line.java

能够画线条、圆和长方形的Java程序

import java.awt.Color;
import java.awt.Graphics;


public class Line extends Shape {
	private int x, y, x2, y2;
		
	public Line(int x, int y, int x2, int y2){
		this.x = x;
		this.y = y;
		this.x2 = x2;
		this.y2 = y2;
	}
	
	
	public void draw(Graphics g){
		Color c = g.getColor();
		
		if( isVisible() == false ){
			g.setColor( getBackgroundColor() );			
		}		
		g.drawLine( x , y, x2, y2);		
		g.setColor( c );
	}

	
	public int compareTo(Object obj) {
		System.out.println("comparing lines");
		if (obj instanceof Line){
			Line line = (Line)obj;
			if( ((this.x2 - this.x)* (this.x2 - this.x)+ (this.y2 - this.y) * (this.y2 - this.y))
				< ((line.x2 - line.x) * (line.x2 - line.x) + ( line.y2 - line.y ) * ( line.y2 - line.y )))
				return -1;
			if( ((this.x2 - this.x)* (this.x2 - this.x)+ (this.y2 - this.y) * (this.y2 - this.y))
				> ((line.x2 - line.x) * (line.x2 - line.x) + ( line.y2 - line.y ) * ( line.y2 - line.y )))
				return 1;
		}		
		
		return 0;
	}
	

}