學習怎樣用java8去迴圈迭代

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");
	}
});
 

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);