Updating a JFrame's Background every second

Question

Hello all,
What i want to achieve here is very simple, I have a class which extends JFrame. In my constructor, i create my GUI (background and buttons etc.), so here is my code :
//other imports goes here
public class TestBg extends JFrame implements ActionListener{
     //constructor
     public TestBg(){
          //.. other codes go in here
          //set the first background
          setContentPane(getImage());
          //create a timer which is invoked every second
          Timer timer = new Timer(1000,this);
          timer.start();
     //close constructor
     public void actionPerformed(ActionEvent e){
          //print a statement to see if method is invoked
          System.out.println("Method invoked");
          setContentPane(getImage());
}//close classlets say the method getImage() returns a JLabel, which set it to the JFrame's background.
The actionPerformed method is invoked every second, but the background isn't changing ( getImage() returns a different JLabel each time)
what extra code do i have to add ? thanks.
NOTE : I just discovered something, i think the JFrame needs to be repainted. Because whenever i resize the Frame, the background changes!, but i do not know how to 'referesh' the JFrame without resizing it.
Message was edited by:
TrAnScEnD3nT
Message was edited by:
TrAnScEnD3nT

Answer 1

That's because You add them to container that is an original content pane. Then when You call setContentPane this container is thrown away with all it's content and new "empty" container is put in that place.
I advise using a JPanel as a contentPane and don't change it on the run. Insted you can use the timer to repaint that panel with some image specified.