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();

    }

}
}

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.