Manipulating Data Using Methods - Java Programming: Comprehensive Concepts and Techniques - page 171

Table 3-12 JOptionPane show Methods

METHOD PURPOSE EXAMPLE

1. showInputDialog() Prompts for input JOptionPane.showInputDialog(null, “message”);

2. showMessageDialog() Displays information to the JOptionPane.showMessageDialog(null, “message”,

user “title bar caption”, messageType);

3. showConfirmDialog() Asks a confirming question, JOptionPane.showConfirmDialog(null, “message”,

like yes/no/cancel “title bar caption”, messageType);

In the first example shown in Table 3-11, the showInputDialog() method
displays a dialog box with a message and a text box for user input. The
showInputDialog() method actually is assigned to a String variable with an
assignment statement. Figure 3-30 shows a typical input dialog box that displays
when the JOptionPane.showInputDialog() method is used.

text box

title bar

message

icon

FIGURE 3-30

The second and third examples in Table 3-12 each use four method argu-
ments. The first argument indicates the placement of the dialog box on the
screen. The Java keyword, null, instructs the program to display the dialog box
centered within the program's active window. The second argument represents
the display area inside the dialog box and can be an object, icon, component, or
String. The third argument indicates the caption that appears on the title bar. The
fourth argument refers to one of various constants defined in the JOptionPane
class. A constant is a value that Java understands to have a certain, intrinsic
meaning. In the case of JOptionPane dialog boxes, the argument refers to one of
several styles of dialog boxes with displayed icons, as shown in Table 3-13 on the
next page.