core-java-lambdas 项目添加

Author: honeymoose

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

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+## Relevant articles:
+
+- [Why Do Local Variables Used in Lambdas Have to Be Final or Effectively Final?](https://www.baeldung.com/java-lambda-effectively-final-local-variables)
+- [Java 8 – Powerful Comparison with Lambdas](http://www.baeldung.com/java-8-sort-lambda)
+- [Functional Interfaces in Java 8](http://www.baeldung.com/java-8-functional-interfaces)
+- [Lambda Expressions and Functional Interfaces: Tips and Best Practices](http://www.baeldung.com/java-8-lambda-expressions-tips)
+- [Exceptions in Java 8 Lambda Expressions](http://www.baeldung.com/java-lambda-exceptions)
+- [Method References in Java](https://www.baeldung.com/java-method-references)
+- [The Double Colon Operator in Java 8](https://www.baeldung.com/java-8-double-colon-operator)
+- [Serialize a Lambda in Java](https://www.baeldung.com/java-serialize-lambda)
+- [Convert Anonymous Class into Lambda in Java](https://www.baeldung.com/java-from-anonymous-class-to-lambda)
+- [When to Use Callable and Supplier in Java](https://www.baeldung.com/java-callable-vs-supplier)

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

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>core-java-lambdas</artifactId>
+    <packaging>jar</packaging>
+    <name>core-java-lambdas</name>
+
+    <parent>
+        <groupId>com.ossez.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
+        <version>0.0.2-SNAPSHOT</version>
+        <relativePath>../pom.xml</relativePath>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
+    </dependencies>
+
+</project>

core-java-modules/core-java-lambdas/src/main/java/com/baeldung/doublecolon/Computer.java

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+package com.baeldung.doublecolon;
+
+public class Computer {
+
+    private Integer age;
+    private String color;
+    private Integer healty;
+
+    Computer(final int age, final String color) {
+        this.age = age;
+        this.color = color;
+    }
+
+    Computer(final Integer age, final String color, final Integer healty) {
+        this.age = age;
+        this.color = color;
+        this.healty = healty;
+    }
+
+    public Computer() {
+    }
+
+    public Integer getAge() {
+        return age;
+    }
+
+    public void setAge(final Integer age) {
+        this.age = age;
+    }
+
+    String getColor() {
+        return color;
+    }
+
+    public void setColor(final String color) {
+        this.color = color;
+    }
+
+    Integer getHealty() {
+        return healty;
+    }
+
+    void setHealty(final Integer healty) {
+        this.healty = healty;
+    }
+
+    public void turnOnPc() {
+        System.out.println("Computer turned on");
+    }
+
+    public void turnOffPc() {
+        System.out.println("Computer turned off");
+    }
+
+    public Double calculateValue(Double initialValue) {
+        return initialValue / 1.50;
+    }
+
+    @Override
+    public String toString() {
+        return "Computer{" + "age=" + age + ", color='" + color + '\'' + ", healty=" + healty + '}';
+    }
+
+    @Override
+    public boolean equals(final Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+
+        final Computer computer = (Computer) o;
+
+        return (age != null ? age.equals(computer.age) : computer.age == null) && (color != null ? color.equals(computer.color) : computer.color == null);
+
+    }
+
+    @Override
+    public int hashCode() {
+        int result = age != null ? age.hashCode() : 0;
+        result = 31 * result + (color != null ? color.hashCode() : 0);
+        return result;
+    }
+}

core-java-modules/core-java-lambdas/src/main/java/com/baeldung/doublecolon/ComputerUtils.java

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+package com.baeldung.doublecolon;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import com.baeldung.doublecolon.function.ComputerPredicate;
+
+public class ComputerUtils {
+
+    static final ComputerPredicate after2010Predicate = (c) -> (c.getAge() > 2010);
+    static final ComputerPredicate blackPredicate = (c) -> "black".equals(c.getColor());
+
+    public static List<Computer> filter(final List<Computer> inventory, final ComputerPredicate p) {
+
+        final List<Computer> result = new ArrayList<>();
+        inventory.stream().filter(p::filter).forEach(result::add);
+
+        return result;
+    }
+
+    static void repair(final Computer computer) {
+        if (computer.getHealty() < 50) {
+            computer.setHealty(100);
+        }
+    }
+
+}

core-java-modules/core-java-lambdas/src/main/java/com/baeldung/doublecolon/MacbookPro.java

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+package com.baeldung.doublecolon;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.function.Function;
+
+public class MacbookPro extends Computer {
+
+    private static final Logger LOG = LoggerFactory.getLogger(MacbookPro.class);
+
+    public MacbookPro(int age, String color) {
+        super(age, color);
+    }
+
+    MacbookPro(Integer age, String color, Integer healty) {
+        super(age, color, healty);
+    }
+
+    @Override
+    public void turnOnPc() {
+        LOG.debug("MacbookPro turned on");
+    }
+
+    @Override
+    public void turnOffPc() {
+        LOG.debug("MacbookPro turned off");
+    }
+
+    @Override
+    public Double calculateValue(Double initialValue) {
+
+        Function<Double, Double> function = super::calculateValue;
+        final Double pcValue = function.apply(initialValue);
+        LOG.debug("First value is:" + pcValue);
+        return pcValue + (initialValue / 10);
+
+    }
+}

core-java-modules/core-java-lambdas/src/main/java/com/baeldung/doublecolon/function/ComputerPredicate.java

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+package com.baeldung.doublecolon.function;
+
+import com.baeldung.doublecolon.Computer;
+
+@FunctionalInterface
+public interface ComputerPredicate {
+
+    boolean filter(Computer c);
+
+}

core-java-modules/core-java-lambdas/src/main/java/com/baeldung/doublecolon/function/TriFunction.java

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+package com.baeldung.doublecolon.function;
+
+import java.util.Objects;
+import java.util.function.Function;
+
+@FunctionalInterface
+public interface TriFunction<A, B, C, R> {
+
+    R apply(A a, B b, C c);
+
+    default <V> TriFunction<A, B, C, V> andThen(final Function<? super R, ? extends V> after) {
+        Objects.requireNonNull(after);
+        return (final A a, final B b, final C c) -> after.apply(apply(a, b, c));
+    }
+}

core-java-modules/core-java-lambdas/src/main/java/com/baeldung/java8/entity/Human.java

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+package com.baeldung.java8.entity;
+
+public class Human {
+    private String name;
+    private int age;
+
+    public Human() {
+        super();
+    }
+
+    public Human(final String name, final int age) {
+        super();
+
+        this.name = name;
+        this.age = age;
+    }
+
+    // API
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(final String name) {
+        this.name = name;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public void setAge(final int age) {
+        this.age = age;
+    }
+
+    // compare
+
+    public static int compareByNameThenAge(final Human lhs, final Human rhs) {
+        if (lhs.name.equals(rhs.name)) {
+            return Integer.compare(lhs.age, rhs.age);
+        } else {
+            return lhs.name.compareTo(rhs.name);
+        }
+    }
+
+    //
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + age;
+        result = prime * result + ((name == null) ? 0 : name.hashCode());
+        return result;
+    }
+
+    @Override
+    public boolean equals(final Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        final Human other = (Human) obj;
+        if (age != other.age) {
+            return false;
+        }
+        if (name == null) {
+            if (other.name != null) {
+                return false;
+            }
+        } else if (!name.equals(other.name)) {
+            return false;
+        }
+        return true;
+    }
+
+    @Override
+    public String toString() {
+        final StringBuilder builder = new StringBuilder();
+        builder.append("Human [name=").append(name).append(", age=").append(age).append("]");
+        return builder.toString();
+    }
+
+}

core-java-modules/core-java-lambdas/src/main/java/com/baeldung/java8/lambda/exceptions/LambdaExceptionWrappers.java

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+package com.baeldung.java8.lambda.exceptions;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.function.Consumer;
+
+public class LambdaExceptionWrappers {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(LambdaExceptionWrappers.class);
+
+    public static Consumer<Integer> lambdaWrapper(Consumer<Integer> consumer) {
+        return i -> {
+            try {
+                consumer.accept(i);
+            } catch (ArithmeticException e) {
+                LOGGER.error("Arithmetic Exception occurred.", e);
+            }
+        };
+    }
+
+    static <T, E extends Exception> Consumer<T> consumerWrapper(Consumer<T> consumer, Class<E> clazz) {
+        return i -> {
+            try {
+                consumer.accept(i);
+            } catch (Exception ex) {
+                try {
+                    E exCast = clazz.cast(ex);
+                    LOGGER.error("Exception occurred.", exCast);
+                } catch (ClassCastException ccEx) {
+                    throw ex;
+                }
+            }
+        };
+    }
+
+    public static <T> Consumer<T> throwingConsumerWrapper(ThrowingConsumer<T, Exception> throwingConsumer) {
+        return i -> {
+            try {
+                throwingConsumer.accept(i);
+            } catch (Exception ex) {
+                throw new RuntimeException(ex);
+            }
+        };
+    }
+
+    public static <T, E extends Exception> Consumer<T> handlingConsumerWrapper(ThrowingConsumer<T, E> throwingConsumer, Class<E> exceptionClass) {
+        return i -> {
+            try {
+                throwingConsumer.accept(i);
+            } catch (Exception ex) {
+                try {
+                    E exCast = exceptionClass.cast(ex);
+                    LOGGER.error("Exception occurred.", exCast);
+                } catch (ClassCastException ccEx) {
+                    throw new RuntimeException(ex);
+                }
+            }
+        };
+    }
+
+}

core-java-modules/core-java-lambdas/src/main/java/com/baeldung/java8/lambda/exceptions/ThrowingConsumer.java

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+package com.baeldung.java8.lambda.exceptions;
+
+@FunctionalInterface
+public interface ThrowingConsumer<T, E extends Exception> {
+
+    void accept(T t) throws E;
+
+}