public void actionPerformed(ActionEvent e) {
   Configuration.getInstance()
       .setClassProperty(VariableNameDialog.class, "variableName", jt.getText());
   dispose();
 }
 public VariableNameDialog(CrossoverGUI graphGUI) {
   this(
       graphGUI,
       Configuration.getInstance().getClassProperty(VariableNameDialog.class, "variableName", ""));
 }