4

Here is my question.Lets say that somebody made a checkbox in java and he is using it in a GUI interface so that the user can select a variety of options.Then the programmer wants to create a button inside the checkbox so that when the user checks that button all the other options will be checked as well.And when he unchecks that button of course all the other buttons will be unchecked.How is that possible in java?

Example : 

o1 = new JCheckBox("Option 1");
o2 = new JCheckBox("Option 2");
o3 = new JCheckBox("Option 3");
All = new JCheckBox("All");

.....

CheckBoxHandler listener = new CheckBoxHandler();
All.addItemListener(listener);

......

Lets assume that the following code is on a class that was created as it implements ItemListener

public class CheckBoxHandler implements ItemListener
{
 public void itemStateChanged(ItemEvent e)
  {
    if (e.getSource()==All)
      if (e.getStateChange()==ItemEvent.SELECTED)
        {
          .... <------ (!!!)Here inside I am currently stack and I do not know how to 
          add the correct code in order to have all the other buttons checked.
        }
   }
 }

Any help provided is really appreciated :)

mKorbel
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Bestial Wraith
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  • One solution is to hold a `List`, add to it every `JCheckBox` you add, iterate on it and `setSelected(true)` on the elements. – Maroun Jun 24 '13 at 14:33

3 Answers3

2

You can call setSelected() on the JCheckbox (inherited from AbstractButton):

...
o1.setSelected(true); // or false
...

As @Juvanis mentions, instead of having three different references for o1, o2 and o3, you should use an array. Then, you can do something like

for( JCheckbox cb : checkboxes ) {
    cb.setSelected(true);
}

to set all checkboxes in the array as checked.

Andreas Fester
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2

Make use of the concept of array.

JCheckBox[] checkboxes = new JCheckBox[10];

When you need to apply some operation to all checkboxes, iterate over the array:

for( JCheckbox cb : checkboxes )
   cb.doStuff();
Juvanis
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2

CheckBoxes can have ActionListeners. Why not add an ActionListener to all the checkboxes that then checks if the one selected is checked or not and calls setSelected(true) or setSelected(false) on each one?

If you have a known small number of checkboxes (such as the 3 you talked about), you may just want to hard code it. However, if you need to make it modular or have a large number of check boxes, you can always store them in a data structure (as Juvanis said, an array would probably work nicely) and loop it

Daniel
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  • Hard coding it is a bad idea since he might change his mind and add 5 more checkboxes someday.. I always prefer the second suggestion you made. – Maroun Jun 24 '13 at 14:41
  • @MarounMaroun ditto but sometimes (especially for an assignment or a dumb little self project) you just want it to work – Daniel Jun 24 '13 at 14:45
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    If you want to be a good programmer, you should get used to good approaches from the beginning :D – Maroun Jun 24 '13 at 14:46