需要額外增加一個Interface接口才行。

class?Test??
{
	public?static?void?main?(String[]?args)
	{
	????Test?t?=?new?Test();
	????MyInner?inner?=?t.getInner();
	????inner.innerTest();
	}
	
	public?MyInner?getInner()?{
	????class?Inner?implements?MyInner{
	????????public?void?innerTest()?{
	????????????System.out.println("innerTest");
	????????}
	????}
	????return?new?Inner();
	}
}

interface?MyInner{
????void?innerTest();
}

class?Outer{??//定義一個外部類
	private?String?msg="Hello?World!";
	public?void?fun(){
	class?Inner{?//定義一個內部類
		???public?void?print(){
			??System.out.println(Outer.this.msg);
		??}
	}
	?new?Inner().print();
	}
	
}
public?class?TestOuter?{

	public?static?void?main(String[]?args)?{
		new?Outer().fun();
	}

}