Learning Java, 4th Edition

The Spinner

JList and JComboBox are two ways to let the user choose from a set of values. A JComboBox has added flexibility when it is made editable, but, in general, both of these components are limited in that they can only prompt the user from a fixed set of choices. In Java 1.4, Swing added a component called JSpinner that is useful for large or open-ended sequences of values such as numbers or dates. The JSpinner is a cousin of the JComboBox; it displays a value in a field, but instead of providing a drop-down list of choices, it gives the user a small pair of up and down arrows for moving over a range of values (see Figure 17-5). Like the combo box, a JSpinner can also be made editable, allowing the user to type a valid value directly into the field.

Figure 17-5. Image of DateSelector application

Swing provides three basic types of Spinners, represented by three different data models for the JSpinner component: SpinnerListModel, SpinnerNumberModel, and SpinnerDateModel.

The SpinnerListModel acts like a combo box, specifying a fixed set of objects:

    String [] options = new String [] { "small", "medium", "large", "huge" };
    SpinnerListModel model = new SpinnerListModel( options );
    JSpinner spinner = new JSpinner( model );

You can retrieve the current value from the model at any time:

    String value = (String)model.getValue();

Alternatively, you can register a ChangeListener to receive ...