类不是抽象的，不会覆盖 Java 中的错误 [英] Class is not Abstract and does not Override error in Java

问题描述

我在使用 Java 时遇到编译时错误:

I am getting a compile time error with Java:

MyClass is not abstract and does not override abstract method
onClassicControllerRemovedEvent(
wiiusej.wiiusejevents.wiiuseapievents.ClassicControllerRemovedEvent)
in wiiusejevents.utils.WiimoteListener)

这是课程:

import wiiusej.WiiUseApiManager;
import wiiusej.Wiimote;
import wiiusej.wiiusejevents.physicalevents.ExpansionEvent;
import wiiusej.wiiusejevents.physicalevents.IREvent;
import wiiusej.wiiusejevents.physicalevents.MotionSensingEvent;
import wiiusej.wiiusejevents.physicalevents.WiimoteButtonsEvent;
import wiiusej.wiiusejevents.utils.WiimoteListener;
import wiiusej.wiiusejevents.wiiuseapievents.DisconnectionEvent;
import wiiusej.wiiusejevents.wiiuseapievents.NunchukInsertedEvent;
import wiiusej.wiiusejevents.wiiuseapievents.NunchukRemovedEvent;
import wiiusej.wiiusejevents.wiiuseapievents.StatusEvent;


public class MyClass implements WiimoteListener{

    public void onButtonsEvent(WiimoteButtonsEvent arg0) {
        System.out.println(arg0);
        if (arg0.isButtonAPressed()){
            WiiUseApiManager.shutdown();
        }
    }

    public void onIrEvent(IREvent arg0) {
        System.out.println(arg0);
    }

    public void onMotionSensingEvent(MotionSensingEvent arg0) {
        System.out.println(arg0);
    }

    public void onExpansionEvent(ExpansionEvent arg0) {
        System.out.println(arg0);
    }

    public void onStatusEvent(StatusEvent arg0) {
        System.out.println(arg0);
    }

    public void onDisconnectionEvent(DisconnectionEvent arg0) {
        System.out.println(arg0);
    }

    public void onNunchukInsertedEvent(NunchukInsertedEvent arg0) {
        System.out.println(arg0);
    }

    public void onNunchukRemovedEvent(NunchukRemovedEvent arg0) {
        System.out.println(arg0);
    }

    public static void main(String[] args) {
        Wiimote[] wiimotes = WiiUseApiManager.getWiimotes(1, true);
        Wiimote wiimote = wiimotes[0];
        wiimote.activateIRTRacking();
        wiimote.activateMotionSensing();
        wiimote.addWiiMoteEventListeners(new MyClass());
    }
}

我能更好地解释这个错误的含义吗?

Can I get a better explanation of what this error means?

推荐答案

如何尽可能简单地重现该错误:

Java 代码:

package javaapplication3;
public class JavaApplication3 {
    public static void main(String[] args) {
    }
}
class Cat implements Animal{

}

interface Animal{
    abstract boolean roar();
}

显示这个编译时错误:

Cat is not abstract and does not override abstract method roar() in Animal

为什么不能编译?

因为:

1. 您创建了一个实现接口 Animal 的 Cat 类.
2. 名为 Animal 的接口有一个名为 roar 的抽象方法，必须重写该方法.
3. 您没有提供方法咆哮.有很多方法可以消除编译时错误.

补救措施1，让Cat重写抽象方法roar()

package javaapplication3;

public class JavaApplication3 {
    public static void main(String[] args) {
        Cat c = new Cat();
        System.out.println(c.roar());
    }
}
class Cat implements Animal{ 
    public boolean roar(){
        return true;
    }
}

interface Animal{
    abstract boolean roar();
}

补救措施2，把Cat改成这样的抽象:

package javaapplication3;

public class JavaApplication3 {
    public static void main(String[] args) {
        Cat c;
    }
}
abstract class Cat implements Animal{ 

}
interface Animal{
    abstract boolean roar();
}

这意味着您不能再实例化 Cat.

Which means you can't instantiate Cat anymore.

补救措施 3，让 cat 停止执行 Animal

package javaapplication3;

public class JavaApplication3 {
    public static void main(String[] args) {
        Cat c = new Cat();
    }
}
class Cat{ 

}

interface Animal{
    abstract boolean roar();
}

这使得 roar() 不再是动物必须知道如何做的事情的契约.

Which makes roar() no longer a contract for things that animals must know how to do.

补救措施3，扩展一个类而不是实现一个接口

package javaapplication3;

public class JavaApplication3 {
    public static void main(String[] args) {
        Cat c = new Cat();
        System.out.println(c.roar());
    }
}
class Cat extends Animal{ 

}
class Animal{
    boolean roar(){
        return true;
    }
}

要使用的补救措施取决于代表所代表问题的最佳模型.该错误是在敦促您停止通过布朗运动编程".

The remedy to use depends on what the best model is to represent the problem being represented. The error is there to urge you stop "programming by brownian motion".

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