Listening to Text Components Events with an InputVerifier : JTextComponent « Swing « Java Tutorial

1. Java Tutorial
2. Swing
3. JTextComponent

Do field-level validation of a JTextField. Before focus moves out of a text component, the verifier runs. If not valid, the verifier rejects the change and keeps input focus within the given component.

import java.awt.BorderLayout;

import javax.swing.InputVerifier;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JTextField;
import javax.swing.text.JTextComponent;

public class AddingActionCommandActionListenerSample {
  public static void main(String args[]) {
    final JFrame frame = new JFrame("Default Example");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    JTextField textField = new JTextField();
    frame.add(textField, BorderLayout.NORTH);
    frame.add(new JTextField(), BorderLayout.SOUTH);

    InputVerifier verifier = new InputVerifier() {
      public boolean verify(JComponent input) {
        final JTextComponent source = (JTextComponent)input;
        String text = source.getText();
        if ((text.length() != 0) && !(text.equals("Exit"))) {
              JOptionPane.showMessageDialog (frame, "Can't leave.",
                "Error Dialog", JOptionPane.ERROR_MESSAGE);
          return false;
        } else {
          return true;
        }
      }
    };
    textField.setInputVerifier(verifier);
    
    frame.setSize(250, 150);
    frame.setVisible(true);
  }
}

14.14.JTextComponent
	14.14.1.	JTextComponent: the parent class for all the components used as textual views.
	14.14.2.	Drawing in the Background of a Component
	14.14.3.	Loading and Saving Content
	14.14.4.	Accessing the System Clipboard
	14.14.5.	Default Editor Kit: cutAction
	14.14.6.	Register Keyboard action: registerKeyboardAction
	14.14.7.	CaretListener Interface and CaretEvent Class
	14.14.8.	Restricting Caret Movement: NavigationFilter
	14.14.9.	Remove Key action from Text component
	14.14.10.	Listening to Text Components Events with an ActionListener
	14.14.11.	Listening to JTextField Events with an KeyListener
	14.14.12.	Share Document
	14.14.13.	Listening to Text Components Events with an InputVerifier
	14.14.14.	TextAction Name Constants
	14.14.15.	Using Text Component Actions
	14.14.16.	Listening to Text Components Events with a DocumentListener
	14.14.17.	Text Component Printing
	14.14.18.	GIF Writer
	14.14.19.	Text component supports both cut, copy and paste (using the DefaultEditorKit's built-in actions) and drag and drop
	14.14.20.	Overriding the Default Action of a JTextComponent
	14.14.21.	Modifying Text in a JTextComponent: Insert some text at the beginning
	14.14.22.	Modifying Text in a JTextComponent: Insert some text after the 5th character
	14.14.23.	Modifying Text in a JTextComponent: Append some text
	14.14.24.	Modifying Text in a JTextComponent: Delete the first 5 characters
	14.14.25.	Modifying Text in a JTextComponent: Replace the first 3 characters with some text
	14.14.26.	Limiting the Capacity of a JTextComponent
	14.14.27.	Filter all editing operations on a text component
	14.14.28.	Enabling Text-Dragging on a JTextComponent
	14.14.29.	Enumerating All the Views in a JTextComponent
	14.14.30.	Sharing a Document Between JTextComponents
	14.14.31.	Highlight a word in JTextComponent
	14.14.32.	Remove Highlighting in a JTextComponent
	14.14.33.	Listening for Caret Movement Events in a JTextComponent
	14.14.34.	Listening for Editing Changes in a JTextComponent
	14.14.35.	Moving the Caret of a JTextComponent
	14.14.36.	Setting the Blink Rate of a JTextComponent's Caret
	14.14.37.	Using the Selection of a JTextComponent
	14.14.38.	Better way to set the selection
	14.14.39.	Set the color behind the selected text
	14.14.40.	Set the caret color
	14.14.41.	Document and DocumentFilter