shape.java

来自「Java 入门书的源码」· Java 代码 · 共 58 行

//Copyright (c) 1998, Arthur Gittleman
//This example is provided WITHOUT ANY WARRANTY either expressed or implied.

import java.awt.Point;
public abstract class Shape {
  Point center;     
  public Shape() { 
    center =  new Point(0,0);
  }
  public Shape(Point p) {
    center = p;
  }
  public abstract void draw();
  public String toString(){                            
    return "Shape with center " + center;
  }
  public void move(int xamount, int yamount) {
    center.translate(xamount,yamount);
  }
  public static void main(String argv[]) {
    Shape s0 = new Line(2,5,6,7);
    Shape s1 = new Circle( new Point(3,4) ,5); 
    s0.move(3,-1);
    s0.draw(); 
    s1.move(3,-1);
    s1.draw();
  }
}
class Line extends Shape {
  Point end;
  public Line(int x1, int y1, int x2, int y2) {
    super(new Point(x1,y1));
    end = new Point(x2,y2); 
  }
  public void draw() {
    System.out.println(toString());
  }
  public String toString() {
    return  "Line from "+center + " to " + end;
  }
  public void move(int xamount, int yamount) {
    super.move(xamount,yamount);
    end.translate(xamount,yamount);
  }
}
class Circle extends Shape {
  int radius;
  public Circle(Point p, int r) {
    super(p);
    radius = r;
  }
  public void draw() {
    System.out.println(toString());
  }
  public String toString() {
    return "Circle at "+center+" with radius "+radius;
  }
}