import java.awt.*;         // Needed for Graphics
import javax.swing.*;      // Needed for JFrame
import java.awt.event.*;   // Needed for Key

public class key extends JFrame implements KeyListener
{

	char c;

    public static void main(String[] args) {
	new key();
    }
    public key()
    {
		c = ' ';
		addKeyListener(this);
        setSize(800, 800);
        setVisible(true);
    }

    public void paint(Graphics gfx) {
		if(c == 'r') gfx.setColor(Color.red);
		else if(c == 'b') gfx.setColor(Color.blue);
		else if (c == 'g') gfx.setColor(Color.green);
		else gfx.setColor(Color.black);
		gfx.fillRect(100,100,500,500);
	}
	
	public void keyPressed(KeyEvent e){ c = e.getKeyChar(); repaint();}
	public void keyReleased(KeyEvent e){}
	public void keyTyped(KeyEvent e){}
}