
Similarly, line 23 converts the String “58.32” to a double, and line 24 con-
verts the same String to a Double object.
The usefulness of these wrappers will become clear in the next section of
this chapter, where we discuss dialog boxes.
3.16 Input and Output Using JOptionPane Dialog Boxes
Java provides the JOptionPane class for creating dialog boxes—those famil-
iar pop-up windows that prompt the user to enter a value or notify the user
of an error. The JOptionPane class is in the javax.swing package, so you will
need to provide an import statement in any program that uses a dialog box.
3.16 Input and Output Using JOptionPane Dialog Boxes 151
TABLE 3.16 ...