JDialog : Java Glossary

For simple questions, you can use JOptionPane.showInputDialog which comes in two versions, one that just prompts for a String and one that selects an item from a list.

Dialog is the AWT (Advanced Windowing Toolkit) equivalent of JDialog.

Gotchas

• If JDialogs fail to paint anything, it could be because you forgot to do a setSize, validate(), or setVisible( true ).
• JDialog.setBackground does not work. Use jdialog.getContentPane().setBackground( aColour ) and jdialog.getContentPane().add( child );
• JDialog constructors want a Frame/JFrame as parent. Unfortunately, JApplet is an Applet, which is a Panel, not a Frame. This can be a problem. There are a number of ways to handle it:
  1. In Java version 1.4 or later you can pass null as the parent Frame. However, this is buggy when the encloding frame in an Applet/JApplet.
  2. Create a dummy non-displaying JFrame for the JDialog live in. Keep in mind you will not recover all the memory unless you explicity dispose the Frame.
  3. Pop up a visible empty JFrame for the JDialog live in.
  4. To embed a JDialog in an Applet, you must chase the Component.getParent chain until you find an instanceof Frame. Use the following getParentFrame method to get a handle on the enclosing Frame.

     The above code is part of the com.mindprod.common11.Misc class. You can download it as part of the common11 bundle.

Sample Code

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