Step by step simple Java GUI example (ComboBox & ListBox)

step1.java

        ....
        private DefaultComboBoxModel ganjil = new DefaultComboBoxModel();
	private JComboBox cmb = new JComboBox(ganjil);

	private DefaultListModel genap = new DefaultListModel();
	private JList list = new JList(genap);
        ....

step2.java

        ....
	private void btnTambahClick(ActionEvent evt){
		Integer p;
		try
		{
			p = Integer.parseInt(tBil.getText());
			if (p % 2 == 0)
			{
				genap.insertElementAt(p.toString(),0);
			}else{
				ganjil.insertElementAt(p.toString(),0);
			}
		}
		catch (Exception e)
		{
			System.out.println(e);
			JOptionPane.showMessageDialog(null, 
                                    e.toString(),
                                    "Error", 
                                    JOptionPane.ERROR_MESSAGE);
		}
	}
        ....