java继承内部类

测试了下一个类继承内部类

public class TestInner {public void testMethod() {Outer outer = new Outer();Extend extendObj = new Extend(outer);}public static void main(String[] args) {(new TestInner()).testMethod();}}class Outer {public Outer() {System.out.println("Outer");}class Inner {public Inner() {super();System.out.println("Inner");}}}class Extend extends Outer.Inner {public Extend(Outer outer) {outer.super();System.out.println("Extend outer");}}

比较纠结的地方是

Extend类的必须有以Outer实例为参数的构造函数，否则报错：

an enclosing instance that contains Outer.Inner is required