Help event handling

Question

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class DemoWindow extends JFrame
     private final int WIDTH = 200, HEIGHT = 200;
     public DemoWindow() {
          //set title
          setTitle( "Event-Handling Demostration" );
          //get screen size
          Dimension d = this.getToolkit().getScreenSize();
          //1. if u want the fram to fill the whole screen use this code
          setLocation( 0, 0 );   //may not need because it's default
          setSize( d.width, d.height );
          //2. if u have a custom frame size use this code to
          //   dynamically center it (assume the given size at top)
          setSize( WIDTH, HEIGHT );
          setLocation( (d.width-this.getWidth()) / 2,
          (d.height-this.getHeight())/ 2 );
          //to end program when frame is closed (using anynomus inner class)
          addWindowListener( new WindowAdapter() {
               public void windowClosing( WindowEvent e ) {
                    System.exit( 0 );
                    }); //end of inner class
                    public static void main( String[] args ) {
                         DemoWindow test = new DemoWindow();
                         test.setVisible( true );   }} //end of DemoWindow classWhen the program starts, the Demo window will fill � the area of the screen, and the center of the
window will be at the center of the screen. This sizing and positioning will be based on the current
screen display mode, not on hard-coded constants. The window title will be "Event-Handling
Demonstration". When the window is closed, the program will end.
The DemoPanel class will handle keyboard events using an inner class or classes. The
isFocusTraversable method will be used to allow the DemoPanel to obtain keyboard focus.
DemoPanel will collect from the keyboard all characters that are not action keys. Each time the Enter
key is pressed, DemoPanel will set the title of the Demo window equal to the characters collected since
the last time the Enter key was pressed, not including the Enter key. If the characters entered are an
integer number greater than 0, DemoPanel will set the current drawing square size (see below) equal to
this number. To set the square size, use a code structure similar to the following, where str is the
String of collected characters:
try {
squareSize = Integer.parseInt(str);
} catch (NumberFormatException xcp) {};
how do i do the second part

Answer 1

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