Java内置函数式接口的举例

1.介绍

Java内置4大函数式接口

消费性接口 Consumer    void accept(T t)
供给型接口 Supplier    T get()
函数型接口 Function    R apply(T t)
断定型接口 Predicate    boolean test(T t) 

举例：

    @Test
	public void test1() {
		happyTime(500, new Consumer () {

			@Override
			public void accept(Double t) {
				System.out.println("学习太累了，"
						+ "去天上人间买了瓶矿泉水，价格为"+t);
			}
			
		});
		System.out.println("===========================");
		
		happyTime(400, money->{System.out.println("学习太累了,去天上人间买了瓶矿泉水，价格为"+money);});
	}
	
	public void happyTime(double money ,Consumer con) {
		con.accept(money);
	}

    @Test
	public void test2() {
		List list=Arrays.asList("北京","南京","天津","东京","西京","普京");
		List filterStrs=filterString(list,new Predicate () {

			@Override
			public boolean test(String t) {
				return t.contains("京");
			}
			
		});
		System.out.println(filterStrs);
		
		System.out.println("===================");
		
		List filterStr2=filterString(list, s->s.contains("京"));
		System.out.println(filterStr2);
	}
	
	//根据给定的规则，过滤集合中的字符串，此规则由Predicate的方法决定
	public  List filterString(List list, Predicate pre){
		ArrayList filterList=new ArrayList<>();
		for(String s:list) {
			if(pre.test(s)) filterList.add(s);
		}
		return filterList;
	}