please help me again. i cant change the size of the square. pls help me.
Code:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class snakes extends JApplet
implements KeyListener, FocusListener, MouseListener {
// (Note: MouseListener is implemented only so that
// the applet can request the input focus when
// the user clicks on it.)
static final int SQUARE_SIZE = 20; // Length of a side of the square.
Color squareColor; // The color of the square.
int squareTop, squareLeft; // Coordinates of top-left corner of square.
boolean focussed = false; // True when this applet has input focus.
DisplayPanel canvas; // The drawing surface on which the applet draws,
// belonging to a nested class DisplayPanel, which
// is defined below.
public void init() {
// Initialize the applet; set it up to receive keyboard
// and focus events. Place the square in the middle of
// the applet, and make the initial color of the square red.
// Then, set up the drawing surface.
squareTop = getSize().height / 20;// - SQUARE_SIZE / 2;
squareLeft = getSize().width / 20;// - SQUARE_SIZE / 2;
squareColor = Color.red;
canvas = new DisplayPanel(); // Create drawing surface and
setContentPane(canvas); // install it as the applet's content pane.
canvas.setBackground(Color.white); // Set the background color of the canvas.
canvas.addFocusListener(this); // Set up the applet to listen for events
canvas.addKeyListener(this); // from the canvas.
canvas.addMouseListener(this);
} // end init();
class DisplayPanel extends JPanel {
// An object belonging to this nested class is used as
// the content pane of the applet. It displays the
// moving square on a white background with a border
// that changes color depending on whether this
// component has the input focus or not.
public void paintComponent(Graphics g) {
super.paintComponent(g); // Fills the panel with its
// background color, which is white.
/* Draw a 3-pixel border, colored cyan if the applet has the
keyboard focus, or in light gray if it does not. */
if (focussed)
g.setColor(Color.cyan);
else
g.setColor(Color.lightGray);
int width = getSize().width; // Width of the applet.
int height = getSize().height; // Height of the applet.
g.drawRect(0,0,width-1,height-1);
g.drawRect(1,1,width-3,height-3);
g.drawRect(2,2,width-5,height-5);
/* Draw the square. */
g.setColor(squareColor);
g.fillRect(squareLeft = 3, squareTop = 3, SQUARE_SIZE, SQUARE_SIZE);
/* If the applet does not have input focus, print a message. */
if (!focussed) {
g.setColor(Color.magenta);
g.drawString("Click to activate",7,20);
}
} // end paintComponent()
} // end nested class DisplayPanel
// ------------------- Event handling methods ----------------------
public void focusGained(FocusEvent evt) {
// The applet now has the input focus.
focussed = true;
canvas.repaint(); // redraw with cyan border
}
public void focusLost(FocusEvent evt) {
// The applet has now lost the input focus.
focussed = false;
canvas.repaint(); // redraw without cyan border
}
public void keyTyped(KeyEvent evt) {
// The user has typed a character, while the
// applet has the input focus. If it is one
// of the keys that represents a color, change
// the color of the square and redraw the applet.
char ch = evt.getKeyChar(); // The character typed.
if (ch == 'B' || ch == 'b') {
squareColor = Color.blue;
canvas.repaint();
}
else if (ch == 'G' || ch == 'g') {
squareColor = Color.green;
canvas.repaint();
}
else if (ch == 'R' || ch == 'r') {
squareColor = Color.red;
canvas.repaint();
}
else if (ch == 'K' || ch == 'k') {
squareColor = Color.black;
canvas.repaint();
}
} // end keyTyped()
public void keyPressed(KeyEvent evt) {
// Called when the user has pressed a key, which can be
// a special key such as an arrow key. If the key pressed
// was one of the arrow keys, move the square (but make sure
// that it doesn't move off the edge, allowing for a
// 3-pixel border all around the applet).
int key = evt.getKeyCode(); // keyboard code for the key that was pressed
if (key == KeyEvent.VK_LEFT) {
squareLeft -= 8;
if (squareLeft < 3)
squareLeft = 3;
canvas.repaint();
}
else if (key == KeyEvent.VK_RIGHT) {
squareLeft += 8;
if (squareLeft > getSize().width - 3 - SQUARE_SIZE)
squareLeft = getSize().width - 3 - SQUARE_SIZE;
canvas.repaint();
}
else if (key == KeyEvent.VK_UP) {
squareTop -= 8;
if (squareTop < 3)
squareTop = 3;
canvas.repaint();
}
else if (key == KeyEvent.VK_DOWN) {
squareTop += 8;
if (squareTop > getSize().height - 3 - SQUARE_SIZE)
squareTop = getSize().height - 3 - SQUARE_SIZE;
canvas.repaint();
}
} // end keyPressed()
public void keyReleased(KeyEvent evt) {
// empty method, required by the KeyListener Interface
}
public void mousePressed(MouseEvent evt) {
// Request that the input focus be given to the
// canvas when the user clicks on the applet.
canvas.requestFocus();
}
public void mouseEntered(MouseEvent evt) { } // Required by the
public void mouseExited(MouseEvent evt) { } // MouseListener
public void mouseReleased(MouseEvent evt) { } // interface.
public void mouseClicked(MouseEvent evt) { }
} // end class KeyboardAndFocusDemo
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