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

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This commit is contained in:
panos-kakos
2023-10-13 14:41:35 +03:00
committed by GitHub
parent ff826f0d08
commit ee98df03f4
38 changed files with 200 additions and 76 deletions
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core-java-modules/core-java-streams-2/src/main/java/com/baeldung/reduce/application/Application.java
-39
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@@ -1,39 +0,0 @@
package com.baeldung.reduce.application;
import com.baeldung.reduce.entities.User;
import com.baeldung.reduce.utilities.NumberUtils;
import java.util.ArrayList;
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);
}
}
core-java-modules/core-java-streams-2/src/main/java/com/baeldung/reduce/benchmarks/JMHStreamReduceBenchMark.java
-52
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package com.baeldung.reduce.benchmarks;
import com.baeldung.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);
}
}
core-java-modules/core-java-streams-2/src/main/java/com/baeldung/reduce/entities/Rating.java
-39
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package com.baeldung.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;
}
}
core-java-modules/core-java-streams-2/src/main/java/com/baeldung/reduce/entities/Review.java
-28
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@@ -1,28 +0,0 @@
package com.baeldung.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;
}
}
core-java-modules/core-java-streams-2/src/main/java/com/baeldung/reduce/entities/User.java
-25
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package com.baeldung.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 + '}';
}
}
core-java-modules/core-java-streams-2/src/main/java/com/baeldung/reduce/utilities/NumberUtils.java
-52
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package com.baeldung.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;
}
}