uptriangle.java

Java程序设计(美) David D. Riley著 机械工业出版社 书籍配套 代码

import javax.swing.JComponent;
import java.awt.*;
public class UpTriangle extends JComponent  {
	/**	post:	getX() == x-h/2  and  getY() == y+h/2
	 *          and getWdith()==h/2  and  getHeight()==h/2 
     */
	public UpTriangle(int x, int y, int h )   {
		super();
		setBounds(x-h/4, y-h, h/2, h/2);
	}
	
	/**	post:	a black triangle is drawn with apex at the top
     *          center and the lower left and right corners of 
     *          the bounding rectangle 
     */
	public void paint(Graphics g)   {
		g.setColor(Color.black);
		g.drawLine(getWidth()/2, 0, getWidth()-1, getHeight()-1);
		g.drawLine(getWidth()-1, getHeight()-1, 0, getHeight()-1);
		g.drawLine(0, getHeight()-1, getWidth()/2, 0);
	}
}