Based on JTextField content, enable or disable a JButton

     

import javax.swing.JButton;
import javax.swing.JTextField;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.text.Document;

public class Main {
  JButton button = new JButton("foo");
  JTextField textfield = new JTextField(10);
  Document document;

  public Main() {
    document = textfield.getDocument();
    document.addDocumentListener(new JButtonStateController());
  }
  class JButtonStateController implements DocumentListener {
    JButtonStateController() {
    }

    public void changedUpdate(DocumentEvent e) {
      disableIfEmpty(e);
    }

    public void insertUpdate(DocumentEvent e) {
      disableIfEmpty(e);
    }

    public void removeUpdate(DocumentEvent e) {
      disableIfEmpty(e);
    }

    public void disableIfEmpty(DocumentEvent e) {
      button.setEnabled(e.getDocument().getLength() > 0);
    }
  }
}

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Based on JTextField content, enable or disable a JButton : TextField « Swing JFC « Java

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