Android How to Program, 3/e

I.7 JComboBox; Using an Anonymous Inner Class for Event Handling

A combo box (sometimes called a drop-down list) enables the user to select one item from a list (Fig. I.9). Combo boxes are implemented with class JComboBox, which extends class JComponent. JComboBoxes generate ItemEvents just as JCheckBoxes and JRadioButtons do. This example also demonstrates a special form of inner class that’s used frequently in event handling. The app (Figs. I.8–I.9) uses a JComboBox to provide a list of four image-file names from which the user can select one image to display. When the user selects a name, the app displays the corresponding image as an Icon on a JLabel. Class ComboBox-Test (Fig. I.9) contains the main method that executes this app. The screen ...