Auto Update JLabel on JButton Press?

Code :

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        gen = new JButton("Generate");
        add(gen);
        gen.addActionListener(new ActionListener() {
 
            public void actionPerformed(ActionEvent e)
            {
        	    Random randomGenerator = new Random();
        	    for (int idx = 1; idx <= 1; ++idx){
        	      int randomInt = randomGenerator.nextInt(999);
 
        		test = new JLabel(""+randomInt+"");
        		add(test);
 
        	    Random randomGenerator2 = new Random();
        	    for (int idx2 = 1; idx <= 1; ++idx){
        	      int randomInt2 = randomGenerator.nextInt(999);
 
        		test = new JLabel(""+randomInt2+"");
        		add(test);
 
        	    Random randomGenerator3 = new Random();
        	    for (int idx3 = 1; idx <= 1; ++idx){
        	      int randomInt3 = randomGenerator.nextInt(9999);
 
        		test = new JLabel(""+randomInt3+"");
        		add(test);
        	    }
        	    }
        	    }
 
            }});;
        };
}

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Really need Some help.

please explain what are you up to?

When i Press the button it dose not show it until i minimize and bring back up