Why does setSelected on JCheckBox lose effect?

Question

Can someone explain to me why I lost the selection (set by setSelected()) for JCheckBox when I put the JOptionPane into the Item

Answer 1

It is a known bug as acknowledged by Oracle Bug ID:6924233 The JOptionPane apparently causes another event to be generated with a check box value = false.

The recommended fix is to instantiate the JOptionPane using invokeLater.

Submitted On 09-MAR-2010

The change is in the BasicButtonListener -  Method focusLost()

In 1.6.0_18 it is

       ...
       ButtonModel model = b.getModel();
       model.setPressed(false);
       model.setArmed(false);

in 1.6.0_10 it was

       ...
       ButtonModel model = b.getModel();
       model.setArmed(false);
       model.setPressed(false);

(The order of the statements changed)

And a setPressed(false) with armed==true leads on an ToggleButton like 
the JCheckBox to a change of the selection (see ToggleButtonModel)