直接上菜

/*接口类*/
public interface MsgListener{
	public void afterMsgRecived(String msgData);
}

/*工具类*/
public class Tools{
	public static void getMsgData(String reciver,MsgListener listener){
		reciver+=reciver;
		//关键的来了
		listener.afterMsgRecived(reciver);
	}
}

//调用
public static void main(String[] args){
	String reciver="JACK THE REAPER";
	//调用
	Tools.getMsgData(reciver,new MsgListener(){
		@override
		public void afterMsgRecived(String msgData){
			System.out.println(msgData);
		}
	});
}

最后，yes,yes,你会看到控制台输出:"JACK THE REAPERJACK THE REAPER";