how i boldly supplement panels panels during runtime java?

i'm perplexing java again (it's few years). i never unequivocally any gui coding java. i've controlling netbeans started this.

when controlling winforms c# during work i usercontrols build tools ui supplement forms dynamically.

i've perplexing jpanels usercontrols c#. i combined jpanel form called blurbeditor. few rudimentary controls it. i am perplexing supplement another quarrel during run symbol event.

here formula i guess work:

mainpanel.add(new blurbeditor());
mainpanel.revalidate();
//i've also attempted illusory combinations too
//mainpanel.repaint();
//mainpanel.validate();

this unfortunately working. am i doing wrong?