Using JRadioButtons in Applets
This is adapted version of the preceding applet with a group of JRadioButtons instead of four individual buttons. We added the buttons to a ButtonGroup and to a JPanel and set the button selected initially with setSelected. The next page shows selection of items with a JComboBox
The code follows this screenshot of the applet in action.

JRadioButton applet (400 x 270) in action
namespace jradiobutton_demo; interface uses java.util, java.applet.*, java.awt.*, javax.swing; type JRadioButtonDemo = public class(Applet, ActionListener) private rbtnAppend, rbtnReplace, rbtnInsert, rbtnCopy : JRadioButton; txtNew : TextField; taEdit, taCopy : JTextArea; initText : String := 'This is the starting text to modify by pressing the buttons.'; lblInstruction : Label; radioPanel : JPanel; rgroup : ButtonGroup; public method init; override; method actionPerformed(e : ActionEvent); end; implementation method JRadioButtonDemo.init; begin Background := Color.green.darker; lblInstruction := new Label('Enter the text to append, insert, or replace with.'); add(lblInstruction); txtNew := new TextField('', 40); add(txtNew); radioPanel := new JPanel(new GridLayout(0, 1)); rgroup := new ButtonGroup; rbtnAppend := new JRadioButton('Append'); rbtnReplace := new JRadioButton('Replace selected text'); rbtnInsert := new JRadioButton('Insert at cursor position'); rbtnCopy := new JRadioButton('Copy to lower TextArea'); rgroup.add(rbtnAppend); rgroup.add(rbtnReplace); rgroup.add(rbtnInsert); rgroup.add(rbtnCopy); radioPanel.add(rbtnAppend); radioPanel.add(rbtnReplace); radioPanel.add(rbtnInsert); radioPanel.add(rbtnCopy); rbtnAppend.addActionListener(self); rbtnReplace.addActionListener(self); rbtnInsert.addActionListener(self); rbtnCopy.addActionListener(self); rbtnAppend.setselected(true); taEdit := new JTextArea(initText, 5, 20); taCopy := new JTextArea('', 5, 20); taEdit.setLineWrap(true); taCopy.setLineWrap(true); taEdit.setWrapStyleWord(true); taCopy.setWrapStyleWord(true); add(taEdit); add(radioPanel); add(taCopy); taEdit.setForeground (Color.blue.brighter); taCopy.setForeground (Color.red); end; method JRadioButtonDemo.actionPerformed(e : ActionEvent); begin if e.getSource = rbtnAppend then taEdit.append(txtNew.getText); if e.getSource = rbtnReplace then taEdit.replaceRange(txtNew.getText, taEdit.getSelectionStart, taEdit.getSelectionEnd); if e.getSource = rbtnInsert then taEdit.insert(txtNew.getText, taEdit.getCaretPosition); if e.getSource = rbtnCopy then taCopy.setText(taEdit.getText); end; end.