SWT: A Developer's Notebook

Chapter 8. The SWT Combo

The last of the four basic SWT widget classes is the Combo . Combos are used to gather information by enabling the user to choose from a list of items or to enter text not in the list. It combines the functionality of the List class with functionality from the Text class, hence the name combo. In other toolkits, you may find the combo box referred to by an older name—the drop-down listbox.

Since the Combo is a combination of two classes, you must consider each aspect of the class separately. This chapter begins with an examination of the List aspects of Combo, and then continues with the Text aspects. You will find much of this material familiar after having read the chapters that cover Text and List.

Creating a Combo List

As with all widgets, you must add a Combo to a Shell or other container by creating an instance of the Combo class and passing it the parameters required to create the desired style effects.

How do I do that?

By this stage of the process of learning SWT programming, you should be proficient in the code needed to add a widget to a shell and to specify the style of the widget. For Combo, there are three basic styles—SWT.DROP_DOWN, SWT.READ_ONLY, and SWT.SIMPLE. This code, which creates, sizes, and positions a Combo, should be familiar:

final Combo c = new Combo(s, SWT.READ_ONLY);
c.setBounds(50, 50, 150, 65);

The preceding code creates a Combo that has the SWT.READ_ONLY style. The SWT.READ_ONLY style is used to enable the user to select only ...