If you mean that you want to just select  one of them,,you should put the same name for all your 3 radio button like this:
<input type="radio" name="test" value="red">
<input type="radio" name="test" value="blue">
<input type="radio" name="test" value="green">

You need to create a ButtonGroup object and then add all radio buttons that work
together as one group!

ButtonGroup group = new ButtonGroup();
group.add(radio1);
group.add(radio2);
...

It then works fine!

If you want to select  one of your JRadioButton you need toadd them in one group.ButtonGroup class will do it for you. Look at the sample:
public class RadioButtonDemo{
JFrame f = new JFrame();
Container c = f.getContentPane();
c.setLayout();
//Instances RaidioButtons
JRadioButton btn1 = new JRadioButon();
JRadioButton btn2 = new JRadioButon();
JRadioButton btn3 = new JRadioButon();

ButtonGroup group = new ButtonGroup();
group.add(btn1);
group.add(btn2);
group.add(btn3);

c. add(btn1);
c. add(btn2);
c. add(btn3);

f.pack();
f.setVisible(true);


}

You need to use the ButtonGroup class. See here: java.sun.com/.../ButtonGroup.html

1. Create an instance of ButtonGroup.
2. Create instances of JRadioButton.
3. Add each JRadioButton instance to the ButtonGroup instance.

// Create the button group.
bg = new ButtonGroup();
// Create the radio buttons. Select the first one.
jrbFrench = new JRadioButton("French", true);
jrbGerman = new JRadioButton("German");
jrbChinese = new JRadioButton("Chinese");
// Add the radio buttons to the group.
bg.add(jrbFrench);
bg.add(jrbGerman);
bg.add(jrbChinese);

You should declare a ButtonGroup and then in initialize() method or your JRadioButton decalation method
you should add your JradioButton to the declared ButtonGroup.
So , you will have something like this :


ButtonGroup btngrp = new ButtonGroup();

....

btnRepayment .add(jrb1);

You have to create a "javax.swing.ButtonGroup" and add your radio buttons to it.

Hope it will help you.

You should use ButtonGroup to group your radio buttons.
In below example if jrb1 and jrb2 and jrb3 are JRadioButton instances so group make them as a group so you can just select  one of them.

ButtonGroup group = new ButtonGroup();
group.add(jrb1);
group.add(jrb2);
group.add(jrb3);

ButtonGroup Class , like this

JRadioButton birdButton = new JRadioButton("bird");
JRadioButton catButton = new JRadioButton("cat");
ButtonGroup group = new ButtonGroup();
group.add(birdButton);
group.add(catButton);
birdButton.setSelected(true);

at the same time just one of the catButton or birdButton can be selected

You can overcome this problem  using the following code.
buttonGroup1 = new javax.swing.ButtonGroup();
jRadioButton1 = new javax.swing.JRadioButton();
jRadioButton2 = new javax.swing.JRadioButton();
jRadioButton3 = new javax.swing.JRadioButton();
buttonGroup1.add(jRadioButton1);
buttonGroup1.add(jRadioButton2);
buttonGroup1.add(jRadioButton3);
this will create a group where you can select  only one of radio button