java - 另一个继承类中的继承类

Question

我在 Java 中遇到继承问题。我将使用军队的例子:我有一个类(class)基础:

public class Soldier {
    Squad squad;

    public Soldier(Squad _squad) {
        squad = _squad;
    }
    //and some methods, that use squad 
}

我有:

public class Archer extends Soldier {
    public Archer(ArcherSquad _squad) {
        super(_squad);
    }
    //some new methods, some override 
}

和:

public class Warrior extends Soldier {
    public Warrior(WarriorSquad _squad) {
        super(_squad);
    }
    //some new methods, some override 
}

我的小队看起来像:

Squad;
ArcherSquad extends Squad(some new methods);
WarriorSquad extends Squad(some new methods);

现在我想从 Archer 访问 ArcherSquad 中的方法。如何在不破坏任何内容的情况下更改代码？

Answer 1

您可以将小队的引用移至 ArcherSquad

public abstract class Soldier {
    // force subclass supply some squad
    protected abstract Squad getSquad();
    public void someMethod() {
        Squad squad = getSquad();
        // do something with it.
    }
}

public class Archer extends Soldier {
    private ArcherSquad archerSquad;
    public Archer(ArcherSquad _squad) {
        archerSquad = _squad;
    }
    @Override
    protected Squad getSquad() {
        return archerSquad;
    }
    ...
}

或者你可以将Soldier变成一个泛型类

public class Soldier<T extends Squad> {
    protected T squad;

    public Soldier(T _squad) {
        this.squad = _squad;
    }

    public void someMethod() {
        Squad squad = this.squad;
        // do something with it.
    }
}

public class Archer extends Soldier<ArcherSquad> {

    public Archer(ArcherSquad _squad) {
        super(_squad);
    }

    public void someMethodUsingArcherSquad() {
        ArcherSquad as = squad;
    }
    // some new methods, some override
}