Java AWT Reference

8

Input Fields

In this chapter:

• Text Component
• TextField
• TextArea
• Extending TextField

There are two fundamental ways for users to provide input to a program: they can type on a keyboard, or they can select something (a button, a menu item, etc.) using a mouse. When you want a user to provide input to your program, you can display a list of choices to choose from or allow the user to interact with your program by typing with the keyboard. Presenting choices to the user is covered in Chapter 9, Pick Me. As far as keyboard input goes, the java.awt package provides two options. The TextField class is a single line input field, while the TextArea class is a multiline one. Both TextField and TextArea are subclasses of the class TextComponent, which contains all the common functionality of the two. TextComponent is a subclass of Component, which is a subclass of Object. So you inherit all of these methods when you work with either TextField or TextArea.

8.1 Text Component

By themselves, the TextField and TextArea classes are fairly robust. However, in order to reduce duplication between the classes, they both inherit a number of methods from the TextComponent class. The constructor for TextComponent is package private, so you cannot create an instance of it yourself. Some of the activities shared by TextField and TextArea through the TextComponent methods include setting the text, getting the text, selecting the text, and making it read-only.

8.1.1 TextComponent Methods

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