title: I can''t figure out how to use the comboBox to remove radiobuttons
body: <pre><code>import java.awt.EventQueue;
  import javax.swing.JFrame;
  import javax.swing.JPanel;
  import javax.swing.border.EmptyBorder;
  import javax.swing.ButtonGroup;
  import javax.swing.JLabel;
  import javax.swing.JDesktopPane;
  import javax.swing.JRadioButton;
  import javax.swing.JComboBox;
  import java.awt.GridBagLayout;
  import java.awt.GridBagConstraints;
  import java.awt.Insets;
  import java.awt.Color;
  import java.awt.event.ActionEvent;
  import java.awt.event.ActionListener;
  
  @SuppressWarnings("serial")
  public class Calendar1 extends JFrame implements ActionListener {
      private JPanel contentPane;
      String[] Months = { "January", "February", "March", "April", "May", "June",
              "July", "August", "September", "October", "November", "December" };
      JDesktopPane desktopPane;
      ButtonGroup bG = new ButtonGroup();
      JRadioButton radioButton, rdbtnNewRadioButton, radioButton_1,
              radioButton_2, radioButton_3, radioButton_4, radioButton_5,
              radioButton_6, radioButton_7, radioButton_8, radioButton_9,
              radioButton_10, radioButton_11, radioButton_12, radioButton_13,
              radioButton_14, radioButton_15, radioButton_16, radioButton_17,
              radioButton_18, radioButton_19, radioButton_20, radioButton_21,
              radioButton_22, radioButton_23, radioButton_24, radioButton_25,
              radioButton_26, radioButton_27, radioButton_28, radioButton_29;
  
  /**
   * Launch the application.
   */
  
  public static void main(String[] args) {
      EventQueue.invokeLater(new Runnable() {
          public void run() {
              try {
                  Calendar1 frame = new Calendar1();
                  frame.setVisible(true);
              } catch (Exception e) {
                  e.printStackTrace();
              }
          }
      });
  }
  
  /**
   * Create the frame.
   */
  @SuppressWarnings("unchecked")
  public Calendar1() {
      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      setBounds(100, 100, 521, 300);
      contentPane = new JPanel();
      contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
      setContentPane(contentPane);
      contentPane.setLayout(null);
  
      JComboBox comboBox = new JComboBox(Months);
      comboBox.setBounds(28, 16, 132, 27);
      contentPane.add(comboBox);
      comboBox.setSelectedIndex(0);
      comboBox.addActionListener(this);
  
      JLabel label = new JLabel("2014");
      label.setBounds(350, 20, 61, 16);
      contentPane.add(label);
  
      desktopPane = new JDesktopPane();
      desktopPane.setBackground(new Color(30, 144, 255));
      desktopPane.setBounds(0, 63, 495, 188);
      contentPane.add(desktopPane);
  
      GridBagLayout gbl_desktopPane = new GridBagLayout();
      gbl_desktopPane.columnWidths = new int[] { 0, 0, 0, 0, 0, 0, 0, 0, 0,
              0, 0, 0, 0, 0, 0, 0, 0 };
      gbl_desktopPane.rowHeights = new int[] { 0, 0, 0, 0, 0, 0, 0, 0 };
      gbl_desktopPane.columnWeights = new double[] { 0.0, 0.0, 0.0, 0.0, 0.0,
              0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
              Double.MIN_VALUE };
      gbl_desktopPane.rowWeights = new double[] { 0.0, 0.0, 0.0, 0.0, 0.0,
              0.0, 0.0, Double.MIN_VALUE };
      desktopPane.setLayout(gbl_desktopPane);
  
      // JLabel lblSun = new JLabel("Sun");
      // lblSun.setForeground(Color.RED);
      //
      // GridBagConstraints gbc_lblSun = new GridBagConstraints();
      // gbc_lblSun.insets = new Insets(0, 0, 5, 5);
      // gbc_lblSun.gridx = 2;
      // gbc_lblSun.gridy = 0;
      // desktopPane.add(lblSun, gbc_lblSun);
      //
      // JLabel lblMon = new JLabel("Mon");
      // GridBagConstraints gbc_lblMon = new GridBagConstraints();
      // gbc_lblMon.insets = new Insets(0, 0, 5, 5);
      // gbc_lblMon.gridx = 4;
      // gbc_lblMon.gridy = 0;
      // desktopPane.add(lblMon, gbc_lblMon);
      //
      // JLabel lblTues = new JLabel("Tues");
      // GridBagConstraints gbc_lblTues = new GridBagConstraints();
      // gbc_lblTues.insets = new Insets(0, 0, 5, 5);
      // gbc_lblTues.gridx = 6;
      // gbc_lblTues.gridy = 0;
      // desktopPane.add(lblTues, gbc_lblTues);
      //
      // JLabel lblWed = new JLabel("Wed");
      // GridBagConstraints gbc_lblWed = new GridBagConstraints();
      // gbc_lblWed.insets = new Insets(0, 0, 5, 5);
      // gbc_lblWed.gridx = 8;
      // gbc_lblWed.gridy = 0;
      // desktopPane.add(lblWed, gbc_lblWed);
      //
      // JLabel lblThurs = new JLabel("Thurs");
      // GridBagConstraints gbc_lblThurs = new GridBagConstraints();
      // gbc_lblThurs.insets = new Insets(0, 0, 5, 5);
      // gbc_lblThurs.gridx = 10;
      // gbc_lblThurs.gridy = 0;
      // desktopPane.add(lblThurs, gbc_lblThurs);
      //
      // JLabel lblFri = new JLabel("Friday");
      // GridBagConstraints gbc_lblFri = new GridBagConstraints();
      // gbc_lblFri.insets = new Insets(0, 0, 5, 5);
      // gbc_lblFri.gridx = 12;
      // gbc_lblFri.gridy = 0;
      // desktopPane.add(lblFri, gbc_lblFri);
      //
      // JLabel lblSat = new JLabel("Sat");
      // lblSat.setForeground(Color.RED);
      // GridBagConstraints gbc_lblSat = new GridBagConstraints();
      // gbc_lblSat.insets = new Insets(0, 0, 5, 5);
      // gbc_lblSat.gridx = 14;
      // gbc_lblSat.gridy = 0;
      // desktopPane.add(lblSat, gbc_lblSat);
  
      radioButton = new JRadioButton("1");
      GridBagConstraints gbc_radioButton = new GridBagConstraints();
      gbc_radioButton.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton.gridx = 8;
      gbc_radioButton.gridy = 1;
      desktopPane.add(radioButton, gbc_radioButton);
      bG.add(radioButton);
  
      rdbtnNewRadioButton = new JRadioButton("2");
      GridBagConstraints gbc_rdbtnNewRadioButton = new GridBagConstraints();
      gbc_rdbtnNewRadioButton.insets = new Insets(0, 0, 5, 5);
      gbc_rdbtnNewRadioButton.gridx = 10;
      gbc_rdbtnNewRadioButton.gridy = 1;
      desktopPane.add(rdbtnNewRadioButton, gbc_rdbtnNewRadioButton);
      bG.add(rdbtnNewRadioButton);
  
      radioButton_1 = new JRadioButton("3");
      GridBagConstraints gbc_radioButton_1 = new GridBagConstraints();
      gbc_radioButton_1.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_1.gridx = 12;
      gbc_radioButton_1.gridy = 1;
      desktopPane.add(radioButton_1, gbc_radioButton_1);
      bG.add(radioButton_1);
  
      radioButton_2 = new JRadioButton("4");
      GridBagConstraints gbc_radioButton_2 = new GridBagConstraints();
      gbc_radioButton_2.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_2.gridx = 14;
      gbc_radioButton_2.gridy = 1;
      desktopPane.add(radioButton_2, gbc_radioButton_2);
      bG.add(radioButton_2);
  
      radioButton_3 = new JRadioButton("5");
      GridBagConstraints gbc_radioButton_3 = new GridBagConstraints();
      gbc_radioButton_3.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_3.gridx = 2;
      gbc_radioButton_3.gridy = 2;
      desktopPane.add(radioButton_3, gbc_radioButton_3);
      bG.add(radioButton_3);
  
      radioButton_4 = new JRadioButton("6");
      GridBagConstraints gbc_radioButton_4 = new GridBagConstraints();
      gbc_radioButton_4.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_4.gridx = 4;
      gbc_radioButton_4.gridy = 2;
      desktopPane.add(radioButton_4, gbc_radioButton_4);
      bG.add(radioButton_4);
  
      radioButton_5 = new JRadioButton("7");
      GridBagConstraints gbc_radioButton_5 = new GridBagConstraints();
      gbc_radioButton_5.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_5.gridx = 6;
      gbc_radioButton_5.gridy = 2;
      desktopPane.add(radioButton_5, gbc_radioButton_5);
      bG.add(radioButton_5);
  
      radioButton_6 = new JRadioButton("8");
      GridBagConstraints gbc_radioButton_6 = new GridBagConstraints();
      gbc_radioButton_6.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_6.gridx = 8;
      gbc_radioButton_6.gridy = 2;
      desktopPane.add(radioButton_6, gbc_radioButton_6);
      bG.add(radioButton_6);
  
      radioButton_7 = new JRadioButton("9");
      GridBagConstraints gbc_radioButton_7 = new GridBagConstraints();
      gbc_radioButton_7.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_7.gridx = 10;
      gbc_radioButton_7.gridy = 2;
      desktopPane.add(radioButton_7, gbc_radioButton_7);
      bG.add(radioButton_7);
  
      radioButton_8 = new JRadioButton("10");
      GridBagConstraints gbc_radioButton_8 = new GridBagConstraints();
      gbc_radioButton_8.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_8.gridx = 12;
      gbc_radioButton_8.gridy = 2;
      desktopPane.add(radioButton_8, gbc_radioButton_8);
      bG.add(radioButton_8);
  
      radioButton_9 = new JRadioButton("11");
      GridBagConstraints gbc_radioButton_9 = new GridBagConstraints();
      gbc_radioButton_9.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_9.gridx = 14;
      gbc_radioButton_9.gridy = 2;
      desktopPane.add(radioButton_9, gbc_radioButton_9);
      bG.add(radioButton_9);
  
      radioButton_10 = new JRadioButton("12");
      GridBagConstraints gbc_radioButton_10 = new GridBagConstraints();
      gbc_radioButton_10.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_10.gridx = 2;
      gbc_radioButton_10.gridy = 3;
      desktopPane.add(radioButton_10, gbc_radioButton_10);
      bG.add(radioButton_10);
  
      radioButton_11 = new JRadioButton("13");
      GridBagConstraints gbc_radioButton_11 = new GridBagConstraints();
      gbc_radioButton_11.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_11.gridx = 4;
      gbc_radioButton_11.gridy = 3;
      desktopPane.add(radioButton_11, gbc_radioButton_11);
      bG.add(radioButton_11);
  
      radioButton_12 = new JRadioButton("14");
      GridBagConstraints gbc_radioButton_12 = new GridBagConstraints();
      gbc_radioButton_12.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_12.gridx = 6;
      gbc_radioButton_12.gridy = 3;
      desktopPane.add(radioButton_12, gbc_radioButton_12);
      bG.add(radioButton_12);
  
      radioButton_13 = new JRadioButton("15");
      GridBagConstraints gbc_radioButton_13 = new GridBagConstraints();
      gbc_radioButton_13.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_13.gridx = 8;
      gbc_radioButton_13.gridy = 3;
      desktopPane.add(radioButton_13, gbc_radioButton_13);
      bG.add(radioButton_13);
  
      radioButton_14 = new JRadioButton("16");
      GridBagConstraints gbc_radioButton_14 = new GridBagConstraints();
      gbc_radioButton_14.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_14.gridx = 10;
      gbc_radioButton_14.gridy = 3;
      desktopPane.add(radioButton_14, gbc_radioButton_14);
      bG.add(radioButton_14);
  
      radioButton_15 = new JRadioButton("17");
      GridBagConstraints gbc_radioButton_15 = new GridBagConstraints();
      gbc_radioButton_15.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_15.gridx = 12;
      gbc_radioButton_15.gridy = 3;
      desktopPane.add(radioButton_15, gbc_radioButton_15);
      bG.add(radioButton_15);
  
      radioButton_16 = new JRadioButton("18");
      GridBagConstraints gbc_radioButton_16 = new GridBagConstraints();
      gbc_radioButton_16.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_16.gridx = 14;
      gbc_radioButton_16.gridy = 3;
      desktopPane.add(radioButton_16, gbc_radioButton_16);
      bG.add(radioButton_16);
  
      radioButton_17 = new JRadioButton("19");
      GridBagConstraints gbc_radioButton_17 = new GridBagConstraints();
      gbc_radioButton_17.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_17.gridx = 2;
      gbc_radioButton_17.gridy = 4;
      desktopPane.add(radioButton_17, gbc_radioButton_17);
      bG.add(radioButton_17);
  
      radioButton_18 = new JRadioButton("20");
      GridBagConstraints gbc_radioButton_18 = new GridBagConstraints();
      gbc_radioButton_18.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_18.gridx = 4;
      gbc_radioButton_18.gridy = 4;
      desktopPane.add(radioButton_18, gbc_radioButton_18);
      bG.add(radioButton_18);
  
      radioButton_19 = new JRadioButton("21");
      GridBagConstraints gbc_radioButton_19 = new GridBagConstraints();
      gbc_radioButton_19.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_19.gridx = 6;
      gbc_radioButton_19.gridy = 4;
      desktopPane.add(radioButton_19, gbc_radioButton_19);
      bG.add(radioButton_19);
  
      radioButton_20 = new JRadioButton("22");
      GridBagConstraints gbc_radioButton_20 = new GridBagConstraints();
      gbc_radioButton_20.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_20.gridx = 8;
      gbc_radioButton_20.gridy = 4;
      desktopPane.add(radioButton_20, gbc_radioButton_20);
      bG.add(radioButton_20);
  
      radioButton_21 = new JRadioButton("23");
      GridBagConstraints gbc_radioButton_21 = new GridBagConstraints();
      gbc_radioButton_21.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_21.gridx = 10;
      gbc_radioButton_21.gridy = 4;
      desktopPane.add(radioButton_21, gbc_radioButton_21);
      bG.add(radioButton_21);
  
      radioButton_22 = new JRadioButton("24");
      GridBagConstraints gbc_radioButton_22 = new GridBagConstraints();
      gbc_radioButton_22.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_22.gridx = 12;
      gbc_radioButton_22.gridy = 4;
      desktopPane.add(radioButton_22, gbc_radioButton_22);
      bG.add(radioButton_22);
  
      radioButton_23 = new JRadioButton("25");
      GridBagConstraints gbc_radioButton_23 = new GridBagConstraints();
      gbc_radioButton_23.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_23.gridx = 14;
      gbc_radioButton_23.gridy = 4;
      desktopPane.add(radioButton_23, gbc_radioButton_23);
      bG.add(radioButton_23);
  
      radioButton_24 = new JRadioButton("26");
      GridBagConstraints gbc_radioButton_24 = new GridBagConstraints();
      gbc_radioButton_24.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_24.gridx = 2;
      gbc_radioButton_24.gridy = 5;
      desktopPane.add(radioButton_24, gbc_radioButton_24);
      bG.add(radioButton_24);
  
      radioButton_25 = new JRadioButton("27");
      GridBagConstraints gbc_radioButton_25 = new GridBagConstraints();
      gbc_radioButton_25.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_25.gridx = 4;
      gbc_radioButton_25.gridy = 5;
      desktopPane.add(radioButton_25, gbc_radioButton_25);
      bG.add(radioButton_25);
  
      radioButton_26 = new JRadioButton("28");
      GridBagConstraints gbc_radioButton_26 = new GridBagConstraints();
      gbc_radioButton_26.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_26.gridx = 6;
      gbc_radioButton_26.gridy = 5;
      desktopPane.add(radioButton_26, gbc_radioButton_26);
      bG.add(radioButton_26);
  
      radioButton_27 = new JRadioButton("29");
      GridBagConstraints gbc_radioButton_27 = new GridBagConstraints();
      gbc_radioButton_27.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_27.gridx = 8;
      gbc_radioButton_27.gridy = 5;
      desktopPane.add(radioButton_27, gbc_radioButton_27);
      bG.add(radioButton_27);
  
      radioButton_28 = new JRadioButton("30");
      GridBagConstraints gbc_radioButton_28 = new GridBagConstraints();
      gbc_radioButton_28.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_28.gridx = 10;
      gbc_radioButton_28.gridy = 5;
      desktopPane.add(radioButton_28, gbc_radioButton_28);
      bG.add(radioButton_28);
  
      radioButton_29 = new JRadioButton("31");
      GridBagConstraints gbc_radioButton_29 = new GridBagConstraints();
      gbc_radioButton_29.insets = new Insets(0, 0, 5, 5);
      gbc_radioButton_29.gridx = 12;
      gbc_radioButton_29.gridy = 5;
      desktopPane.add(radioButton_29, gbc_radioButton_29);
      bG.add(radioButton_29);
  
  }
  
  @Override
  public void actionPerformed(ActionEvent e) {
      JComboBox cb = (JComboBox) e.getSource();
      String months = (String) cb.getSelectedItem();
      if (months.equals("February")) {
          desktopPane.remove(radioButton_28);
          desktopPane.revalidate();
  
      }
  
  }
  }
  </code></pre>
  
  <p>I'm trying to use the combobox to remove radiobuttons in the actionperformed, but when I run the program, nothing happens, nor can I enable new buttons in the actionperformed. Thank you so much in advance for helping me out.</p>