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/*
Core SWING Advanced Programming
By Kim Topley
ISBN: 0 13 083292 8
Publisher: Prentice Hall
*/
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.text.BadLocationException;
import javax.swing.text.Document;
public class LookAheadExample {
public static void main(String[] args) {
try {
UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
} catch (Exception evt) {}
JFrame f = new JFrame("Text Lookahead");
StringArrayLookAhead lookAhead = new StringArrayLookAhead(values);
LookAheadTextField tf = new LookAheadTextField(20, lookAhead);
f.getContentPane().add(tf, "Center");
f.pack();
f.setVisible(true);
}
// The possible look-ahead values
public static String[] values = new String[] { "aback", "abacus",
"abandon", "abashed", "abate", "abdomen", "abide", "ability",
"baby", "back", "backache", "backgammon" };
}
class LookAheadTextField extends JTextField {
public LookAheadTextField() {
this(0, null);
}
public LookAheadTextField(int columns) {
this(columns, null);
}
public LookAheadTextField(int columns, TextLookAhead lookAhead) {
super(columns);
setLookAhead(lookAhead);
addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
// Remove any existing selection
setCaretPosition(getDocument().getLength());
}
});
addFocusListener(new FocusListener() {
public void focusGained(FocusEvent evt) {
}
public void focusLost(FocusEvent evt) {
if (evt.isTemporary() == false) {
// Remove any existing selection
setCaretPosition(getDocument().getLength());
}
}
});
}
public void setLookAhead(TextLookAhead lookAhead) {
this.lookAhead = lookAhead;
}
public TextLookAhead getLookAhead() {
return lookAhead;
}
public void replaceSelection(String content) {
super.replaceSelection(content);
if (isEditable() == false || isEnabled() == false) {
return;
}
Document doc = getDocument();
if (doc != null && lookAhead != null) {
try {
String oldContent = doc.getText(0, doc.getLength());
String newContent = lookAhead.doLookAhead(oldContent);
if (newContent != null) {
// Substitute the new content
setText(newContent);
// Highlight the added text
setCaretPosition(newContent.length());
moveCaretPosition(oldContent.length());
}
} catch (BadLocationException e) {
// Won't happen
}
}
}
protected TextLookAhead lookAhead;
// The TextLookAhead interface
public interface TextLookAhead {
public String doLookAhead(String key);
}
}
class StringArrayLookAhead implements LookAheadTextField.TextLookAhead {
public StringArrayLookAhead() {
values = new String[0];
}
public StringArrayLookAhead(String[] values) {
this.values = values;
}
public void setValues(String[] values) {
this.values = values;
}
public String[] getValues() {
return values;
}
public String doLookAhead(String key) {
int length = values.length;
// Look for a string that starts with the key
for (int i = 0; i < length; i++) {
if (values[i].startsWith(key) == true) {
return values[i];
}
}
// No match found - return null
return null;
}
protected String[] values;
}
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