[JAVA-12051] Moved code to core-java-streams-simple for ebook (#14889)

2023-10-13 14:41:35 +03:00
parent ff826f0d08
commit ee98df03f4
38 changed files with 200 additions and 76 deletions
@@ -0,0 +1,56 @@
+package com.baeldung.streams.filter;
+
+import java.io.IOException;
+import java.net.HttpURLConnection;
+import java.net.URL;
+
+import javax.net.ssl.HttpsURLConnection;
+
+public class Customer {
+    private String name;
+    private int points;
+    private String profilePhotoUrl;
+
+    public Customer(String name, int points) {
+        this(name, points, "");
+    }
+
+    public Customer(String name, int points, String profilePhotoUrl) {
+        this.name = name;
+        this.points = points;
+        this.profilePhotoUrl = profilePhotoUrl;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public int getPoints() {
+        return points;
+    }
+
+    public boolean hasOver(int points) {
+        return this.points > points;
+    }
+
+    public boolean hasOverHundredPoints() {
+        return this.points > 100;
+    }
+
+    public boolean hasValidProfilePhoto() throws IOException {
+        URL url = new URL(this.profilePhotoUrl);
+        HttpsURLConnection connection = (HttpsURLConnection) url.openConnection();
+        return connection.getResponseCode() == HttpURLConnection.HTTP_OK;
+    }
+
+    public boolean hasValidProfilePhotoWithoutCheckedException() {
+        try {
+            URL url = new URL(this.profilePhotoUrl);
+            HttpsURLConnection connection = (HttpsURLConnection) url.openConnection();
+            return connection.getResponseCode() == HttpURLConnection.HTTP_OK;
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+}
@@ -0,0 +1,43 @@
+package com.baeldung.streams.groupingby;
+
+import java.util.IntSummaryStatistics;
+
+
+public class BlogPost {
+
+    private String title;
+    private String author;
+    private BlogPostType type;
+    private int likes;
+    record AuthPostTypesLikes(String author, BlogPostType type, int likes) {};
+    record PostCountTitlesLikesStats(long postCount, String titles, IntSummaryStatistics likesStats){};
+    record TitlesBoundedSumOfLikes(String titles, int boundedSumOfLikes) {};
+
+    public BlogPost(String title, String author, BlogPostType type, int likes) {
+        this.title = title;
+        this.author = author;
+        this.type = type;
+        this.likes = likes;
+    }
+
+    public String getTitle() {
+        return title;
+    }
+
+    public String getAuthor() {
+        return author;
+    }
+
+    public BlogPostType getType() {
+        return type;
+    }
+
+    public int getLikes() {
+        return likes;
+    }
+
+    @Override
+    public String toString() {
+        return "BlogPost{" + "title='" + title + '\'' + ", type=" + type + ", likes=" + likes + '}';
+    }
+}
@@ -0,0 +1,5 @@
+package com.baeldung.streams.groupingby;
+
+public enum BlogPostType {
+    NEWS, REVIEW, GUIDE
+}
@@ -0,0 +1,41 @@
+package com.baeldung.streams.groupingby;
+
+import java.util.Objects;
+
+public class Tuple {
+    private final BlogPostType type;
+    private final String author;
+
+    public Tuple(BlogPostType type, String author) {
+        this.type = type;
+        this.author = author;
+    }
+
+    public BlogPostType getType() {
+        return type;
+    }
+
+    public String getAuthor() {
+        return author;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o)
+            return true;
+        if (o == null || getClass() != o.getClass())
+            return false;
+        Tuple tuple = (Tuple) o;
+        return type == tuple.type && author.equals(tuple.author);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(type, author);
+    }
+
+    @Override
+    public String toString() {
+        return "Tuple{" + "type=" + type + ", author='" + author + '\'' + '}';
+    }
+}
@@ -0,0 +1,9 @@
+package com.baeldung.streams.parallel;
+
+public class BenchmarkRunner {
+
+    public static void main(String[] args) throws Exception {
+        org.openjdk.jmh.Main.main(args);
+    }
+
+}
@@ -0,0 +1,54 @@
+package com.baeldung.streams.parallel;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.IntStream;
+
+public class DifferentSourceSplitting {
+
+    private static final List<Integer> arrayListOfNumbers = new ArrayList<>();
+    private static final List<Integer> linkedListOfNumbers = new LinkedList<>();
+
+    static {
+        IntStream.rangeClosed(1, 1_000_000).forEach(i -> {
+            arrayListOfNumbers.add(i);
+            linkedListOfNumbers.add(i);
+        });
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void differentSourceArrayListSequential() {
+        arrayListOfNumbers.stream().reduce(0, Integer::sum);
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void differentSourceArrayListParallel() {
+        arrayListOfNumbers.parallelStream().reduce(0, Integer::sum);
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void differentSourceLinkedListSequential() {
+        linkedListOfNumbers.stream().reduce(0, Integer::sum);
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void differentSourceLinkedListParallel() {
+        linkedListOfNumbers.parallelStream().reduce(0, Integer::sum);
+    }
+
+}
@@ -0,0 +1,60 @@
+package com.baeldung.streams.parallel;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.Collectors;
+
+import org.apache.commons.io.FileUtils;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Level;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.TearDown;
+
+@State(Scope.Benchmark)
+public class FileSearchCost {
+
+	private final static String FILE_NAME = "src/main/resources/Test";
+
+	@Setup(Level.Trial)
+	public void setup() throws IOException {
+		for (int i = 0; i < 1500; i++) {
+			File targetFile = new File(FILE_NAME + i);
+			FileUtils.writeStringToFile(targetFile, "Test", "UTF8");
+		}
+	}
+
+	@TearDown(Level.Trial)
+	public void tearDown() {
+		for (int i = 0; i < 1500; i++) {
+			File fileToDelete = new File(FILE_NAME + i);
+			fileToDelete.delete();
+		}
+	}
+
+	@Benchmark
+	@BenchmarkMode(Mode.AverageTime)
+	@OutputTimeUnit(TimeUnit.NANOSECONDS)
+	public static void textFileSearchSequential() throws IOException {
+		Files.walk(Paths.get("src/main/resources/")).map(Path::normalize).filter(Files::isRegularFile)
+				.filter(path -> path.getFileName().toString().endsWith(".txt")).collect(Collectors.toList());
+	}
+
+	@Benchmark
+	@BenchmarkMode(Mode.AverageTime)
+	@OutputTimeUnit(TimeUnit.NANOSECONDS)
+	public static void textFileSearchParallel() throws IOException {
+		Files.walk(Paths.get("src/main/resources/")).parallel().map(Path::normalize).filter(Files::isRegularFile)
+				.filter(path -> path.getFileName().toString().endsWith(".txt")).collect(Collectors.toList());
+	}
+
+}
+
@@ -0,0 +1,52 @@
+package com.baeldung.streams.parallel;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+
+import java.util.Arrays;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.IntStream;
+
+public class MemoryLocalityCosts {
+
+    private static final int[] intArray = new int[1_000_000];
+    private static final Integer[] integerArray = new Integer[1_000_000];
+
+    static {
+        IntStream.rangeClosed(1, 1_000_000).forEach(i -> {
+            intArray[i-1] = i;
+            integerArray[i-1] = i;
+        });
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void localityIntArraySequential() {
+        Arrays.stream(intArray).reduce(0, Integer::sum);
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void localityIntArrayParallel() {
+        Arrays.stream(intArray).parallel().reduce(0, Integer::sum);
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void localityIntegerArraySequential() {
+        Arrays.stream(integerArray).reduce(0, Integer::sum);
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void localityIntegerArrayParallel() {
+        Arrays.stream(integerArray).parallel().reduce(0, Integer::sum);
+    }
+
+}
@@ -0,0 +1,52 @@
+package com.baeldung.streams.parallel;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+public class MergingCosts {
+
+    private static final List<Integer> arrayListOfNumbers = new ArrayList<>();
+
+    static {
+        IntStream.rangeClosed(1, 1_000_000).forEach(i -> {
+            arrayListOfNumbers.add(i);
+        });
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void mergingCostsSumSequential() {
+        arrayListOfNumbers.stream().reduce(0, Integer::sum);
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void mergingCostsSumParallel() {
+        arrayListOfNumbers.stream().parallel().reduce(0, Integer::sum);
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void mergingCostsGroupingSequential() {
+        arrayListOfNumbers.stream().collect(Collectors.toSet());
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void mergingCostsGroupingParallel() {
+        arrayListOfNumbers.stream().parallel().collect(Collectors.toSet());
+    }
+
+}
@@ -0,0 +1,15 @@
+package com.baeldung.streams.parallel;
+
+import java.util.Arrays;
+import java.util.List;
+
+public class ParallelStream {
+
+    public static void main(String[] args) {
+        List<Integer> listOfNumbers = Arrays.asList(1, 2, 3, 4);
+        listOfNumbers.parallelStream().forEach(number ->
+          System.out.println(number + " " + Thread.currentThread().getName())
+        );
+    }
+
+}
@@ -0,0 +1,15 @@
+package com.baeldung.streams.parallel;
+
+import java.util.Arrays;
+import java.util.List;
+
+public class SequentialStream {
+
+    public static void main(String[] args) {
+        List<Integer> listOfNumbers = Arrays.asList(1, 2, 3, 4);
+        listOfNumbers.stream().forEach(number ->
+          System.out.println(number + " " + Thread.currentThread().getName())
+        );
+    }
+
+}
@@ -0,0 +1,27 @@
+package com.baeldung.streams.parallel;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+
+import java.util.concurrent.TimeUnit;
+import java.util.stream.IntStream;
+
+public class SplittingCosts {
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void sourceSplittingIntStreamSequential() {
+        IntStream.rangeClosed(1, 100).reduce(0, Integer::sum);
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void sourceSplittingIntStreamParallel() {
+        IntStream.rangeClosed(1, 100).parallel().reduce(0, Integer::sum);
+    }
+
+}
@@ -0,0 +1,38 @@
+package com.baeldung.streams.reduce.application;
+
+import com.baeldung.streams.reduce.entities.User;
+
+import java.util.Arrays;
+import java.util.List;
+
+public class Application {
+
+    public static void main(String[] args) {
+        List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6);
+        int result1 = numbers.stream().reduce(0, (subtotal, element) -> subtotal + element);
+        System.out.println(result1);
+        
+        int result2 = numbers.stream().reduce(0, Integer::sum);
+        System.out.println(result2);
+
+        List<String> letters = Arrays.asList("a", "b", "c", "d", "e");
+        String result3 = letters.stream().reduce("", (partialString, element) -> partialString + element);
+        System.out.println(result3);
+        
+        String result4 = letters.stream().reduce("", String::concat);
+        System.out.println(result4);
+
+        String result5 = letters.stream().reduce("", (partialString, element) -> partialString.toUpperCase() + element.toUpperCase());
+        System.out.println(result5);
+        
+        List<User> users = Arrays.asList(new User("John", 30), new User("Julie", 35));
+        int result6 = users.stream().reduce(0, (partialAgeResult, user) -> partialAgeResult + user.getAge(), Integer::sum);
+        System.out.println(result6);
+        
+        String result7 = letters.parallelStream().reduce("", String::concat);
+        System.out.println(result7);
+        
+        int result8 = users.parallelStream().reduce(0, (partialAgeResult, user) -> partialAgeResult + user.getAge(), Integer::sum);
+        System.out.println(result8);
+    }    
+}
@@ -0,0 +1,52 @@
+package com.baeldung.streams.reduce.benchmarks;
+
+import com.baeldung.streams.reduce.entities.User;
+import java.util.ArrayList;
+import java.util.List;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.runner.Runner;
+import org.openjdk.jmh.runner.RunnerException;
+import org.openjdk.jmh.runner.options.Options;
+import org.openjdk.jmh.runner.options.OptionsBuilder;
+
+@State(Scope.Thread)
+@BenchmarkMode(Mode.AverageTime)
+public class JMHStreamReduceBenchMark {
+    
+    private final List<User> userList = createUsers();
+
+    public static void main(String[] args) throws RunnerException {
+        
+        Options options = new OptionsBuilder()
+                .include(JMHStreamReduceBenchMark.class.getSimpleName()).threads(1)
+                .forks(1).shouldFailOnError(true).shouldDoGC(true)
+                .jvmArgs("-server").build();
+        new Runner(options).run();
+    }
+    
+    private List<User> createUsers() {
+        List<User> users = new ArrayList<>();
+        for (int i = 0; i <= 1000000; i++) {
+            users.add(new User("John" + i, i));
+        }
+        return users;
+    }
+
+    @Benchmark
+    public Integer executeReduceOnParallelizedStream() {
+        return this.userList
+                .parallelStream()
+                .reduce(0, (partialAgeResult, user) -> partialAgeResult + user.getAge(), Integer::sum);
+    }
+
+    @Benchmark
+    public Integer executeReduceOnSequentialStream() {
+        return this.userList
+                .stream()
+                .reduce(0, (partialAgeResult, user) -> partialAgeResult + user.getAge(), Integer::sum);
+    }
+}
@@ -0,0 +1,39 @@
+package com.baeldung.streams.reduce.entities;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Rating {
+
+    double points;
+    List<Review> reviews = new ArrayList<>();
+
+    public Rating() {}
+
+    public void add(Review review) {
+        reviews.add(review);
+        computeRating();
+    }
+
+    private double computeRating() {
+        double totalPoints = reviews.stream().map(Review::getPoints).reduce(0, Integer::sum);
+        this.points = totalPoints / reviews.size();
+        return this.points;
+    }
+
+    public static Rating average(Rating r1, Rating r2) {
+        Rating combined = new Rating();
+        combined.reviews = new ArrayList<>(r1.reviews);
+        combined.reviews.addAll(r2.reviews);
+        combined.computeRating();
+        return combined;
+    }
+
+    public double getPoints() {
+        return points;
+    }
+
+    public List<Review> getReviews() {
+        return reviews;
+    }
+}
@@ -0,0 +1,28 @@
+package com.baeldung.streams.reduce.entities;
+
+public class Review {
+
+    int points;
+    String review;
+
+    public Review(int points, String review) {
+        this.points = points;
+        this.review = review;
+    }
+
+    public int getPoints() {
+        return points;
+    }
+
+    public void setPoints(int points) {
+        this.points = points;
+    }
+
+    public String getReview() {
+        return review;
+    }
+
+    public void setReview(String review) {
+        this.review = review;
+    }
+}
@@ -0,0 +1,25 @@
+package com.baeldung.streams.reduce.entities;
+
+public class User {
+
+    private final String name;
+    private final int age;
+
+    public User(String name, int age) {
+        this.name = name;
+        this.age = age;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public int getAge() {
+        return age;
+    }
+    
+    @Override
+    public String toString() {
+        return "User{" + "name=" + name + ", age=" + age + '}';
+    }
+}
@@ -0,0 +1,52 @@
+package com.baeldung.streams.reduce.utilities;
+
+import java.util.List;
+import java.util.function.BiFunction;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+public abstract class NumberUtils {
+
+    private static final Logger LOGGER = Logger.getLogger(NumberUtils.class.getName());
+
+    public static int divideListElements(List<Integer> values, Integer divider) {
+        return values.stream()
+                .reduce(0, (a, b) -> {
+                    try {
+                        return a / divider + b / divider;
+                    } catch (ArithmeticException e) {
+                        LOGGER.log(Level.INFO, "Arithmetic Exception: Division by Zero");
+                    }
+                    return 0;
+                });
+    }
+    
+    public static int divideListElementsWithExtractedTryCatchBlock(List<Integer> values, int divider) {
+        return values.stream().reduce(0, (a, b) -> divide(a, divider) + divide(b, divider));
+    }
+    
+    public static int divideListElementsWithApplyFunctionMethod(List<Integer> values, int divider) {
+        BiFunction<Integer, Integer, Integer> division = (a, b) -> a / b;
+        return values.stream().reduce(0, (a, b) -> applyFunction(division, a, divider) + applyFunction(division, b, divider));
+    }
+    
+    private static int divide(int value, int factor) {
+        int result = 0;
+        try {
+            result = value / factor;
+        } catch (ArithmeticException e) {
+            LOGGER.log(Level.INFO, "Arithmetic Exception: Division by Zero");
+        }
+        return result;
+    }
+    
+    private static int applyFunction(BiFunction<Integer, Integer, Integer> function, int a, int b) {
+        try {
+            return function.apply(a, b);
+        }
+        catch(Exception e) {
+            LOGGER.log(Level.INFO, "Exception thrown!");
+        }
+        return 0;
+    }
+}
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>