填空题

本题的功能是监听键盘键的敲击，并显示在窗口中。
import javax. swing. * ;
import java. awt. * ;
import java. awt. event. * ;
public class java3 extends JFrame extends KeyListener

private String line1="", line2="";
private String line3="";
private JTextArea textArea;
public java3()

super("java3");
textArea=new JTextArea(10,15);
textArea, setText("Press any key on the key-board... ");
textArea, setEnabled(false);
addKeyListener(this);
getContentPane(). add(textArea);
setSize(350,100);
show();

public void keyPressed(KeyEvent e)

lind="Key pressed:"+e. getKeyText(e. getKeyCode());
setLines2and3(e);

public void keyReleased(KeyEvent e)

line1="Key released:"+e. getKeyText(e. getKeyCode());
setLines2and3(e);

public void keyTyped(KeyEvent e)

Lind="Key typed:"+e. getKeychar();
setLines2and3(e);

private void setLines2and3(KeyEvent e)

line2="This key is"+(e. isActionKey()"":"not")+"an action key";
String temp=e. getKeyModifiersText(e. getModifiers());
line3="Modifier keys pressed:"+(temp. equals() "none": temp);
textArea. setText(line1+"\n"+line2+"\n"+line3+"\n");

public static void main(String args[])

java3 app=new java8();
addWindowListener(new Windowadapterl()

public void windowClosing(WindowEvent e)

System. exit(0);

);