Opening True Dialogs

ChildShellExample demonstrated how to open a child window within the confines of a parent window, but this is not the same as opening a true dialog. A dialog window is one that halts processing of code in the parent window until the user takes some action in the dialog. In ChildShellExample, the parent window code continued to execute even while the child window was opened. You can see the effect if you execute Example 2-8.

Example 2-8. Demonstrating the effect of opening a child on the parent

import org.eclipse.swt.widgets.*;

public class ChildShellExample {
    Display d = new Display( );
        
    ChildShellExample( )    {    
        Shell s = new Shell(d);
        s.setSize(500,500);
        s.open( );
        ChildShell cs1 = new ChildShell(s);
        System.out.println("Execution Continues");
        while(!s.isDisposed( )){
            if(!d.readAndDispatch( ))
                d.sleep( );
        }
        d.dispose( );

    }
}

If you execute this version of ChildShellExample, you see that the message is printed to the Console immediately after the child window is opened. What if you need to wait for the user to take some action in the child window before knowing how to proceed? For this, you must use a special form of window known as a dialog. The SWT provides the capability to work with dialogs in the form of the Dialog class.

How do I do that?

The Dialog class enables you to create custom dialogs—those on which you can place any widget you desire. A dialog is simply another type of shell, except that it extends the Dialog class, which encapsulates some additional ...

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