Java coding efficiency. JRadioButton objects and ItemListener interaction

Question

I started coding in Java recently. I wanted to code a Window which contains:

• 1 Frame
• 1 Container
• 2 JPanel objects (To make sure to not confuse Panels, Container and Frame's object)
• 1 Scroll's object
• 1 JTextArea and 1 JTextField
• 1 JButtonGroup with 3 JRadioButton associated

Its purpose were like a one-man chat. Write in the TextField, submit button and print it in the TextArea appending to any previous message. Next step, I named 3 Radio Buttons "User 1", "User 2" and "User 3" On their selection they will print: user_x.GetName+(String)message;

My first try was an ActionListener. (This is a prototype):

    ActionListener updateUserTalking = new ActionListener(){
    @Override
    public void actionPerformed(ActionEvent arg0) {
        JTextField tf = textField; //New message
        JTextArea ta = textArea; //Previous message to track an history
        String str = ta.getText()+"Radio button changed"; //This should print "User_x"
        str = str+tf.setText(str+System.lineSeparator());
    }
};

My second try was an ItemListener. (This is a prototype)

    public void itemStateChanged(ItemEvent e) {
        updateSystemMessage();  

This updateSystemMessage() call this method:

    ItemListener updateSystemMessage = new ItemListener(){
    public void itemStateChanged(ItemEvent e) {
        JTextField tf = textField; //New message
        JTextArea ta = textArea; //Previous message to track an history
        String str = ta.getText()+"RadioButton changed"; //This should print "User_x"
        str = str+tf.setText(str+System.lineSeparator());
    }
};

The latest print a double message. Because the same method is shared. So when selection is changed there are two commutation so this method will be called twice. Here comes my question:

I know I can make one method for each JRadioButton istantiated. I was guessing if there was a way to make an unique method viable. Where the JRadioButton selected give its name as parameter to the ActionListener or ItemListener.

I already tried something like this:

   private void updateSystemMessage() {
    JRadioButton jrb = (JRadioButton)this.bGroup.getSelection();
    this.system =jrb.getText();
}

But it doesn't work because bGroup.getSelection() return a ButtonModel that can't be casted as (JRadioButton). Therefore is there a way like this? Or I have to code one method for each JRadioButton (Who basically do the same thing)?

Answer 1

ActionEvent.getSource() will return the JRadioButton that generated in, so you could

ActionListener updateUserTalking = new ActionListener(){
@Override
public void actionPerformed(ActionEvent arg0) {
    JTextField tf = textField; //New message
    JTextArea ta = textArea; //Previous message to track an history
    JRadioButton jrb = (JRadioButton) arg0.getSource();
    String str = ta.getText()+"Button "+jrb.getLabel();
    str = str+tf.setText(str+System.lineSeparator());
}

Or, you get call JRadioButton.setActionCommand("button1") and then use ActionEvent.getActionCommand() to pass a unique string for each button.

JRadioButton user1 = new JRadioButton("User_1");
user1.setActionCommand("User_1");

ActionListener updateUserTalking = new ActionListener(){
@Override
public void actionPerformed(ActionEvent arg0) {
    JTextField tf = textField; //New message
    JTextArea ta = textArea; //Previous message to track an history
    String cmd = arg0.getActionCommand();
    String str = ta.getText()+"Button "+cmd;
    str = str+tf.setText(str+System.lineSeparator());
}

Or, you can use the actionCommand with ButtonModel as well.

private void updateSystemMessage() {
    String actionCommand = this.bGroup.getSelection().getActionCommand();
    this.system = actionCommand;
}