java - How to add components to JFrame once it's visible without having to resize it? -

i have program have jframe jbutton in it. when user clicks jbutton, components of jframe removed, , jpanel red background added it.

when click jbutton, red jpanel not become visible unless resize jframe (i using windows 7). there way achieve want without having manually resize jframe?

here part of code using:

public class demo implements actionlistener{     public static void main(string args[]){            ...............         button.addactionlistener(this); //'button' object of jbutton class.         frame.setvisible(true); //'frame' object of jframe class.         ............     }      public void actionperformed(actionevent ae){         frame.removeallcomponents();         frame.add(panel1); //panel1 object of jpanel class red  background.          /* here problem lies.            panel1 not visible me unless manually resize jframe. */     } } 

for removing (and then, example, add new jcomponents) jcomponents jpanel or top-level containers have call, once , on end of action:

revalidate(); repaint(); 

and if resize or change jcomponents:

validate(); repaint();