Java The Complete Reference, Seventh Edition

Using a TextField

TheTextFieldclass implements a single-line text-entry area, usually called anedit control.

Text fields allow the user to enter strings and to edit the text using the arrow keys, cut and

paste keys, and mouse selections.TextFieldis a subclass ofTextComponent.TextField

defines the following constructors:

TextField( ) throws HeadlessException

TextField(intnumChars) throws HeadlessException

TextField(Stringstr) throws HeadlessException

TextField(Stringstr, intnumChars) throws HeadlessException

The first version creates a default text field. The second form creates a text field that is

numCharscharacters wide. The third form initializes the text field with the string contained

instr.The fourth form initializes a text field and sets its width.

TextField(and its superclassTextComponent) provides several methods that allow you

to utilize a text field. To obtain the string currently contained in the text field, callgetText( ).

To set the text, callsetText( ). These methods are as follows:

String getText( )

void setText(Stringstr)

Here,stris the new string.

The user can select a portion of the text in a text field. Also, you can select a portion of

text under program control by usingselect( ). Your program can obtain the currently selected

text by callinggetSelectedText( ). These methods are shown here:

String getSelectedText( )

void select(intstartIndex, intendIndex)

getSelectedText( )returns the selected text. Theselect( )method selects the characters

beginning atstartIndexand ending atendIndex–1.

Chapter 24: Using AWT Controls, Layout Managers, and Menus 719

FIGURE 24-6 Sample output from theSBDemoapplet