swing - Kotlin @JvmStatic 和伴随对象中的意外覆盖

Question

我正在使用 kotlin 开发 Swing 外观。为了创建 UI，Swing 需要有一个静态方法 createUI带有以下签名:

class ButtonUI: BasicButtonUI() {
    ...
    companion object {
        @JvmStatic fun createUI(p0: JComponent): ComponentUI {
           ...
        }
    }
}

然后通过 Swing 代码中的反射调用它:

m = uiClass.getMethod("createUI", new Class[]{JComponent.class});

不幸的是，上面的代码不能被 kotlin 编译器编译，因为:

Error:(88, 9) Kotlin: Accidental override: The following declarations have the same JVM signature (createUI(Ljavax/swing/JComponent;)Ljavax/swing/plaf/ComponentUI;):
    fun createUI(c: JComponent): ComponentUI
    fun createUI(p0: JComponent!): ComponentUI!

这种情况有解决方法吗？

Answer 1

这是一个 kotlin bug KT-12993 .不幸的是，该错误尚未修复。只使用 java实现你的ButtonUI或在 java 之间切换如果您想让 kotlin 实现您的 ui 逻辑，则使用 kotlin 来解决问题。例如，您应该定义一个 同行 java之间和 Kotlin 。

java代码如下:

public class ButtonUI extends BasicButtonUI {
    private ButtonUIPeer peer;

    public ButtonUI(ButtonUIPeer peer) {
        this.peer = peer;
    }

    @Override
    public void installUI(JComponent c) {
        peer.installUI(c, () -> super.installUI(c));
    }

    // override other methods ...


    public static ComponentUI createUI(JComponent c) {
        // create the peer which write by kotlin 
        //                        |
        return new ButtonUI(new YourButtonUIPeer());
    }
}


interface ButtonUIPeer {
    void installUI(Component c, Runnable parentCall);
    //adding other methods for the ButtonUI
}

kotlin 代码如下:

class YourButtonUIPeer : ButtonUIPeer {
    override fun installUI(c: Component, parentCall: Runnable) {
      // todo: implements your own ui logic
    }
}

中频你有超过半打的方法来实现，你可以使用 Proxy Design Pattern只需将请求委托(delegate)给目标 ButtonUI它在 kotlin 中实现(许多 IDE 支持为字段生成委托(delegate)方法)。例如:

public class ButtonUIProxy extends BasicButtonUI {
    private final BasicButtonUI target;
    //1. move the cursor to here ---^
    //2. press `ALT+INSERT`
    //3. choose `Delegate Methods` 
    //4. select all public methods and then click `OK`

    public ButtonUIProxy(BasicButtonUI target) {
        this.target = target;
    }

    public static ComponentUI createUI(JComponent c){
        // class created by kotlin     ---v
        return new ButtonUIProxy(new ButtonUI());
    }
}