Swing Hacks

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Chapter 7, Text

#48 Make Text Components Searchable

HACK

The continueSearch( ) method just calls find( ) on the matcher, if it exists. If

find( ) returns true, meaning it found a match somewhere, it sets the selec-

tion. Selections are defined by a caret with a dot. The dot represents the

selection point. By setting the dot at the start of the match and then moving

it with the

moveDot( )

function, it will create a selection between the start

and ending points. Finally,

setSelectionVisible(true)

scrolls the target

component, if needed, to make the selection visible on screen.

The action listener implementation will call

continueSearch( ) whenever an

action is performed. Both

JButton

s and

JTextField

s produce actions—the

former when they are clicked, and the latter when the user hits the Return

key. Listening for action events is an easy way of providing a hook to repeat

the search:

/* ActionListener implementation */

public void actionPerformed(ActionEvent evt) {

continueSearch( );

}

Since the matcher object remembers its place, each time find is called it will

continue searching from the current location. This means the user can just

hit Enter over and over to loop through the results in the document, high-

lighting each one as it goes along.

Adding Search to Swing Components

The following code creates a typical search interface. There is a large

JTextArea below a text field. The IncrementalSearch is attached to the text

area through its constructor. The search field is connected via the document

and action listeners. Once the class is put all together, it will look like

Figure 7-1.

Figure 7-1. Incremental repeatable search of a JTextArea