extenddemo.java

java课程的资料以及实验的代码

  class Point2D {
  static int x=10;
   static private int y; 
 
    public Point2D() {
    } 

    public Point2D(int x, int y) {
        //this.x = x; 
        this.y = y;
    }

   // public void setX(int x) { this.x = x; }
    public void setY(int y) { this.y = y; } 

     int getX() { return x; }
     int getY() { return y; } 
     public static void display()
     {
     	System.out.println("x="+x);
     	System.out.println("y="+y);
     }
     
}
class Point3D extends Point2D { // 扩展Point2D类  
    private int z;
    private int x;  // 新增私有数据 
 
    public Point3D() {
     
        super();
        //super.x=100;
    } 
    // 定义建构方法 
    Point3D(int x, int y, int z) { 
        super(x, y); //同时指定呼叫父类构造函数
        this.z = z; 
    }  
    // 新增方法
    public void setZ(int z) { this.z = z; }
    public int getZ() { return z; }
    public static void display()
    {
    	Point2D.display();
    //System.out.println("z="+z);
    }
}
public class ExtendDemo { 
    public static void main(String[] args) { 
        Point3D p1 = new Point3D(1, 3, 4); 
        Point3D p2 = new Point3D(); 
        Point2D p3 =new Point2D();
        new Point3D().display();
        System.out.println("p1: (%d, %d, %d) \n"+
            p1.getX()+ p1.getY()+ p1.getZ());
            //Object obj=new Object();
            
        System.out.println("p2: (%d, %d, %d) \n"+
            p2.getX()+ p2.getY()+ p2.getZ()); 
            p3.display();
    } 
}