Java Netbeans - Key Listener doesn't work

Java Netbeans - Key Listener doesn't work

After searching on internet why it's happening and trying to change my
code in any possible way that I know, it still doesn't work. Basiclly i
want to make my JFrame appear when shift is hold. That's my code:
public DesktopMenu() {
initComponents();
setFocusable(true);
//Listening to the mouse movement to change position of the window
this.addMouseMotionListener(new MouseAdapter(){
@Override
public void mouseMoved(MouseEvent e){
xPos = e.getX();
yPos = e.getY();
setLocation((e.getXOnScreen()-xPos),(e.getYOnScreen()-yPos));
}
});
//This should listen to the key, when it's pressed window just appear.
this.addKeyListener(new KeyListener(){
@Override
public void keyPressed(KeyEvent e){
if(e.getKeyCode() == KeyEvent.VK_SHIFT){
setVisible(true);
}else{
setVisible(false);
}
};
@Override
public void keyReleased(KeyEvent e) {
}
@Override
public void keyTyped(KeyEvent e) {
}
});
}
I run the window in standard Java Class with new
DesktopMenu().setVisible(false); 'cause i want to make it just appear when
SHIFT is pressed and hold. Thanks in advance.