父类应用指向子类对象，小弟我这种写不知道错哪了，请帮小弟我看看-Java教程-爱易网页

父类应用指向子类对象，小弟我这种写不知道错哪了，请帮小弟我看看

日期：2014-05-20　浏览次数：20951 次

父类应用指向子类对象，我这种写不知道哪里错了，请帮我看看
小弟初接触Java,请各位高手帮我修改下，

Java code

class Animals
{
    private String color;
    private int high;
    Animals(){
    }
    Animals(String color,int high){
        this.color = color;
        this.high = high;
    }
    
    public void info(Animals a){
        System.out.println("color="+a.color);
        if (a instanceof Bird)
        {
            Bird bird = (Bird) a;
            System.out.println("name="+bird.name+"  high="+bird.high);
        }
        else 
            System.out.println("I'd not konw who is this");
        }
}
class Bird extends Animals
{
    private String name;
    Bird(){
    }
    Bird(String name,String color,int high){
        super(color,high);
        this.name = name;
    }
    
}
public class FatherSub
{
    public static void main(String arg[]){
    Animals a = new Animals();
    Bird b = new Bird("john","blue",12);
    a.info(b);

}
}

错误提示：FatherSub.java:28: name has private access in Bird
System.out.println("name="+bird.name+" high="+bird.high);
^
FatherSub.java:28: high has private access in Animals
System.out.println("name="+bird.name+" high="+bird.high);
^
2 errors

------解决方案--------------------
因为name是Bird的，你想在Animal里面用了
可以在Bird定义一个public String getName() {return name}

然后在需要用到Bird的name的地方用getName返回就好
------解决方案--------------------
类中的private 属性，写上getter和 setter方法，使用的时候用xxx.getName() ;
------解决方案--------------------

Java code


package test;

class Animals{
    private String color;
    private int high;
    Animals(){}
    Animals(String color,int high){
        this.color = color;
        this.setHigh(high);
    }
    
    public void info(Animals a){
        System.out.println("color="+a.color);
        if (a instanceof Bird){
            Bird bird = (Bird) a;
            System.out.println("name="+bird.getName()+"  high="+bird.getHigh());
        }else 
            System.out.println("I'd not konw who is this");
    }
    
    public void setHigh(int high) {
        this.high = high;
    }
    public int getHigh() {
        return high;
    }
}

class Bird extends Animals{
    private String name;
    Bird(){}
    Bird(String name,String color,int high){
        super(color,high);
        this.setName(name);
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getName() {
        return name;
    }
    
}

public class FatherSub{
    public static void main(String arg[]){
        Animals a = new Animals();
        Bird b = new Bird("john","blue",12);
        a.info(b);
    }
}

------解决方案--------------------
class Animals {
	private String color;
	protected int high;

	Animals() {
	}

	Animals(String color, int high) {
		this.color = color;
		this.high = high;
	}

	public void info(Animals a) {
		System.out.println("color=" + a.color);
		if (a instanceof Bird) {
			Bird bird = (Bird) a;
			System.out.println("name=" + bird.name + "  high=" + bird.high);
		} else
			System.out.println("I'd not konw who is this");
	}
}

class Bird extends Animals {
	String name;

	Bird() {
	}

	Bird(String name, String color, int high) {

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父类应用指向子类对象，小弟我这种写不知道错哪了，请帮小弟我看看

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