How do I get which JRadioButton is selected from a ButtonGroup

Question

I have a swing application that includes radio buttons on a form. I have the ButtonGroup, however, looking at the available methods, I can't seem to get the name of the selected JRadioButton. Here's what I can tell so far:

• From ButtonGroup, I can perform a getSelection() to return the ButtonModel. From there, I can perform a getActionCommand, but that doesn't seem to always work. I tried different tests and got unpredictable results.

• Also from ButtonGroup, I can get an Enumeration from getElements(). However, then I would have to loop through each button just to check and see if it is the one selected.

Is there an easier way to find out which button has been selected? I'm programing this in Java 1.3.1 and swing.

Answer 1

I would just loop through your JRadioButtons and call isSelected(). If you really want to go from the ButtonGroup you can only get to the models. You could match the models to the buttons, but then if you have access to the buttons, why not use them directly?

Answer 2

You could use getSelectedObjects() of ItemSelectable (superinterface of ButtonModel) which returns the list of selected items. In case of a radio button group it can only be one or none at all.

Answer 3

jRadioOne = new javax.swing.JRadioButton();
jRadioTwo = new javax.swing.JRadioButton();
jRadioThree = new javax.swing.JRadioButton();

... then for every button:

buttonGroup1.add(jRadioOne);
jRadioOne.setText("One");
jRadioOne.setActionCommand(ONE);
jRadioOne.addActionListener(radioButtonActionListener);

...listener

ActionListener radioButtonActionListener = new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                radioButtonActionPerformed(evt);
            }
        };

...do whatever you need as response to event

protected void radioButtonActionPerformed(ActionEvent evt) {            
       System.out.println(evt.getActionCommand());
    }

Answer 4

I suggest going straight for the model approach in Swing. After you've put the component in the panel and layout manager, don't even bother keeping a specific reference to it.

If you really want the widget, then you can test each with isSelected, or maintain a Map<ButtonModel,JRadioButton>.