Question

我有以下内容：

抽象类BaseScore
LevelScore这是BaseScore

然后我有：

抽象类BaseScoreRecord

public abstract class BaseScoreRecord<T extends BaseScore> {
     public BaseScoreRecord(){
        init();
     }

     protected T[] mScoreHistory;
     protected int count=0;
     protected float finalScore;

     protected abstract void calcFinalScore();
     protected abstract void init();

     public float getFinalScore() {
         return mFinalScore;
     }

     public void addScoreRecord(T score){
         mScoreHistory[count] = score;
         count++;
     }
}

...和MyScoreRecord是BaseScoreRecord

的子类

public class MyScoreRecord extends BaseScoreRecord<LevelScore> {
     public MyScoreRecord(){
        init();
     }

     @Override
     protected void calcFinalScore(){
         //Does some stuff to calc final score from mScoreHistory
     }

     @Override
     protected void init(){
         mScoreHistory = new LevelScore[10];
         for (int i=0;i<mScoreHistory.length;i++){
             mScoreHistory[i] = new LevelScore();
         }
     };
}

那么，我有BaseGame，其中包含以下行：

protected BaseScoreRecord<? extends BaseScore> endGameRecord;

...和MyGame是BaseGame的子类。 MyGame包括以下方法：

@Override
protected void gameInit(){
    endGameRecord = new MyScoreRecord();  //endGameRecord initialised
}


protected void addLevelScore(LevelScore ls){
    mEndGameRecord.addScoreRecord(ls);
}

我在最后一个方法上遇到编译器错误：

The method addScoreRecord(capture#3-of ? extends BaseScore) 
in the type BaseScoreRecord <capture#3-of ? extends BaseScore>
is not applicable for the arguments (LevelScore)

...所以我显然在泛型，通配符和子类化方面做错了。如果我在BaseGame和MyGame中丢失了泛型，那么它似乎运行时没有任何令人讨厌的ClassCastException错误。任何指针都将非常感激。也许我为自己弄得太复杂了？

Answer 1

您应该声明MyScoreRecord实际上是BaseScoreRecord的子类，并正确地对其进行参数化：

public class MyScoreRecord extends BaseScoreRecord<LevelScore>

例如，如果您正在使用Eclipse，则会收到警告，因为@Override注释实际上并未覆盖任何内容。上述内容还将使编译器强制LevelScore扩展BaseScore。

与Java泛型和子类化混淆

1 个答案: