Lambda表达式练习

练习一

匿名内部类创建线程：

public static void main(String[] args) {
    new Thread(new Runnable() {
        @Override
        public void run() {
            System.out.println("线程中run方法");
        }
    }).start();
}

lambda表达式：

public static void main(String[] args) {
    new Thread(() -> {
            System.out.println("线程中run方法");
        }
    ).start();
}

练习二

public static void main(String[] args) {
    int res = calculateNum(new IntBinaryOperator() {
        @Override
        public int applyAsInt(int left, int right) {
            return left + right;
        }
    });
    System.out.println(res);
}

public static int calculateNum(IntBinaryOperator operator){
    int a = 10;
    int b = 20;

    return operator.applyAsInt(a, b);
}

使用lambda表达式：

public static void main(String[] args) {
    int res = calculateNum((int left, int right) -> {
        return left + right;
    });
    System.out.println(res);
}

public static int calculateNum(IntBinaryOperator operator){
    int a = 10;
    int b = 20;

    return operator.applyAsInt(a, b);
}

练习三

public static void main(String[] args) {
    printNum(new IntPredicate() {
        @Override
        public boolean test(int value) {
            return value % 2 == 0;
        }
    });
}

public static void printNum(IntPredicate predicate){
    int[] arr = {1,2,3,4,5,6,7,8,9,10};
    for (int i : arr) {
        if (predicate.test(i)){
            System.out.println(i);
        }
    }
}

结果：

2
4
6
8
10

Process finished with exit code 0

使用lambda表达式

public static void main(String[] args) {
    printNum((int value) -> {
            return value % 2 == 0;
        }
    );
}

public static void printNum(IntPredicate predicate){
    int[] arr = {1,2,3,4,5,6,7,8,9,10};
    for (int i : arr) {
        if (predicate.test(i)){
            System.out.println(i);
        }
    }
}

练习四

public static void main(String[] args) {
    Integer integer = typeCover(new Function<String, Integer>() {
        @Override
        public Integer apply(String s) {
            return Integer.parseInt(s);
        }
    });
    System.out.println(integer);
}

public static <R> R typeCover(Function<String, R> function){
    String str = "12345";
    return function.apply(str);
}

使用lambda表达式：

public static void main(String[] args) {
    Integer integer = typeCover((String s) -> {
            return Integer.parseInt(s);
        }
    );
    System.out.println(integer);
}

public static <R> R typeCover(Function<String, R> function){
    String str = "12345";
    return function.apply(str);
}

练习五

public static void main(String[] args) {
    foreachArr(new IntConsumer() {
        @Override
        public void accept(int value) {
            System.out.print(value + ",");
        }
    });
}

public static void foreachArr(IntConsumer consumer){
    int[] arr = {1,2,3,4,5,6,7,8,9,10};
    for (int i : arr) {
        consumer.accept(i);
    }
}

lambda表达式：

public static void main(String[] args) {
    foreachArr((int value) -> {
            System.out.print(value + ",");
        }
    );
}

public static void foreachArr(IntConsumer consumer){
    int[] arr = {1,2,3,4,5,6,7,8,9,10};
    for (int i : arr) {
        consumer.accept(i);
    }
}