JRadioButton Input not responding

Question

i'm new to Java, and programming in general.I am trying an exercise where i create radio buttons which change the background colour when selected.At the moment i am using Eclipse IDE.

Eclipse is not giving me any errors and i can run the b/m program just fine, with the radiobuttons showing up and being clickable.However, the radio buttons fail to change the background colour when i select them. I would appreciate any answers and pointers i can get.

Thanks!

    import java.awt.*;
    import java.awt.event.*;
    import javax.swing.*;
    import javax.swing.event.*;


    public class Gui{
    //Declares Variables
    JRadioButton red=new JRadioButton("red");
    JRadioButton blue=new JRadioButton("blue");
    JRadioButton yellow=new JRadioButton("yellow");
    ButtonGroup group = new ButtonGroup();
    //Constructor
    public Gui(){
        //Sets title
        super("RadioButton Exercise");
        //Sets layout as default
        setLayout(new FlowLayout());
        //Adds the JRadioButtons
        add(red);
        add(blue);
        add(yellow);
        //Groups the variables
        group.add(red);
        group.add(blue);
        group.add(yellow);
        //Creates HandlerClass object
        HandlerClass handler = new HandlerClass();
        //When buttons are clicked, HandlerClass is called
        red.addItemListener(handler);
        blue.addItemListener(handler);
        yellow.addItemListener(handler);


    }

    public class HandlerClass implements ItemListener{
        public void itemStateChanged(ItemEvent x){
            if(x.getSource()==red){
                setBackground(Color.RED);
            }
            else if(x.getSource()==blue){
                setBackground(Color.BLUE);
            }
            else{
                setBackground(Color.YELLOW);
            }
        }
    }



    }

for better help sooner post an [SSCCE](http://sscce.org/), with your `main class`, otherwise talking about `JComponents` are added to the `JFrame` directly, then to use `getContentPane.setBackground(...)` — mKorbel, Apr 05 '13 at 13:39

Reimeus · Accepted Answer · 2013-04-05T14:06:12.767

2

Assuming that you meant

public class Gui extends JFrame {

It's not that the JRadioButton that is not responding, the problem is that setBackGround is being called on the frame directly, rather than it's visible component, i.e. the ContentPane. You can use:

getContentPane().setBackground(Color.RED);

edited Apr 05 '13 at 14:06

answered Apr 05 '13 at 13:37

Reimeus

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but I'm miss there extend JFrame, maybe about how is possible to coding another woodoo in Java – mKorbel Apr 05 '13 at 13:43
paste error, can be the only logical explanation, given the `super("...")` call – Reimeus Apr 05 '13 at 13:44
`Eclipse is not giving me any errors and i can run the b/m program just fine, with the radiobuttons showing up and being clickable.However, the radio buttons fail to change the background colour when i select them.` talking about you are right, but nobody knows, we aren't expert to Star Wars .... – mKorbel Apr 05 '13 at 13:46
Doesn't compile without adding this – Reimeus Apr 05 '13 at 13:46
yes you miss there implements ItemListener extends JFrame, then could be works, OP is l*** – mKorbel Apr 05 '13 at 13:48
Reimeus was right, it started working with getContentPane.setBackground(Color.RED); Thanks a bunch for the help guys! @mKorbel, ill keep the SSCCE in mind next time;) – Kenneth .J Apr 05 '13 at 15:29

score 0 · Answer 2 · answered Apr 05 '13 at 13:52

You have conditions like x.getSource()==red. It does not compare objects; it compares object references. So even if two different object references point to the same object such expression will yield False.

If you want to compare objects you need to use equals method. For equal to produce meaningful result the two objects should be of the same type.

I suggest the following: (JradioButton)x.getSource().equals(red);

JRadioButton Input not responding

2 Answers2