Java8 默认方法 default method

https://blog.csdn.net/u010003835/article/details/76850242

就是在接口里定义非抽象方法

public interface InterfaceA {
    default void foo() {
        System.out.println("InterfaceA foo");
    }

    default void foo1() {
        System.out.println("InterfaceA foo1");
    }
}