Typically, some object associated with the selected radio button is required. It is not necessarily a String representing the button's label. It could be an Integer containing the button's index or an object of more complicated type T. You could fill and use a Map<ButtonModel, T> as Tom Hawtin suggested, but I propose to extend the model and place the objects there. Here's an improved ButtonGroup that uses this approach.
import javax.swing.*;
@SuppressWarnings("serial")
public class SmartButtonGroup<T> extends ButtonGroup {
@Override
public void add(AbstractButton b) {
throw new UnsupportedOperationException("No object supplied");
}
public void add(JRadioButton button, T attachedObject) {
ExtendedModel<T> model = new ExtendedModel<>(attachedObject);
model.setSelected(button.isSelected());
button.setModel(model);
super.add(button);
}
@SuppressWarnings("unchecked")
public T getSelectedObject() {
ButtonModel selModel = getSelection();
return selModel != null ? ((ExtendedModel<T>)selModel).obj : null;
}
public static class ExtendedModel<T> extends javax.swing.JToggleButton.ToggleButtonModel {
public T obj;
private ExtendedModel(T object) {
obj = object;
}
}
}
You can use this utility class instead of ButtonGroup. Create an object of this class and add buttons along with associated objects to it. For example,
SmartButtonGroup<Integer> group = new SmartButtonGroup<>();
JPanel panel = new JPanel();
for (int i = 1; i <= 5; i++) {
JRadioButton button = new JRadioButton("Button #" + i, i == 3); // select the 3rd button
group.add(button, i);
panel.add(button);
}
After this, you can get the object associated with the currently selected button anytime you need by simply calling getSelectedObject(), like this:
int selectedButtonIndex = group.getSelectedObject();
In case you need just the buttons themselves, you can use the next non-generic class instead.
import javax.swing.JRadioButton;
@SuppressWarnings("serial")
public class RadioButtonGroup extends SmartButtonGroup<JRadioButton> {
public void add(JRadioButton button) {
super.add(button, button);
}
@Override
public void add(JRadioButton button, JRadioButton attachedObject) {
throw new UnsupportedOperationException("Use the short form of addition instead");
}
public JRadioButton getSelectedButton() {
return getSelectedObject();
}
}
