import java.awt.*;import java.awt.event.*;import javax.swing.*;class ControlledBall extends JPanel{int diameter = 30;int height = 30;int x_Pos = 0;int y_Pos;ControlledBall() { Jframe fr = new Jframe("Controlled Ball"); fr.setDefaultCloseOperation(Jframe.EXIT_ON_CLOSE); this.setBackground(Color.red); setPreferredSize(new Dimension(400,300)); fr.add(this); fr.setVisible(true); // important! fr.pack(); //fr.setSize(600,400); y_Pos = this.getHeight()/2; register(); repaint();}public void register() { // very important! setFocusable(true); this.addKeyListener(new KeyAdapter() { public void keyPressed(KeyEvent ke) { if( ke.getKeyCode() == ke.VK_RIGHT ) {increment(); } else if( ke.getKeyCode() == ke.VK_LEFT ) {decrement(); } else if( ke.getKeyCode() == ke.VK_UP) {jump(); } } });}public void paintComponent(Graphics g) { super.paintComponent(g); g.setColor( Color.orange ); g.fillOval( x_Pos , y_Pos , diameter , height );}public void increment() { x_Pos++; if( x_Pos > (this.getWidth() - diameter) ) { x_Pos = this.getWidth() - diameter; } repaint();}public void decrement() { x_Pos--; if( x_Pos <= 0) { x_Pos = 0; } repaint();}public void jump() { y_Pos++; if( y_Pos <=0 ) { y_Pos = 0; }repaint();} public static void main( String args[] ) { new ControlledBall(); }}
