Java8新特性之函数式接口

Java8内置函数式接口

Consumer< T > ：消费者接口

@Test
public void test01(){
    //Consumer
    Consumer<Integer> consumer = (x) -> System.out.println("消费" + x);
    //test
    consumer.accept(1000);
}

Supplier< T > : 供给型接口

  @Test
    public void test04 () {
        List list = getNum (10, () -> (int) (Math.random () * 100));
        list.forEach (System.out :: println);
    }

	//返回num个随机数
    public List<Integer> getNum (int num, Supplier<Integer> supplier) {
        List<Integer> list = new ArrayList<> ();
        for (int i = 0; i < num; i++) {
            list.add (supplier.get ());
        }
        return list;
    }

Function< T, R > ： 函数型接口

@Test
    public void test05 () {
        String s = strHandler (" 156 1CNDJINCD bjc AGVCHSDBCK  ", String :: toLowerCase);
        System.out.println (s);
    }

    public String strHandler (String str, Function<String, String> function) {
        return function.apply (str);
    }

Predicate< T > ： 断言型接口

@Test
public void test04(){
    Integer age = 70;
    Predicate<Integer> predicate = (i) -> i >= 35;
    if (predicate.test(age)){
        System.out.println("你该退休了");
    } else {
        System.out.println("hhh");
    }
}

其他接口

自定义函数式接口

@FunctionalInterface
public interface MyFunction {
    Integer count(Integer a, Integer b);
}

@Test
public void test05(){
    Integer result = operation(3, 5, (x, y) -> x + y);
    System.out.println(result);
}

public Integer operation(Integer a, Integer b, MyFunction myFun){
    return myFun.count(a, b);
}