java中lambda(函数式编程)一行解决foreach循环问题

    @Test
    public void forTest() {
        // 实例化一个List
        List<Point> points = Arrays.asList(new Point(1, 2), new Point(2, 3));
        System.out.println("循环操作前：" + points);
        // for循环
        for (int i = 0; i < points.size(); i++) {
            points.get(i).translate(1, 1);
        }
        System.out.println("循环操作后：" + points);
    }

    @Test
    public void forEachTest() {
        List<Point> points = Arrays.asList(new Point(1, 2), new Point(2, 3));
        System.out.println("循环操作前：" + points);
        // foreach 循环
        for (Point p : points) {
            p.translate(1, 1);
        }
        System.out.println("循环操作后：" + points);
    }

    @Test
    public void forEachMethodTest() {
        List<Point> points = Arrays.asList(new Point(1, 2), new Point(2, 3));
        System.out.println("循环操作前：" + points);
        
        points.forEach(new Consumer<Point>() {
            public void accept(Point t) {
                t.translate(1, 1);
            }
        });
        System.out.println("循环操作后：" + points);
    }

    default void forEach(Consumer<? super T> action) {
        Objects.requireNonNull(action);
        for (T t : this) {
            action.accept(t);
        }
    }

    @Test
    public void lambdaForEachTest() {
        List<Point> points = Arrays.asList(new Point(1, 2), new Point(2, 3));
        System.out.println("循环操作前：" + points);
        
        points.forEach(p -> p.translate(1, 1));
        System.out.println("循环操作后：" + points);
    }

    public int add(int x, int y) {
        return x + y;
    }

    (x, y) -> x + y; //返回两数之和

    Map<String, Integer> items = new HashMap<>();
    items.put("A", 10);
    items.put("B", 20);
    items.put("C", 30);
    items.put("D", 40);
    items.put("E", 50);
    items.put("F", 60);
    for (Map.Entry<String, Integer> entry : items.entrySet()) {
        System.out.println("Item : " + entry.geTKEy() + " Count : " + entry.getValue());
    }

    Map<String, Integer> items = new HashMap<>();
    items.put("A", 10);
    items.put("B", 20);
    items.put("C", 30);
    items.put("D", 40);
    items.put("E", 50);
    items.put("F", 60);    
    items.forEach((k,v)->System.out.println("Item : " + k + " Count : " + v));
    items.forEach((k,v)->{
        System.out.println("Item : " + k + " Count : " + v);
        if("E".equals(k)){
            System.out.println("Hello E");
        }
    });