Page 131 - Introduction to Programming with Java: A Problem Solving Approach

3.24 GUI Track: Input and Output with JOptionPane (Optional) 97 center of the screen. To go with the default position, specify null for the first argument. The second argu-
ment specifies the message that appears in the dialog box.
Input Dialog Box
Note that a dialog box is often referred to simply as a dialog. Both terms are acceptable. There are several types of JOptionPane dialogs. We consider two of them—the message dialog for output and the input di- alog for input. We’ve already described the message dialog. That’s what showMessageDialog produces. We’ll now look at the input dialog.
The input dialog displays a prompt message and an input box. The top four dialogs in Figure 3.18 are input dialogs. These display a question mark icon as a visual cue that the dialog is asking a question and waiting for user input. Clicking OK processses the value entered. Clicking Cancel closes the dialog box without processing.
1. Initial display
prompt message
input box
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2. After entering “painting, dogs playing poker”
3. After clicking OK and entering 42.22
4. After clicking OK and entering 2 5. After clicking OK
Figure 3.18 Sample session for PrintPOGUI program