Java Swing How to - Get to the last selected item and check for reselection

Question

We would like to know how to get to the last selected item and check for reselection.

Answer

/*from   w  w w  . j a  v  a  2 s . com*/
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.AbstractButton;
import javax.swing.ButtonGroup;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JRadioButton;

public class Main {
  public static void main(String args[]) {
    JFrame frame = new JFrame("Grouping Example");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    JPanel panel = new JPanel(new GridLayout(0, 1));

    ButtonGroup group = new ButtonGroup();
    JRadioButton aRadioButton = new JRadioButton("A");
    JRadioButton bRadioButton = new JRadioButton("B");

    ActionListener crustActionListener = new ActionListener() {
      String lastSelected;

      public void actionPerformed(ActionEvent actionEvent) {
        AbstractButton aButton = (AbstractButton) actionEvent.getSource();
        String label = aButton.getText();
        String msgStart;
        if (label.equals(lastSelected)) {
          msgStart = "Reselected: ";
        } else {
          msgStart = "Selected: ";
        }
        lastSelected = label;
        System.out.println(msgStart + label);
      }
    };

    panel.add(aRadioButton);
    group.add(aRadioButton);
    panel.add(bRadioButton);
    group.add(bRadioButton);

    aRadioButton.addActionListener(crustActionListener);
    bRadioButton.addActionListener(crustActionListener);

    frame.add(panel);
    frame.setSize(300, 200);
    frame.setVisible(true);
  }
}