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