java - 重写父类

Question

我有我的 Pet 父类(super class)，它还有一个 Dog 子类，我的父类(super class)中的一个特定方法是 getSpecies()。在我的子类中，我希望能够返回 super.getSpecies() ，而且还在该方法内返回另一个变量(在本例中为气味)。

super 类:

public class Pet {
    protected int lifeSpan;
    protected  String species, name, interaction;

    public Pet(){
    }

    public Pet(int lifeSpan, String species, String name){
        this.lifeSpan = lifeSpan;
        this.species = species;
        this.name = name;
    }

    public final float costs(float cost){
        return cost;
    }

    public void setSpecies(String species){
        this.species = species;
    }

    public String getSpecies(){
        return this.species;
    }
}

子类“狗”:

public class Dog extends Pet{
    protected String smell;
    private String species;

    public Dog(String smell){
        super(15, "Dog", "Rex");
        this.smell = smell;
    }

    public Dog(){

    }

    public void setSmell(String smell){
        this.smell = smell;
    }

    public String getSpecies(){
       super.getSpecies();
       smell = "high"; //Meant to deliberately set it to "High". How am I to return this?
    }

    public String getSmell(){
        return this.smell;
    }
}

Answer 1

不能在单个函数中返回两个值。你所要做的就是使用你的 getter 来替代气味成员变量。

public class Dog extends Pet{
    protected String smell;
    private String species;

    public Dog(String smell){
        super(15, "Dog", "Rex");
        this.smell = smell;
    }

    public Dog(){

    }

    public void setSmell(String smell){
        this.smell = smell;
    }

    public String getSpecies(){
       super.getSpecies();
    }

    public String getSmell(){
        return this.smell;
    }

}

然后假设您想要物种和气味，您必须检查宠物是否实际上是狗，如果是，您可以安全地将其转换为狗并使用 Dog 类的特定方法。

if ( pet instanceof Dog ) {
    String species = pet.getSpecies();
    String smell = (Dog)pet.getSmell();
}