Java中對象轉換

←手機掃碼閱讀火星人 @ 2014-03-10 , reply:0

Java的變數類型之間可以進行轉換,對象之間也可以.

子類對象轉為父類對象,可以不進行強制轉換,因為子類繼承父類對象.

但是,當父類對象轉換為子類對象時（當且僅當父類對象本來是由子類默認轉換過去的情況）,可以對父類對象進行強制轉換.

public class TestObject { public static void main(String[] args) { // TODO Auto-generated method stub Animal a = new Animal(); Dog d = new Dog("yellow"); d.name = "bigYellow"; System.out.println( a.print( d ) ); }

                 }

class Animal{
    String name;
    
    public void setName(String n){
        this.name = n;
    }
    
    public String getName(){
        return this.name;
    }
    
    public String print(Animal a){
        String result = "";
        if (a instanceof Dog) {
            Dog d = (Dog)a;
            result = "Name:"   a.name   "n"   "FurColor:"   d.furColor;
        }else if (a instanceof Cat) {
            Cat c = (Cat)a;
            result = "Name:"   a.name   "n"   "EyeColor:"   c.eyeColor;
        }else{
            result = "Name:"   a.name;
        }
        return result;    
    }
        
                 }

class Cat extends Animal{
    String eyeColor;
    public void setEyeColor(String e){
        this.eyeColor = e;
    }
    public String getEyeColor(){
        return this.eyeColor;
    }
    
    Cat(String e){
        this.setEyeColor(e);
    }
}

class Dog extends Animal{
    String furColor;
    public void setFurColor(String f){
        this.furColor = f;
    }
    public String getFurColor(){
        return this.furColor;
    }
    
    Dog (String d){
        this.setFurColor(d);
    }
        
                 }

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Java中對象轉換

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