泛型不起作用的覆盖方法（未找到方法） [英] Overriding method with generics not working (no method found)

问题描述

我正在尝试 @Override 类中的方法可能看起来像一个复杂的继承结构，但实际上它应该非常简单，但我无法得到它工作。

I am trying to @Override a method in a class that might look like having a complex inheritance structure, but it should actually be quite simple, however I cannot get it to work.

public interface Action { }

public interface Result { }

public interface Player<A extends Action, R extends Result> {
    default public <P extends Player<A, R>> void onPostAction(final P target, final A action, final R result) { }
}

abstract public class GesturePlayer<A extends Action, R extends Result> implements Player<A, R> { }

abstract public class RPSPlayer extends GesturePlayer<RPSGesture, RPSResult> { }

public class RPSHumanPlayer extends RPSPlayer {
    @Override
    public void onPostAction(final RPSPlayer target, final RPSGesture gesture, final RPSResult result) { }
}

我在 @Override 上收到错误 onPostAction ，为什么找不到正确的方法来覆盖？

I get the error on the @Override of the onPostAction, why can it not find the correct method to override?

这是针对Rock-Paper-剪刀实现让人想知道这个名字的来源。

This is for a Rock-Paper-Scissors implementation for people wondering where the name comes from.

确切的错误信息：

方法不会覆盖或实现超类型的方法

method does not override or implement a method from a supertype

我的目标是仍然使用当前的类，所以对于 RPSHumanPlayer 我实际上想要这个签名：

My goal is to still use the current class, so for RPSHumanPlayer I would actually want to have this signature:

public void onPostAction(final RPSHumanPlayer target, final RPSGesture gesture, final RPSResult result) { }

推荐答案

Player 中的方法 onPostAction 本身就是通用的。您已经在那里定义了 P 。因此，任何覆盖它的方法也必须是通用的。

The method onPostAction in Player is itself generic. You have defined P there. Therefore, any method that overrides it must also be generic.

尝试

public class RPSHumanPlayer extends RPSPlayer {
    @Override
    public <P extends Player<RPSGesture, RPSResult>> void onPostAction(final P target,
       final RPSGesture gesture, final RPSResult result) { }
}

A 和 R 已由 GesturePlayer定义要 RPSGesture 和 RPSResult ，但 P 仍然需要申报。

A and R are already defined by GesturePlayer to be RPSGesture and RPSResult, but P still needs to be declared.

加法

如果需要确切的话签名，然后你必须定义 P 以及 A 和 R 播放器界面上的c $ c>：

If it needs to be that exact signature, then you'll have to define P along with A and R on the Player interface:

public interface Player<A extends Action, R extends Result, P extends Player<A, R, P>> {
    default public void onPostAction(final P target, final A action, final R result) { }
}

然后 GesturePlayer 相应更改：

abstract public class GesturePlayer<A extends Action, R extends Result,
     P extends Player<A, R, P>> implements Player<A, R, P> { }

然后 RPSPlayer 将自己定义为 P 。

abstract public class RPSPlayer extends GesturePlayer<RPSGesture, RPSResult, RPSPlayer> { }

和 RPSHumanPlayer 可以有方法原样：

public class RPSHumanPlayer extends RPSPlayer {
    @Override
    public void onPostAction(final RPSPlayer target, final RPSGesture gesture, final RPSResult result) { }
}

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