学习怎样用java8去循环迭代

1、Map

Map<Integer, String> items = new HashMap<>(); items.put(1, "wangwu"); items.put(2, "zhangsan"); items.put(3, "lisi"); items.forEach((k,v)->System.out.println("Item : " + k + " Count : " + v)); items.forEach((k,v)->{ System.out.println("Item : " + k + " Count : " + v); if("zhansan".equals(k)){ System.out.println("Hello zhangsan"); } });

2、List

List<String> items = new ArrayList<>(); items.add("A"); items.add("B"); items.add("C"); items.add("D"); items.add("E"); //lambda //Output : A,B,C,D,E items.forEach(item->System.out.println(item)); //Output : C items.forEach(item->{ if("C".equals(item)){ System.out.println(item); } }); //method reference //Output : A,B,C,D,E items.forEach(System.out::println); //Stream and filter //Output : B items.stream() .filter(s->s.contains("B")) .forEach(System.out::println);