extendsaccessdemo.java

来自「这是清华大学编写的JAVA教材中所有题目的源代码！」· Java 代码 · 共 63 行

class Point
{
	private int x;
	protected int y;
	public int z;
	int f=1;
	
	public Point(int a,int b,int c)
	{
		x=a;y=b;z=c;
	}
	public void display()
	{
		//本类方法可访问本类所有变量
		System.out.println(" "+x+" "+y+" "+z+" "+f);
		System.out.println();
	}
		
}

class Circle extends Point
{
	int w;

	public Circle(int a,int b,int c,int d)
	{
		super(a,b,c);
		w=d;
	}
	public void change()
	{
		//x=4;	//子类方法不可访问父类private变量
		y=4;
		z=4;
		f=4;
	}
}
		

class ExtendsDemo
{
	public static void main(String args[])
	{
		Point p=new Point(1,1,1);
		p.display();
		//p.x=2;		//本类对象不可访问本类private变量
		p.y=2;
		p.z=2;
		p.f=2;
		p.display();
		
		Circle ci=new Circle(1,1,1,1);
		ci.display();
		//ci.x=3;	//子类对象不可访问父类private变量
		ci.y=3;
		ci.z=3;
		ci.f=3;
		ci.display();
			
		ci.change();
		ci.display();
	}
}