Based on JTextField content, enable or disable a JButton
import java.awt.*;
import com.sun.java.swing.*;
import com.sun.java.swing.text.*;
import com.sun.java.swing.event.*;
//import javax.swing... * if Java 2;public class tswing extends JApplet implements DocumentListener{
JButton button;
JTextField textfield;
Document document;
public void init() {
getContentPane().setLayout(new FlowLayout());
textfield = new JTextField(10);
getContentPane().add(textfield);
document = textfield.getDocument();
document.addDocumentListener(this);
button = new JButton("foo");
getContentPane().add(button);
button.setEnabled(false);
} public void changedUpdate(DocumentEvent e ) {
if (e.getDocument()==document)
disableIfEmpty(document);
}
public void insertUpdate( DocumentEvent e ){
if (e.getDocument()==document)
disableIfEmpty(document);
} public void removeUpdate( DocumentEvent e ){
if (e.getDocument()==document)
disableIfEmpty(document);
} public void disableIfEmpty(Document d) {
button.setEnabled(d.getLength() > 0);
}
}
import java.awt.*;
import com.sun.java.swing.*;
import com.sun.java.swing.text.*;
import com.sun.java.swing.event.*;
//import javax.swing... * if Java 2;public class tswing extends JApplet implements DocumentListener{
JButton button;
JTextField textfield;
Document document;
public void init() {
getContentPane().setLayout(new FlowLayout());
textfield = new JTextField(10);
getContentPane().add(textfield);
document = textfield.getDocument();
document.addDocumentListener(this);
button = new JButton("foo");
getContentPane().add(button);
button.setEnabled(false);
} public void changedUpdate(DocumentEvent e ) {
if (e.getDocument()==document)
disableIfEmpty(document);
}
public void insertUpdate( DocumentEvent e ){
if (e.getDocument()==document)
disableIfEmpty(document);
} public void removeUpdate( DocumentEvent e ){
if (e.getDocument()==document)
disableIfEmpty(document);
} public void disableIfEmpty(Document d) {
button.setEnabled(d.getLength() > 0);
}
}
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