterClass {
public PrivateInnerClass getInnerClassInstance() {
PrivateInnerClass myPrivateClassInstance = this.new PrivateInnerClass();
myPrivateClassInstance.id = "ID1";
myPrivateClassInstance.name = "Bob";
return myPrivateClassInstance;
}
private class PrivateInnerClass {
public String name;
public String id;
}
}

93
core-java-modules/core-java-lang-oop-2/src/test/java/com/baeldung/accessmodifiers/PublicAccessModifierUnitTest.java Normal file
View File

@ -0,0 +1,93 @@
package com.baeldung.accessmodifiers;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.TestInstance;
import org.junit.jupiter.api.TestInstance.Lifecycle;
import com.baeldung.accessmodifiers.publicmodifier.ListOfThree;
import com.baeldung.accessmodifiers.publicmodifier.Student;
import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertTrue;
import static org.junit.jupiter.api.Assertions.assertEquals;
import java.math.BigDecimal;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
@TestInstance(Lifecycle.PER_CLASS)
public class PublicAccessModifierUnitTest {
@Test
public void whenUsingBigDecimalIntValueMethod_correspondingIntIsReturned() {
assertEquals(0, new BigDecimal(0).intValue()); //instance member
}
@Test
public void whenUsingIntegerMaxValueField_maxPossibleIntValueIsReturned() {
assertEquals(2147483647, Integer.MAX_VALUE); //static field
}
@Test
public void whenChangingStudentInternalRepresentation_clientCodeWillNotBreak() {
Student student = new Student();
student.setGrade(100);
assertEquals(100, student.getGrade());
}
@Test
public void whenUsingEntrySet_keyValuePairsAreReturned() {
Map<String, String> mapObject = new HashMap<String, String>();
mapObject.put("name", "Alex");
for(Map.Entry<String, String> entry : mapObject.entrySet()) {
assertEquals("name", entry.getKey());
assertEquals("Alex", entry.getValue());
}
}
@Test
public void whenUsingStringToLowerCase_stringTurnsToLowerCase() {
assertEquals("alex", "ALEX".toLowerCase());
}
@Test
public void whenParsingStringOne_parseIntReturns1() {
assertEquals(1, Integer.parseInt("1"));
}
@Test
public void whenConnectingToH2_connectionInstanceIsReturned() throws SQLException {
final String url = "jdbc:h2:~/test";
Connection conn = DriverManager.getConnection(url, "sa", "");
assertNotNull(conn);
}
@Test
public void whenCreatingCustomList_concreteAndInheritedMethodsWork() {
String[] dataSet1 = new String[] {"zero", "one", "two"};
List<String> list1 = new ListOfThree<String>(dataSet1);
//our implemented methods
assertEquals("one", list1.get(1));
assertEquals(3, list1.size());
//inherited implementations
assertEquals(1, list1.indexOf("one"));
String[] dataSet2 = new String[] {"two", "zero", "one"};
List<String> list2 = new ListOfThree<String>(dataSet2);
assertTrue(list1.containsAll(list2));
}
}

3
core-java-modules/core-java-networking-2/README.md Normal file
View File

@ -0,0 +1,3 @@
### Relevant Articles
- [Checking if a URL Exists in Java](https://www.baeldung.com/java-check-url-exists)

2
core-java-modules/core-java-networking/src/main/java/com/baeldung/http/FullResponseBuilder.java → core-java-modules/core-java-networking/src/main/java/com/baeldung/httprequest/FullResponseBuilder.java
View File

@ -1,4 +1,4 @@
package com.baeldung.http;
package com.baeldung.httprequest;
import java.io.BufferedReader;
import java.io.IOException;

2
core-java-modules/core-java-networking/src/main/java/com/baeldung/http/ParameterStringBuilder.java → core-java-modules/core-java-networking/src/main/java/com/baeldung/httprequest/ParameterStringBuilder.java
View File

@ -1,4 +1,4 @@
package com.baeldung.http;
package com.baeldung.httprequest;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;

5
core-java-modules/core-java-networking/src/test/java/com/baeldung/http/HttpRequestLiveTest.java → core-java-modules/core-java-networking/src/test/java/com/baeldung/httprequest/HttpRequestLiveTest.java
View File

@ -1,8 +1,11 @@
package com.baeldung.http;
package com.baeldung.httprequest;
import org.apache.commons.lang3.StringUtils;
import org.junit.Test;
import com.baeldung.httprequest.FullResponseBuilder;
import com.baeldung.httprequest.ParameterStringBuilder;
import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.IOException;

1
core-java-modules/core-java-optional/pom.xml
View File

@ -3,6 +3,7 @@
<artifactId>core-java-optional</artifactId>
<version>0.1.0-SNAPSHOT</version>
<packaging>jar</packaging>
<name>core-java-optional</name>
<parent>
<groupId>com.baeldung.core-java-modules</groupId>

2
core-java-modules/core-java-os/README.md
View File

@ -7,4 +7,4 @@ This module uses Java 9, so make sure to have the JDK 9 installed to run it.
- [Java 9 Process API Improvements](http://www.baeldung.com/java-9-process-api)
- [Guide to java.lang.Process API](https://www.baeldung.com/java-process-api)
- [Guide to java.lang.ProcessBuilder API](https://www.baeldung.com/java-lang-processbuilder-api)
- [Get the Current Working Directory in Java](https://www.baeldung.com/java-current-directory)

20
core-java-modules/core-java-os/src/main/java/com/baeldung/system/exit/SystemExitExample.java Normal file
View File

@ -0,0 +1,20 @@
package com.baeldung.system.exit;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
public class SystemExitExample {
public void readFile() {
try {
BufferedReader br = new BufferedReader(new FileReader("file.txt"));
System.out.println(br.readLine());
br.close();
} catch (IOException e) {
System.exit(2);
} finally {
System.out.println("Exiting the program");
}
}
}

63
core-java-modules/core-java-os/src/test/java/com/baeldung/system/exit/SystemExitUnitTest.java Normal file
View File

@ -0,0 +1,63 @@
package com.baeldung.system.exit;
import static org.junit.Assert.assertEquals;
import java.security.Permission;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
public class SystemExitUnitTest {
protected static class ExitException extends SecurityException {
private static final long serialVersionUID = 1L;
public final int status;
public ExitException(int status) {
this.status = status;
}
}
private static class NoExitSecurityManager extends SecurityManager {
@Override
public void checkPermission(Permission perm) {
}
@Override
public void checkPermission(Permission perm, Object context) {
}
@Override
public void checkExit(int status) {
super.checkExit(status);
throw new ExitException(status);
}
}
private SecurityManager securityManager;
private SystemExitExample example;
@Before
public void setUp() throws Exception {
example = new SystemExitExample();
securityManager = System.getSecurityManager();
System.setSecurityManager(new NoExitSecurityManager());
}
@After
public void tearDown() throws Exception {
System.setSecurityManager(securityManager);
}
@Test
public void testExit() throws Exception {
try {
example.readFile();
} catch (ExitException e) {
assertEquals("Exit status", 2, e.status);
}
}
}

54
gradle-5/build.gradle Normal file
View File

@ -0,0 +1,54 @@
plugins {
id "application"
}
apply plugin :"java"
description = "Java MainClass execution examples"
group = "com.baeldung"
version = "0.0.1"
sourceCompatibility = "1.8"
targetCompatibility = "1.8"
ext {
javaMainClass = "com.baeldung.gradle.exec.MainClass"
}
jar {
manifest {
attributes(
"Main-Class": javaMainClass
)
}
}
application {
mainClassName = javaMainClass
}
task runWithJavaExec(type: JavaExec) {
group = "Execution"
description = "Run the main class with JavaExecTask"
classpath = sourceSets.main.runtimeClasspath
main = javaMainClass
}
task runWithExec(type: Exec) {
dependsOn build
group = "Execution"
description = "Run the main class with ExecTask"
commandLine "java", "-classpath", sourceSets.main.runtimeClasspath.getAsPath(), javaMainClass
}
task runWithExecJarExecutable(type: Exec) {
dependsOn jar
group = "Execution"
description = "Run the output executable jar with ExecTask"
commandLine "java", "-jar", jar.archiveFile.get()
}
task runWithExecJarOnClassPath(type: Exec) {
dependsOn jar
group = "Execution"
description = "Run the mainClass from the output jar in classpath with ExecTask"
commandLine "java", "-classpath", jar.archiveFile.get() , javaMainClass
}

BIN
gradle-5/gradle/wrapper/gradle-wrapper.jar vendored Normal file
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Binary file not shown.

5
gradle-5/gradle/wrapper/gradle-wrapper.properties vendored Normal file
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@ -0,0 +1,5 @@
distributionBase=GRADLE_USER_HOME
distributionPath=wrapper/dists
zipStoreBase=GRADLE_USER_HOME
zipStorePath=wrapper/dists
distributionUrl=https\://services.gradle.org/distributions/gradle-5.5.1-bin.zip

164
gradle-5/gradlew vendored Executable file
View File

@ -0,0 +1,164 @@
#!/usr/bin/env bash
##############################################################################
##
## Gradle start up script for UN*X
##
##############################################################################
# Attempt to set APP_HOME
# Resolve links: $0 may be a link
PRG="$0"
# Need this for relative symlinks.
while [ -h "$PRG" ] ; do
ls=`ls -ld "$PRG"`
link=`expr "$ls" : '.*-> \(.*\)$'`
if expr "$link" : '/.*' > /dev/null; then
PRG="$link"
else
PRG=`dirname "$PRG"`"/$link"
fi
done
SAVED="`pwd`"
cd "`dirname \"$PRG\"`/" >/dev/null
APP_HOME="`pwd -P`"
cd "$SAVED" >/dev/null
APP_NAME="Gradle"
APP_BASE_NAME=`basename "$0"`
# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
DEFAULT_JVM_OPTS=""
# Use the maximum available, or set MAX_FD != -1 to use that value.
MAX_FD="maximum"
warn ( ) {
echo "$*"
}
die ( ) {
echo
echo "$*"
echo
exit 1
}
# OS specific support (must be 'true' or 'false').
cygwin=false
msys=false
darwin=false
nonstop=false
case "`uname`" in
CYGWIN* )
cygwin=true
;;
Darwin* )
darwin=true
;;
MINGW* )
msys=true
;;
NONSTOP* )
nonstop=true
;;
esac
CLASSPATH=$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" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
MAX_FD_LIMIT=`ulimit -H -n`
if [ $? -eq 0 ] ; then
if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
MAX_FD="$MAX_FD_LIMIT"
fi
ulimit -n $MAX_FD
if [ $? -ne 0 ] ; then
warn "Could not set maximum file descriptor limit: $MAX_FD"
fi
else
warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
fi
fi
# For Darwin, add options to specify how the application appears in the dock
if $darwin; then
GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
fi
# For Cygwin, switch paths to Windows format before running java
if $cygwin ; then
APP_HOME=`cygpath --path --mixed "$APP_HOME"`
CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
JAVACMD=`cygpath --unix "$JAVACMD"`
# We build the pattern for arguments to be converted via cygpath
ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
SEP=""
for dir in $ROOTDIRSRAW ; do
ROOTDIRS="$ROOTDIRS$SEP$dir"
SEP="|"
done
OURCYGPATTERN="(^($ROOTDIRS))"
# Add a user-defined pattern to the cygpath arguments
if [ "$GRADLE_CYGPATTERN" != "" ] ; then
OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
fi
# Now convert the arguments - kludge to limit ourselves to /bin/sh
i=0
for arg in "$@" ; do
CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
CHECK2=`echo "$arg"|egrep -c "^-"` ### Determine if an option
if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then ### Added a condition
eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
else
eval `echo args$i`="\"$arg\""
fi
i=$((i+1))
done
case $i in
(0) set -- ;;
(1) set -- "$args0" ;;
(2) set -- "$args0" "$args1" ;;
(3) set -- "$args0" "$args1" "$args2" ;;
(4) set -- "$args0" "$args1" "$args2" "$args3" ;;
(5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
(6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
(7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
(8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
(9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
esac
fi
# Split up the JVM_OPTS And GRADLE_OPTS values into an array, following the shell quoting and substitution rules
function splitJvmOpts() {
JVM_OPTS=("$@")
}
eval splitJvmOpts $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS
JVM_OPTS[${#JVM_OPTS[*]}]="-Dorg.gradle.appname=$APP_BASE_NAME"
exec "$JAVACMD" "${JVM_OPTS[@]}" -classpath "$CLASSPATH" org.gradle.wrapper.GradleWrapperMain "$@"

90
gradle-5/gradlew.bat vendored Normal file
View File

@ -0,0 +1,90 @@
@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 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=
@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 init
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 init
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
:init
@rem Get command-line arguments, handling Windows variants
if not "%OS%" == "Windows_NT" goto win9xME_args
if "%@eval[2+2]" == "4" goto 4NT_args
:win9xME_args
@rem Slurp the command line arguments.
set CMD_LINE_ARGS=
set _SKIP=2
:win9xME_args_slurp
if "x%~1" == "x" goto execute
set CMD_LINE_ARGS=%*
goto execute
:4NT_args
@rem Get arguments from the 4NT Shell from JP Software
set CMD_LINE_ARGS=%$
: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 %CMD_LINE_ARGS%
: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

8
gradle-5/src/main/java/com/baeldung/gradle/exec/MainClass.java Normal file
View File

@ -0,0 +1,8 @@
package com.baeldung.gradle.exec;
public class MainClass {
public static void main(String[] args) {
System.out.println("Goodbye cruel world ...");
}
}

2
guava-collections/src/test/java/org/baeldung/guava/GuavaMapInitializeUnitTest.java → guava-collections/src/test/java/org/baeldung/guava/maps/initialize/GuavaMapInitializeUnitTest.java
View File

@ -1,4 +1,4 @@
package org.baeldung.guava;
package org.baeldung.guava.maps.initialize;
import static org.hamcrest.core.IsEqual.equalTo;
import static org.junit.Assert.*;

4
httpclient-simple/pom.xml
View File

@ -21,12 +21,12 @@
<dependency>
<groupId>org.springframework.security</groupId>
<artifactId>spring-security-web</artifactId>
<version>${spring.version}</version>
<version>${spring-security.version}</version>
</dependency>
<dependency>
<groupId>org.springframework.security</groupId>
<artifactId>spring-security-config</artifactId>
<version>${spring.version}</version>
<version>${spring-security.version}</version>
</dependency>
<!-- Spring -->

1
jackson-2/README.md
View File

@ -11,3 +11,4 @@ The "REST With Spring" Classes: http://bit.ly/restwithspring
- [Working with Tree Model Nodes in Jackson](https://www.baeldung.com/jackson-json-node-tree-model)
- [Converting JSON to CSV in Java](https://www.baeldung.com/java-converting-json-to-csv)
- [Compare Two JSON Objects with Jackson](https://www.baeldung.com/jackson-compare-two-json-objects)
- [Calling Default Serializer from Custom Serializer in Jackson](https://www.baeldung.com/jackson-call-default-serializer-from-custom-serializer)

26
java-blockchain/.gitignore vendored Normal file
View File

@ -0,0 +1,26 @@
*.class
0.*
#folders#
/target
/neoDb*
/data
/src/main/webapp/WEB-INF/classes
*/META-INF/*
.resourceCache
# Packaged files #
*.jar
*.war
*.ear
# Files generated by integration tests
*.txt
backup-pom.xml
/bin/
/temp
#IntelliJ specific
.idea/
*.iml

6
java-blockchain/README.md Normal file
View File

@ -0,0 +1,6 @@
=========
## Basic Implementation of Blockchian in Java
### Relevant Articles:
- []()

40
java-blockchain/pom.xml Normal file
View File

@ -0,0 +1,40 @@
<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>
<groupId>com.baeldung.blockchain</groupId>
<artifactId>java-blockchain</artifactId>
<version>0.1.0-SNAPSHOT</version>
<name>java-blockchain</name>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung</groupId>
<artifactId>parent-java</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../parent-java</relativePath>
</parent>
<build>
<finalName>java-blockchain</finalName>
<resources>
<resource>
<directory>src/main/resources</directory>
<filtering>true</filtering>
</resource>
</resources>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>${maven-compiler-plugin.version}</version>
<configuration>
<source>${maven.compiler.source}</source>
<target>${maven.compiler.target}</target>
</configuration>
</plugin>
</plugins>
</build>
<properties>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
</properties>
</project>

65
java-blockchain/src/main/java/com/baeldung/blockchain/Block.java Normal file
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package com.baeldung.blockchain;
import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Date;
import java.util.logging.Level;
import java.util.logging.Logger;
public class Block {
private static Logger logger = Logger.getLogger(Block.class.getName());
private String hash;
private String previousHash;
private String data;
private long timeStamp;
private int nonce;
public Block(String data, String previousHash) {
this.data = data;
this.previousHash = previousHash;
this.timeStamp = new Date().getTime();
this.hash = calculateBlockHash();
}
public String mineBlock(int prefix) {
String prefixString = new String(new char[prefix]).replace('\0', '0');
while (!hash.substring(0, prefix)
.equals(prefixString)) {
nonce++;
hash = calculateBlockHash();
}
return hash;
}
public String calculateBlockHash() {
String dataToHash = previousHash + Long.toString(timeStamp) + Integer.toString(nonce) + data;
MessageDigest digest = null;
byte[] bytes = null;
try {
digest = MessageDigest.getInstance("SHA-256");
bytes = digest.digest(dataToHash.getBytes("UTF-8"));
} catch (NoSuchAlgorithmException | UnsupportedEncodingException ex) {
logger.log(Level.SEVERE, ex.getMessage());
}
StringBuffer buffer = new StringBuffer();
for (byte b : bytes) {
buffer.append(String.format("%02x", b));
}
return buffer.toString();
}
public String getHash() {
return this.hash;
}
public String getPreviousHash() {
return this.previousHash;
}
public void setData(String data) {
this.data = data;
}
}

0
spring-security-mvc-boot/spring-security-mvc-boot-default/src/main/resources/logback.xml → java-blockchain/src/main/resources/logback.xml
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67
java-blockchain/src/test/java/com/baeldung/blockchain/BlockchainUnitTest.java Normal file
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package com.baeldung.blockchain;
import static org.junit.jupiter.api.Assertions.assertTrue;
import java.util.ArrayList;
import java.util.List;
import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;
public class BlockchainUnitTest {
public static List<Block> blockchain = new ArrayList<Block>();
public static int prefix = 4;
public static String prefixString = new String(new char[prefix]).replace('\0', '0');
@BeforeClass
public static void setUp() {
Block genesisBlock = new Block("The is the Genesis Block.", "0");
genesisBlock.mineBlock(prefix);
blockchain.add(genesisBlock);
Block firstBlock = new Block("The is the First Block.", genesisBlock.getHash());
firstBlock.mineBlock(prefix);
blockchain.add(firstBlock);
}
@Test
public void givenBlockchain_whenNewBlockAdded_thenSuccess() {
Block newBlock = new Block("The is a New Block.", blockchain.get(blockchain.size() - 1)
.getHash());
newBlock.mineBlock(prefix);
assertTrue(newBlock.getHash()
.substring(0, prefix)
.equals(prefixString));
blockchain.add(newBlock);
}
@Test
public void givenBlockchain_whenValidated_thenSuccess() {
boolean flag = true;
for (int i = 0; i < blockchain.size(); i++) {
String previousHash = i == 0 ? "0"
: blockchain.get(i - 1)
.getHash();
flag = blockchain.get(i)
.getHash()
.equals(blockchain.get(i)
.calculateBlockHash())
&& previousHash.equals(blockchain.get(i)
.getPreviousHash())
&& blockchain.get(i)
.getHash()
.substring(0, prefix)
.equals(prefixString);
if (!flag)
break;
}
assertTrue(flag);
}
@AfterClass
public static void tearDown() {
blockchain.clear();
}
}

13
java-blockchain/src/test/resources/.gitignore vendored Normal file
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*.class
#folders#
/target
/neoDb*
/data
/src/main/webapp/WEB-INF/classes
*/META-INF/*
# Packaged files #
*.jar
*.war
*.ear

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