java新特性之Stream，演变过程

遍历数组1.0

public static void ergodicList(List<Integer> list){

        for (int i = 0; i < list.size(); i++) {

            System.out.println(list.get(i));
        }


    }

看一下编译出的字节码

遍历List1.5

public static void ergodicList(List<Integer> list){

        for (Integer temp : list) {

            System.out.println(temp);
        }


    }

编译结果

遍历List 2.0

public static void ergodicList(List<Integer> list){

        Stream<Integer> stream = list.stream();

        // 使用consumer接口实现方法
        Consumer<Integer> consumer = new Consumer<Integer>() {

            @Override
            public void accept(Integer temp) {
                System.out.print(temp);
            }
        };

        stream.forEach(consumer);


    }

编译结果

遍历List 2.5

public static void ergodicList(List<Integer> list){

        Stream<Integer> stream = list.stream();

        Consumer<Integer> consumer = (num) -> {
            System.out.print(num);
        };



        stream.forEach(consumer);


    }

编译结果

遍历List 3.0

public static void ergodicList(List<Integer> list){

        Stream<Integer> stream = list.stream();

        Consumer<Integer> consumer = num -> System.out.print(num);

        stream.forEach(consumer);


    }

编译结果和2.5一样

遍历List 3.5

public static void ergodicList(List<Integer> list){

        Stream<Integer> stream = list.stream();

        stream.forEach(System.out::print);

    }

编译结果

遍历List 4.0

public static void ergodicList(List<Integer> list){

        list.stream().forEach(System.out::print);

    }

编译结果和3.5一样

三重奏

不熟悉之前，先写匿名内部类，再逐步过度到lambda表达式

实在不行，先写匿名内部类，再在内名函数上用alt+enter，替换成lambda