sketch.java

this is my project by java

import java.awt.*;
import java.awt.geom.*;
import java.util.*;
import java.awt.event.*;
import javax.swing.*;

public class Sketch {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		SketchFrame frame=new SketchFrame();
		//SketchPanel j=new SketchPanel();
		//j.addKeyListener(this);
	    //frame.addKeyListener(this.KeyHandler);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setVisible(true);
		

	}
}
class SketchFrame extends JFrame
{
	public SketchFrame()
	{
		setTitle("Sketch");
		Toolkit kit=Toolkit.getDefaultToolkit();
		Dimension  screenSize=kit.getScreenSize();
		int screenHeight=screenSize.height;
		int screenWidth=screenSize.width;
		setSize(screenWidth/2,screenHeight/2);
		setLocation(screenWidth/4,screenHeight/4);
		
		//setSize(DEFAULT_WIDTH,DEFAULT_HEIGHT);
		SketchPanel panel=new SketchPanel();
		add(panel);
		
	}
	//public static final int DEFAULT_WIDTH=300;
	//public static final int DEFAULT_HEIGHT=200;
}
class SketchPanel extends JPanel
{
	public SketchPanel()
	{
		last=new Point2D.Double(100,100);
		lines=new ArrayList<Line2D>();
		KeyHandler listener=new KeyHandler();
		addKeyListener(listener);
		setFocusable(true);
	}
	public void add(int dx,int dy)
	{
		Point2D end=new Point2D.Double(last.getX()+dx,last.getY()+dy);
		Line2D line=new Line2D.Double(last,end);
		lines.add(line);
		repaint();
		last=end;
		
	}
	public void paintComponent(Graphics g)
	{
		super.paintComponent(g);
		Graphics2D g2=(Graphics2D) g;
		for(Line2D l:lines)
			g2.draw(l);
	}
	private Point2D last;
	private ArrayList<Line2D> lines;
	private static final int SMALL_INCREEMENT=1;
	private static final int LARGE_INCREEMENT=5;
	
	private class KeyHandler extends KeyAdapter
	{
		public void keyPressed(KeyEvent event)
		{
			int KeyCode=event.getKeyCode();
			int d;
			if(event.isShiftDown())
				d=LARGE_INCREEMENT;
			else
				d=SMALL_INCREEMENT;
			if(KeyCode==KeyEvent.VK_LEFT) add(-d,0);
			else if(KeyCode==KeyEvent.VK_RIGHT) add(d,0);
			else if(KeyCode==KeyEvent.VK_UP) add(0,-d);
			else if(KeyCode==KeyEvent.VK_DOWN) add(0,d);
			
		}
	    public void keyReleased(KeyEvent event){}
		public void keyTyped(KeyEvent event)
		{
			char KeyChar=event.getKeyChar();
			int d;
			if(Character.isUpperCase(KeyChar))
			{
				d=LARGE_INCREEMENT;
				KeyChar=Character.toLowerCase(KeyChar);
			}
			else
				d=SMALL_INCREEMENT;
			if(KeyChar=='h') add(-d,0);
			else if (KeyChar=='l') add(d,0);
			else if (KeyChar=='k') add(0,-d);
			else if (KeyChar=='j') add(0,d);
			
		}
	}
	
}