函数式接口

函数式接口

函数式接口的特点？

接口有且仅有一个抽象方法，抽象方法只没有实现的方法
允许定义静态非抽象方法
允许定义默认default非抽象方法（default方法也是java8才有的）
允许java.lang.Object中的public方法，如上图的方法equals
@FunctionInterface注解不是必须的

实践

编写自定义的Compatator接口

    @Test
    public void test7() {
        Employee e1 = new Employee(1, 21, "zhangsan", "F");
        Employee e2 = new Employee(2, 45, "lisi", "M");
        Employee e3 = new Employee(3, 60, "wangwu", "M");
        Employee e4 = new Employee(4, 32, "zhouliu", "F");
        Employee e5 = new Employee(5, 28, "zhaoqi", "M");
        Employee e6 = new Employee(6, 43, "qianba", "F");

        List<Employee> list = Arrays.asList(e1, e2, e3, e4, e5, e6);
        list.sort(new Comparator<Employee>() {
            @Override
            public int compare(Employee o1, Employee o2) {
                return o2.getAge() - o1.getAge();
            }
        });
        list.forEach(System.out::println);
    }