来自匿名内部类的外部类的关键字

public class A {
    public static int x = 10;
    public static void y() {
        System.out.println("Hello, world!");
    }
    public void method() {
        B b = new B();
    }
    private class B {
        public void print() {
            System.out.println(A.x);
            A.y();
        }
    }
}