java swing redrawing buttons -

i pasting following code here. puzzled at: why there no jbuttons added jpanel, though event correctly listened , responded.

thank help.

import java.awt.component;  import java.awt.toolkit; import java.awt.event.keyadapter;  import java.awt.event.keyevent;  import javax.swing.boxlayout; import javax.swing.grouplayout; import javax.swing.jbutton; import javax.swing.jframe; import javax.swing.jpanel; import javax.swing.jtextfield;   public class panelcontrolbuttons extends jframe {     private jpanel jpanel1 = new jpanel();     private jpanel jpanel2 = new jpanel();     private jpanel jpanel = new jpanel();     private jtextfield jtf = new jtextfield(20);      public panelcontrolbuttons() {         setsize(400, 300);         getcontentpane().add(jpanel);         jpanel.setlayout(new boxlayout(jpanel, boxlayout.x_axis));         jpanel2.setlayout(new boxlayout(jpanel2, boxlayout.x_axis));         jpanel.add(jpanel1);         jpanel.add(jpanel2);         jpanel2.add(new jbutton("abc"));         (int = 0; < 3; i++) {             jpanel2.add(new jbutton(integer.tostring(i)));         }         jpanel1.add(jtf);         jpanel2.setlayout(new boxlayout(jpanel2, boxlayout.x_axis));         jtf.addkeylistener(new keyadapter() {                 public void keypressed(keyevent e) {                     int key = e.getkeycode();                     if (key == keyevent.vk_enter) {                         system.out.println("enter pressed");                         int n = integer.parseint(jtf.gettext());                         system.out.println(n);                         (int = 0; < n; i++) {                             jpanel2.add(new jbutton(integer.tostring(i)));                         }                     }                 }             });         setvisible(true);     }      public static void main(string[] args) {         panelcontrolbuttons panelcontrolbuttons = new panelcontrolbuttons();     } } 

anytime add new component on container, should call revalidate , repaint:

           (int = 0; < n; i++) {               jpanel2.add(new jbutton(integer.tostring(i)));            }            jpanel2.revalidate();            jpanel2.repaint(); 

the first tell layout managers thing, second have java paint manager repaint container redraw dirty bits.

edit
revalidate , repaint methods moved out of loop per mkorbel's excellent recommendation.