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<TITLE>Finding Word Boundaries in a JTextComponent (Java Developers Almanac Example)
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<META CONTENT="Patrick Chan" NAME="AUTHOR">
<META CONTENT="Code Examples from The Java Developers Almanac 1.4" NAME="DESCRIPTION">
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<h1>The Java Developers Almanac 1.4</h1>
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Order this book from <a href="/cgi-bin/scripts/redirect.pl?l=ex&url=http://www.amazon.com/exec/obidos/ASIN/0201752808/xeo">Amazon</a>.
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<B><A HREF="../javax.swing.text/pkg.html#JTextComponent">JTextComponent</A></B><font color="#666666" class="xsmall-font">
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<h3>e972. Finding Word Boundaries in a JTextComponent</h3>
This example demonstrates an action that selects the word adjacent to
the caret. If the caret is adjacent to two words, the word following
the caret is selected. The implementation uses
<code>BreakIterator.getWordInstance()</code> to find word boundaries.
<pre> public TextAction selectWordAction = new TextAction("Select Word") {
public void actionPerformed(ActionEvent evt) {
JTextComponent c = getTextComponent(evt);
if (c == null) {
return;
}
int pos = c.getCaretPosition();
try {
// Find start of word from caret
int start = Utilities.getWordStart(c, pos);
// Check if start precedes whitespace
if (start < c.getDocument().getLength()
&& Character.isWhitespace(c.getDocument().getText(start, 1).charAt(0))) {
// Check if caret is at end of word
if (pos > 0
&& !Character.isWhitespace(c.getDocument().getText(pos-1, 1).charAt(0))) {
// Start searching before the caret
start = Utilities.getWordStart(c, pos-1);
} else {
// Caret is not adjacent to a word
start = -1;
}
}
if (start != -1) {
// A non-whitespace character follows start.
// Find end of word from start.
int end = Utilities.getWordEnd(c, start);
// Set selection
c.setSelectionStart(start);
c.setSelectionEnd(end);
}
} catch (BadLocationException e) {
}
}
};
public TextAction selectNextWordAction = new TextAction("Select Next Word") {
public void actionPerformed(ActionEvent evt) {
JTextComponent c = getTextComponent(evt);
if (c == null) {
return;
}
int pos = c.getSelectionStart();
int len = c.getDocument().getLength();
try {
// Find start of next word from selection.
// getNextWord() throws BadLocationException if no word follows pos.
int start = Utilities.getNextWord(c, pos);
// Find end of word from start
int end = Utilities.getWordEnd(c, start);
// Set selection
c.setSelectionStart(start);
c.setSelectionEnd(end);
} catch (BadLocationException e) {
}
}
};
public TextAction selectPrevWordAction = new TextAction("Select Previous Word") {
public void actionPerformed(ActionEvent evt) {
JTextComponent c = getTextComponent(evt);
if (c == null) {
return;
}
int pos = c.getSelectionStart();
int len = c.getDocument().getLength();
try {
// Find start of previous word from selection.
// getPreviousWord() throws BadLocationException if no word precedes pos.
int start = Utilities.getPreviousWord(c, pos);
// Find end of word from start
int end = Utilities.getWordEnd(c, start);
// Set selection
c.setSelectionStart(start);
c.setSelectionEnd(end);
} catch (BadLocationException e) {
}
}
};
</pre>
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<b>Related Examples</b></font></td>
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</table>
e968. <a class="eglink" href="GetText.html?l=rel">
Retrieving Text from a JTextComponent
</a>
<br>
e969. <a class="eglink" href="PartialSeg.html?l=rel">
Retrieving All the Text from a JTextComponent Efficiently
</a>
<br>
e970. <a class="eglink" href="EditTextField.html?l=rel">
Modifying Text in a JTextComponent
</a>
<br>
e971. <a class="eglink" href="ConcurReadText.html?l=rel">
Asynchronously Reading the Contents of a Visible JTextComponent
</a>
<br>
e973. <a class="eglink" href="GetWrappedLines.html?l=rel">
Retrieving the Visible Lines in a JTextComponent
</a>
<br>
e974. <a class="eglink" href="Pos.html?l=rel">
Using a Position in a JTextComponent
</a>
<br>
e975. <a class="eglink" href="LimitText.html?l=rel">
Limiting the Capacity of a JTextComponent
</a>
<br>
e976. <a class="eglink" href="DragEnabledTextArea.html?l=rel">
Enabling Text-Dragging on a JTextComponent
</a>
<br>
e977. <a class="eglink" href="ShareDoc.html?l=rel">
Sharing a Document Between JTextComponents
</a>
<br>
e978. <a class="eglink" href="WalkViews.html?l=rel">
Enumerating All the Views in a JTextComponent
</a>
<br>
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See also:
<a class="eglink" href="/egs/javax.swing.text/pkg.html?l=rel#Actions%20and%20Key%20Bindings">
Actions and Key Bindings
</a>
<a class="eglink" href="/egs/javax.swing.text/pkg.html?l=rel#Caret%20and%20Selection">
Caret and Selection
</a>
<a class="eglink" href="/egs/javax.swing.text/pkg.html?l=rel#Events">
Events
</a>
<a class="eglink" href="/egs/javax.swing.text/pkg.html?l=rel#JEditorPane">
JEditorPane
</a>
<a class="eglink" href="/egs/javax.swing.text/pkg.html?l=rel#JFormattedTextField">
JFormattedTextField
</a>
<a class="eglink" href="/egs/javax.swing.text/pkg.html?l=rel#JTextArea">
JTextArea
</a>
<a class="eglink" href="/egs/javax.swing.text/pkg.html?l=rel#JTextField">
JTextField
</a>
<a class="eglink" href="/egs/javax.swing.text/pkg.html?l=rel#JTextPane">
JTextPane
</a>
<a class="eglink" href="/egs/javax.swing.text/pkg.html?l=rel#Styles">
Styles
</a>
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