JDialog - gettting data from j

Question

hi!
I have created class(say A) extending JInternaFrame and also I have created a class (Say B) extending JDialog. I am trying to call an instance(IB) of B from an instance(A) of A. I am setting the modal to true in the B. when I enter some data in IB I have to pass the data to IA. I could not do this. Can anyone please let me know where I am going wrong in the logical flow? I have tried using the "JDialog(Dialog owner, String title, boolean modal) " constructor as well but this gives a class caste exception.
Below is the code...
=========
class A
private void getDialogData(){
IA dmnsnInfo = new IA(strScrnFlag,
strFactType,
strDmnsnTypeId,
hshDmnsnIdName,
"",this);
// I need the data of the IB to be accessed here.
======
Constructor of 'B' which extends JDialog . I've tried using both the constructors of JDialog
public IB(Frame owner, String title, boolean modal) //this gives class caste exception
//public BaseDialog()
super(owner, "title", true);
// super.setModal(modal);
Please let me know where I am going wrong..
Thanks,
Sachin Parandker

Answer 1

In general the way to retrieve data from dialogs is to put the data into fields within the dialog. Then you retrieve them after the dialog is disposed. Note though that the use of JDialog is not recommended in a MDI (Internal Frames) context. Though it basically works JDialogs are too modal, they lock out other window activity.
So you do something like (using JDialog).
class MyDialog extends JDialog {
  String resultsString = null;
  public MyDialog(Frame dlgFrame) {
    super(dlgFrame, "A Title", true);
    JButton ok = new JButton("OK");
    ok.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent e) {
       resultsString = editField.getText();
       dispose();
public void doDialog(Frame parent) {
  MyDialog new MyDialog(parent);
  dlg.show();
  // doesn't get here until dialog is closed
  if(dlg.resultString != null) {
     theValue = dlg.resultString;
     } else {
.. dialog was cancelled
}You can use a JInternalFrame as a "thread modal" dialogue which suspends just the thread that calls it, rather than the whole GUI. After the invoking code invokes show() it should wait() on some convenient object.
Then overide the dispose method of the JInternalFrame so that (having called super.dispose(), it notifies the object in question and ends the wait. However it's crucial that you don't do this from the AWT event dispatching thread (which is likely to happen if it's run directly from an event).