Java Tutorial/Swing/JTextField

Adding ActionListener to JTextField

import java.awt.event.ActionEvent;
import javax.swing.JFrame;
import javax.swing.JTextField;
public class AddingActionListenerJTextField {
  public static void main(String[] a) {
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JTextField jTextField1 = new JTextField();
    jTextField1.setText("jTextField1");
    jTextField1.addActionListener(new java.awt.event.ActionListener() {
      public void actionPerformed(ActionEvent e) {
        System.out.println("action");
      }
    });
    frame.add(jTextField1);
    frame.setSize(300, 200);
    frame.setVisible(true);
  }
}

Add key listener event handler to JTextField

import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.HeadlessException;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
public class Main extends JFrame {
  public Main() throws HeadlessException {
    setSize(200, 200);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setLayout(new FlowLayout(FlowLayout.LEFT));
    JLabel usernameLabel = new JLabel("Username: ");
    JTextField usernameTextField = new JTextField();
    usernameTextField.setPreferredSize(new Dimension(100, 20));
    add(usernameLabel);
    add(usernameTextField);
    usernameTextField.addKeyListener(new KeyAdapter() {
      public void keyReleased(KeyEvent e) {
        JTextField textField = (JTextField) e.getSource();
        String text = textField.getText();
        textField.setText(text.toUpperCase());
      }
      public void keyTyped(KeyEvent e) {
      }
      public void keyPressed(KeyEvent e) {
      }
    });
  }
  public static void main(String[] args) {
    new Main().setVisible(true);
  }
}

Aligning the Text in a JTextField Component

import javax.swing.JTextField;
public class Main {
  public static void main(String[] argv) {
    JTextField textfield = new JTextField("Initial Text");
    // Left-justify the text
    textfield.setHorizontalAlignment(JTextField.LEFT);
    // Center the text
    textfield.setHorizontalAlignment(JTextField.CENTER);
    // Right-justify the text
    textfield.setHorizontalAlignment(JTextField.RIGHT);
  }
}

Apply special filter to a JTextField

import java.awt.FlowLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.PlainDocument;
class JTextFieldFilter extends PlainDocument {
  public static final String NUMERIC = "0123456789";
  protected String acceptedChars = null;
  protected boolean negativeAccepted = false;
  public JTextFieldFilter() {
    this(NUMERIC);
  }
  public JTextFieldFilter(String acceptedchars) {
    acceptedChars = acceptedchars;
  }
  public void setNegativeAccepted(boolean negativeaccepted) {
    if (acceptedChars.equals(NUMERIC)) {
      negativeAccepted = negativeaccepted;
      acceptedChars += "-";
    }
  }
  public void insertString(int offset, String str, AttributeSet attr) throws BadLocationException {
    if (str == null)
      return;
    for (int i = 0; i < str.length(); i++) {
      if (acceptedChars.indexOf(str.valueOf(str.charAt(i))) == -1)
        return;
    }
    if (negativeAccepted && str.indexOf("-") != -1) {
      if (str.indexOf("-") != 0 || offset != 0) {
        return;
      }
    }
    super.insertString(offset, str, attr);
  }
}
public class Main extends JFrame{
  public static void main(String[] argv) throws Exception {
    new Main();
  }
  public Main() {
    JTextField tf1, tf1b, tf1c, tf2, tf3;
    JLabel l1, l1b, l1c, l2, l3;
    setLayout(new FlowLayout());
    //
    l1 = new JLabel("only numerics");
    tf1 = new JTextField(10);
    getContentPane().add(l1);
    getContentPane().add(tf1);
    tf1.setDocument(new JTextFieldFilter(JTextFieldFilter.NUMERIC));
    setSize(300,300);
    setVisible(true);
  }
}

Based on JTextField content, enable or disable a JButton

import java.awt.BorderLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.text.Document;
public class Main {
  public Main() {
    JButton button = new JButton("foo");
    JTextField textField = new JTextField(10);
    Document document = textField.getDocument();
    document.addDocumentListener(new JButtonStateController(button));
  
    JFrame frame = new JFrame();
    frame.add(button,BorderLayout.WEST);
    frame.add(textField,BorderLayout.CENTER);
    frame.setSize(300,300);
    frame.setVisible(true);
  }
}
class JButtonStateController implements DocumentListener {
 JButton button;
  
  JButtonStateController(JButton button) {
     this.button = button ;
  }
  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);
  }
}

Customizing a JTextField Look and Feel

Property StringObject TypetextColortextHighlightColortextHighlightTextColortextInactiveTextColorTextField.actionMapActionMapTextField.backgroundColorTextField.borderBorderTextField.caretAspectRatioNumberTextField.caretBlinkRateIntegerTextField.caretForegroundColorTextField.darkShadowColorTextField.disabledBackgroundColorTextField.focusInputMapInputMapTextField.fontFontTextField.foregroundColorTextField.highlightColorTextField.inactiveBackgroundColorTextField.inactiveForegroundColorTextField.keyBindingsKeyBinding[ ]TextField.lightColorTextField.marginInsetsTextField.selectionBackgroundColorTextField.selectionForegroundColorTextField.shadowColorTextFieldUIString

Cut, paste, and copy in a JTextField

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.event.CaretEvent;
import javax.swing.event.CaretListener;
public class Main {
  public static void main(String args[]) {
    final JTextField textField = new JTextField(15);
    JButton buttonCut = new JButton("Cut");
    JButton buttonPaste = new JButton("Paste");
    JButton buttonCopy = new JButton("Copy");
    JFrame jfrm = new JFrame("Cut, Copy, and Paste");
    jfrm.setLayout(new FlowLayout());
    jfrm.setSize(230, 150);
    jfrm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    buttonCut.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent le) {
        textField.cut();
      }
    });
    buttonPaste.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent le) {
        textField.paste();
      }
    });
    buttonCopy.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent le) {
        textField.copy();
      }
    });
    textField.addCaretListener(new CaretListener() {
      public void caretUpdate(CaretEvent ce) {
        System.out.println("All text: " + textField.getText());
        if (textField.getSelectedText() != null)
          System.out.println("Selected text: " + textField.getSelectedText());
        else
          System.out.println("Selected text: ");
      }
    });
    jfrm.add(textField);
    jfrm.add(buttonCut);
    jfrm.add(buttonPaste);
    jfrm.add(buttonCopy);
    jfrm.setVisible(true);
  }
}

Drag and drop Text Demo

import java.awt.Container;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JTextField;
public class DragDropText extends JFrame {
  public static void main(String[] args) {
    new DragDropText().setVisible(true);
  }
  public DragDropText() {
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JTextField field1 = new JTextField("Life"s a drag", 20);
    JTextField field2 = new JTextField("and then you drop", 20);
    field1.setDragEnabled(true);
    field2.setDragEnabled(true);
    Container content = getContentPane();
    content.setLayout(new BoxLayout(content, BoxLayout.Y_AXIS));
    content.add(field1);
    content.add(field2);
    pack();
  }
}

extends JTextField to create integer JTextField

/*
 * Copyright (C) 2001-2003 Colin Bell
 * colbell@users.sourceforge.net
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
import java.awt.Toolkit;
import javax.swing.JTextField;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.Document;
import javax.swing.text.PlainDocument;
/**
 * This class is a <CODE>TextField</CODE> that only allows integer
 * values to be entered into it.
 *
 * @author 
 */
public class IntegerField extends JTextField
{
  /**
   * Default ctor.
   */
  public IntegerField()
  {
    super();
  }
  /**
   * Ctor specifying the field width.
   *
   * @param cols  Number of columns.
   */
  public IntegerField(int cols)
  {
    super(cols);
  }
  /**
   * Retrieve the contents of this field as an <TT>int</TT>.
   *
   * @return  the contents of this field as an <TT>int</TT>.
   */
  public int getInt()
  {
    final String text = getText();
    if (text == null || text.length() == 0)
    {
      return 0;
    }
    return Integer.parseInt(text);
  }
  /**
   * Set the contents of this field to the passed <TT>int</TT>.
   *
   * @param value The new value for this field.
   */
  public void setInt(int value)
  {
    setText(String.valueOf(value));
  }
  /**
   * Create a new document model for this control that only accepts
   * integral values.
   *
   * @return  The new document model.
   */
  protected Document createDefaultModel()
  {
    return new IntegerDocument();
  }
  /**
   * This document only allows integral values to be added to it.
   */
  static class IntegerDocument extends PlainDocument
  {
    public void insertString(int offs, String str, AttributeSet a)
      throws BadLocationException
    {
      if (str != null)
      {
        try
        {
          Integer.decode(str);
          super.insertString(offs, str, a);
        }
        catch (NumberFormatException ex)
        {
          Toolkit.getDefaultToolkit().beep();
        }
      }
    }
  }
}

Format JTextField"s text to uppercase

import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.HeadlessException;
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.text.AbstractDocument;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.DocumentFilter;
public class Main extends JFrame {
  public Main() throws HeadlessException {
    setSize(200, 200);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setLayout(new FlowLayout(FlowLayout.LEFT));
    DocumentFilter filter = new UppercaseDocumentFilter();
    JTextField firstName = new JTextField();
    firstName.setPreferredSize(new Dimension(100, 20));
    ((AbstractDocument) firstName.getDocument()).setDocumentFilter(filter);
    JTextField lastName = new JTextField();
    lastName.setPreferredSize(new Dimension(100, 20));
    ((AbstractDocument) lastName.getDocument()).setDocumentFilter(filter);
    add(firstName);
    add(lastName);
  }
  public static void main(String[] args) {
    new Main().setVisible(true);
  }
}
class UppercaseDocumentFilter extends DocumentFilter {
  public void insertString(DocumentFilter.FilterBypass fb, int offset, String text,
      AttributeSet attr) throws BadLocationException {
    fb.insertString(offset, text.toUpperCase(), attr);
  }
  public void replace(DocumentFilter.FilterBypass fb, int offset, int length, String text,
      AttributeSet attrs) throws BadLocationException {
    fb.replace(offset, length, text.toUpperCase(), attrs);
  }
}

HighLight painter and JTextField

/*
 * Copyright (c) 1995 - 2008 Sun Microsystems, Inc.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Sun Microsystems nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
/*
 * TextFieldDemo.java requires one additional file:
 * content.txt
 */
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.GroupLayout;
import javax.swing.InputMap;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.KeyStroke;
import javax.swing.LayoutStyle;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.WindowConstants;
import javax.swing.GroupLayout.ParallelGroup;
import javax.swing.GroupLayout.SequentialGroup;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.text.BadLocationException;
import javax.swing.text.DefaultHighlighter;
import javax.swing.text.Highlighter;
public class TextFieldDemo extends JFrame implements DocumentListener {
  private JTextField entry;
  private JLabel jLabel1;
  private JScrollPane jScrollPane1;
  private JLabel status;
  private JTextArea textArea;
  final static Color HILIT_COLOR = Color.LIGHT_GRAY;
  final static Color ERROR_COLOR = Color.PINK;
  final static String CANCEL_ACTION = "cancel-search";
  final Color entryBg;
  final Highlighter hilit;
  final Highlighter.HighlightPainter painter;
  public TextFieldDemo() {
    initComponents();
    InputStream in = getClass().getResourceAsStream("content.txt");
    try {
      textArea.read(new InputStreamReader(in), null);
    } catch (IOException e) {
      e.printStackTrace();
    }
    hilit = new DefaultHighlighter();
    painter = new DefaultHighlighter.DefaultHighlightPainter(HILIT_COLOR);
    textArea.setHighlighter(hilit);
    entryBg = entry.getBackground();
    entry.getDocument().addDocumentListener(this);
    InputMap im = entry.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
    ActionMap am = entry.getActionMap();
    im.put(KeyStroke.getKeyStroke("ESCAPE"), CANCEL_ACTION);
    am.put(CANCEL_ACTION, new CancelAction());
  }
  /**
   * This method is called from within the constructor to initialize the form.
   */
  private void initComponents() {
    entry = new JTextField();
    textArea = new JTextArea();
    status = new JLabel();
    jLabel1 = new JLabel();
    setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    setTitle("TextFieldDemo");
    textArea.setColumns(20);
    textArea.setLineWrap(true);
    textArea.setRows(5);
    textArea.setWrapStyleWord(true);
    textArea.setEditable(false);
    jScrollPane1 = new JScrollPane(textArea);
    jLabel1.setText("Enter text to search:");
    GroupLayout layout = new GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    // Create a parallel group for the horizontal axis
    ParallelGroup hGroup = layout
        .createParallelGroup(GroupLayout.Alignment.LEADING);
    // Create a sequential and a parallel groups
    SequentialGroup h1 = layout.createSequentialGroup();
    ParallelGroup h2 = layout
        .createParallelGroup(GroupLayout.Alignment.TRAILING);
    // Add a container gap to the sequential group h1
    h1.addContainerGap();
    // Add a scroll pane and a label to the parallel group h2
    h2.addComponent(jScrollPane1, GroupLayout.Alignment.LEADING,
        GroupLayout.DEFAULT_SIZE, 450, Short.MAX_VALUE);
    h2.addComponent(status, GroupLayout.Alignment.LEADING,
        GroupLayout.DEFAULT_SIZE, 450, Short.MAX_VALUE);
    // Create a sequential group h3
    SequentialGroup h3 = layout.createSequentialGroup();
    h3.addComponent(jLabel1);
    h3.addPreferredGap(LayoutStyle.ruponentPlacement.RELATED);
    h3.addComponent(entry, GroupLayout.DEFAULT_SIZE, 321, Short.MAX_VALUE);
    // Add the group h3 to the group h2
    h2.addGroup(h3);
    // Add the group h2 to the group h1
    h1.addGroup(h2);
    h1.addContainerGap();
    // Add the group h1 to the hGroup
    hGroup.addGroup(GroupLayout.Alignment.TRAILING, h1);
    // Create the horizontal group
    layout.setHorizontalGroup(hGroup);
    // Create a parallel group for the vertical axis
    ParallelGroup vGroup = layout
        .createParallelGroup(GroupLayout.Alignment.LEADING);
    // Create a sequential group v1
    SequentialGroup v1 = layout.createSequentialGroup();
    // Add a container gap to the sequential group v1
    v1.addContainerGap();
    // Create a parallel group v2
    ParallelGroup v2 = layout
        .createParallelGroup(GroupLayout.Alignment.BASELINE);
    v2.addComponent(jLabel1);
    v2.addComponent(entry, GroupLayout.PREFERRED_SIZE,
        GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE);
    // Add the group v2 tp the group v1
    v1.addGroup(v2);
    v1.addPreferredGap(javax.swing.LayoutStyle.ruponentPlacement.RELATED);
    v1.addComponent(jScrollPane1, GroupLayout.DEFAULT_SIZE, 233,
        Short.MAX_VALUE);
    v1.addPreferredGap(javax.swing.LayoutStyle.ruponentPlacement.RELATED);
    v1.addComponent(status);
    v1.addContainerGap();
    // Add the group v1 to the group vGroup
    vGroup.addGroup(v1);
    // Create the vertical group
    layout.setVerticalGroup(vGroup);
    pack();
  }
  public void search() {
    hilit.removeAllHighlights();
    String s = entry.getText();
    if (s.length() <= 0) {
      message("Nothing to search");
      return;
    }
    String content = textArea.getText();
    int index = content.indexOf(s, 0);
    if (index >= 0) { // match found
      try {
        int end = index + s.length();
        hilit.addHighlight(index, end, painter);
        textArea.setCaretPosition(end);
        entry.setBackground(entryBg);
        message(""" + s + "" found. Press ESC to end search");
      } catch (BadLocationException e) {
        e.printStackTrace();
      }
    } else {
      entry.setBackground(ERROR_COLOR);
      message(""" + s + "" not found. Press ESC to start a new search");
    }
  }
  void message(String msg) {
    status.setText(msg);
  }
  // DocumentListener methods
  public void insertUpdate(DocumentEvent ev) {
    search();
  }
  public void removeUpdate(DocumentEvent ev) {
    search();
  }
  public void changedUpdate(DocumentEvent ev) {
  }
  class CancelAction extends AbstractAction {
    public void actionPerformed(ActionEvent ev) {
      hilit.removeAllHighlights();
      entry.setText("");
      entry.setBackground(entryBg);
    }
  }
  public static void main(String args[]) {
    // Schedule a job for the event dispatch thread:
    // creating and showing this application"s GUI.
    SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        // Turn off metal"s use of bold fonts
        UIManager.put("swing.boldMetal", Boolean.FALSE);
        new TextFieldDemo().setVisible(true);
      }
    });
  }
}

Horizontal Alignment

By default, the text alignment is left-justified.

public void setHorizontalAlignment(int alignment) method takes an argument of

1. JTextField.LEFT,
2. JTextField.CENTER,
3. JTextField.RIGHT,
4. JTextField.LEADING (the default), or
5. JTextField.TRAILING.

import java.awt.BorderLayout;
import java.awt.event.KeyEvent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class LabelSampleHorizontalAlignment {
  public static void main(String args[]) {
    JFrame frame = new JFrame("Label Focus Example");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JPanel panel = new JPanel(new BorderLayout());
    JLabel label = new JLabel("Name: ");
    label.setDisplayedMnemonic(KeyEvent.VK_N);
    JTextField textField = new JTextField();
    textField.setHorizontalAlignment(JTextField.CENTER) ;
    
    label.setLabelFor(textField);
    panel.add(label, BorderLayout.WEST);
    panel.add(textField, BorderLayout.CENTER);
    frame.add(panel, BorderLayout.NORTH);
    frame.setSize(250, 150);
    frame.setVisible(true);
  }
}

JTextField with a JScrollBar for Scrolling

Built inside the JTextField is a scrollable area used when the width of the component"s contents exceeds its visible horizontal space.

A BoundedRangeModel controls this scrolling area.

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BoundedRangeModel;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollBar;
import javax.swing.JTextField;
public class TextSlider {
  public static void main(String args[]) {
    JFrame frame = new JFrame("Text Slider");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    final JTextField textField = new JTextField();
    JScrollBar scrollBar = new JScrollBar(JScrollBar.HORIZONTAL);
    JPanel panel = new JPanel();
    panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS));
    BoundedRangeModel brm = textField.getHorizontalVisibility();
    scrollBar.setModel(brm);
    panel.add(textField);
    panel.add(scrollBar);
    final TextSlider ts = new TextSlider();
    textField.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        System.out.println("Text: " + textField.getText());
      }
    });
    frame.add(panel, BorderLayout.NORTH);
    frame.setSize(300, 100);
    frame.setVisible(true);
  }
}

Limit JTextField input to a maximum length

import java.awt.FlowLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.PlainDocument;
class JTextFieldLimit extends PlainDocument {
  private int limit;
  JTextFieldLimit(int limit) {
    super();
    this.limit = limit;
  }
  JTextFieldLimit(int limit, boolean upper) {
    super();
    this.limit = limit;
  }
  public void insertString(int offset, String str, AttributeSet attr) throws BadLocationException {
    if (str == null)
      return;
    if ((getLength() + str.length()) <= limit) {
      super.insertString(offset, str, attr);
    }
  }
}
public class Main extends JFrame {
  JTextField textfield1;
  JLabel label1;
  public void init() {
    setLayout(new FlowLayout());
    label1 = new JLabel("max 10 chars");
    textfield1 = new JTextField(15);
    add(label1);
    add(textfield1);
    textfield1.setDocument(new JTextFieldLimit(10));
    
    setSize(300,300);
    setVisible(true);
  }
}

Make a Text Field two columns wide

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class Main {
  public static void main(String[] args) {
    JTextField tf = new JTextField("mm");
    tf.setPreferredSize(tf.getPreferredSize());
    tf.setText("");
    JPanel pHacked = new JPanel();
    pHacked.add(tf);
    JPanel pStock = new JPanel();
    pStock.add(new JTextField(2));
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setLayout(new java.awt.GridLayout(0, 1));
    frame.add(pHacked);
    frame.add(pStock);
    frame.setSize(150, 150);
    frame.setVisible(true);
    tf.requestFocus();
  }
}

Right justified JTextfield content

import javax.swing.JTextField;
public class Main{
  public static void main(String[] argv) {
    JTextField textfield = new JTextField(10);
    textfield.setHorizontalAlignment(JTextField.RIGHT);
  }
}

Set the focus on a particular JTextField

import javax.swing.JTextField;
import javax.swing.SwingUtilities;
public class Main {
  public static void main(String[] argv) throws Exception {
    final JTextField textfield = new JTextField(10);
    SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        textfield.requestFocus();
      }
    });
  }
}

Sharing Data Models between two JTextField

The JTextField component is the text component for a single line of input.

import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.text.Document;
public class ShareModel {
  public static void main(String args[]) {
    JFrame frame = new JFrame("Sharing Sample");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JTextArea textarea1 = new JTextArea();
    Document document = textarea1.getDocument();
    JTextArea textarea2 = new JTextArea(document);
    JTextArea textarea3 = new JTextArea(document);
    frame.setLayout(new BoxLayout(frame.getContentPane(), BoxLayout.Y_AXIS));
    frame.add(new JScrollPane(textarea1));
    frame.add(new JScrollPane(textarea2));
    frame.add(new JScrollPane(textarea3));
    frame.setSize(300, 400);
    frame.setVisible(true);
  }
}

Subclass InputVerfier

import javax.swing.InputVerifier;
import javax.swing.JComponent;
import javax.swing.JTextField;
public class Main {
  public static void main(String[] args) {
    JTextField tf = new JTextField("");
    tf.setInputVerifier(new MyInputVerifier());
  }
}
class MyInputVerifier extends InputVerifier {
  public boolean verify(JComponent input) {
    JTextField tf = (JTextField) input;
    String pass = tf.getText();
    return pass.equals("A");
  }
}

To make sure that the end of the contents is visible

By changing the scrollOffset setting, you can control which part of the text field is visible.

To make sure that the end of the contents is visible, you need to ask the horizontalVisibility property what the extent of the BoundedRangeModel is, to determine the width of the range, and then set the scrollOffset setting to the extent setting, as follows:

import java.awt.BorderLayout;
import java.awt.event.KeyEvent;
import javax.swing.BoundedRangeModel;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class LabelSampleBoundedRangeModel {
  public static void main(String args[]) {
    JFrame frame = new JFrame("Label Focus Example");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JPanel panel = new JPanel(new BorderLayout());
    JLabel label = new JLabel("Name: ");
    label.setDisplayedMnemonic(KeyEvent.VK_N);
    JTextField textField = new JTextField();
    label.setLabelFor(textField);
    panel.add(label, BorderLayout.WEST);
    panel.add(textField, BorderLayout.CENTER);
    frame.add(panel, BorderLayout.NORTH);
    frame.setSize(250, 150);
    frame.setVisible(true);
    textField.setText("Loooooooooooooooooooooooooooooooooooooooooooooooooooooooong");
    BoundedRangeModel model = textField.getHorizontalVisibility();
    int extent = model.getExtent();
    textField.setScrollOffset(extent);
    System.out.println("extent:"+extent);

  }
}

Use the write() method to write the contents

import java.awt.BorderLayout;
import java.awt.event.KeyEvent;
import java.io.FileWriter;
import java.io.IOException;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class LabelSampleSaveText {
  public static void main(String args[]) {
    JFrame frame = new JFrame("Label Focus Example");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JPanel panel = new JPanel(new BorderLayout());
    JLabel label = new JLabel("Name: ");
    label.setDisplayedMnemonic(KeyEvent.VK_N);
    JTextField textField = new JTextField();
    label.setLabelFor(textField);
    panel.add(label, BorderLayout.WEST);
    panel.add(textField, BorderLayout.CENTER);
    frame.add(panel, BorderLayout.NORTH);
    frame.add(new JButton("Somewhere Else"), BorderLayout.SOUTH);
    frame.setSize(250, 150);
    frame.setVisible(true);
    textField.setText("your text");
    String filename = "test.txt";
    FileWriter writer = null;
    try {
      writer = new FileWriter(filename);
      textField.write(writer);
    } catch (IOException exception) {
      System.err.println("Save oops");
    } finally {
      if (writer != null) {
        try {
          writer.close();
        } catch (IOException exception) {
          System.err.println("Error closing writer");
          exception.printStackTrace();
        }
      }
    }
  }
}

Using Actions with Text Components: JTextField

import java.util.Arrays;
import java.util.ruparator;
import javax.swing.Action;
import javax.swing.JTextField;
import javax.swing.text.JTextComponent;
public class ListActionsJTextField {
  public static void main(String args[]) {
    JTextComponent component = new JTextField();
    // Process action list
    Action actions[] = component.getActions();
    // Define comparator to sort actions
    Comparator<Action> comparator = new Comparator<Action>() {
      public int compare(Action a1, Action a2) {
        String firstName = (String) a1.getValue(Action.NAME);
        String secondName = (String) a2.getValue(Action.NAME);
        return firstName.rupareTo(secondName);
      }
    };
    Arrays.sort(actions, comparator);
    int count = actions.length;
    System.out.println("Count: " + count);
    for (int i = 0; i < count; i++) {
      System.out.printf("%28s : %s\n",actions[i].getValue(Action.NAME),actions[i].getClass().getName());
    }
  }
}

Count: 54
                        beep : javax.swing.text.DefaultEditorKit$BeepAction
              caret-backward : javax.swing.text.DefaultEditorKit$NextVisualPositionAction
                 caret-begin : javax.swing.text.DefaultEditorKit$BeginAction
            caret-begin-line : javax.swing.text.DefaultEditorKit$BeginLineAction
       caret-begin-paragraph : javax.swing.text.DefaultEditorKit$BeginParagraphAction
            caret-begin-word : javax.swing.text.DefaultEditorKit$BeginWordAction
                  caret-down : javax.swing.text.DefaultEditorKit$NextVisualPositionAction
                   caret-end : javax.swing.text.DefaultEditorKit$EndAction
              caret-end-line : javax.swing.text.DefaultEditorKit$EndLineAction
         caret-end-paragraph : javax.swing.text.DefaultEditorKit$EndParagraphAction
              caret-end-word : javax.swing.text.DefaultEditorKit$EndWordAction
               caret-forward : javax.swing.text.DefaultEditorKit$NextVisualPositionAction
             caret-next-word : javax.swing.text.DefaultEditorKit$NextWordAction
         caret-previous-word : javax.swing.text.DefaultEditorKit$PreviousWordAction
                    caret-up : javax.swing.text.DefaultEditorKit$NextVisualPositionAction
           copy-to-clipboard : javax.swing.text.DefaultEditorKit$CopyAction
            cut-to-clipboard : javax.swing.text.DefaultEditorKit$CutAction
               default-typed : javax.swing.text.DefaultEditorKit$DefaultKeyTypedAction
                 delete-next : javax.swing.text.DefaultEditorKit$DeleteNextCharAction
             delete-previous : javax.swing.text.DefaultEditorKit$DeletePrevCharAction
                  dump-model : javax.swing.text.DefaultEditorKit$DumpModelAction
                insert-break : javax.swing.text.DefaultEditorKit$InsertBreakAction
              insert-content : javax.swing.text.DefaultEditorKit$InsertContentAction
                  insert-tab : javax.swing.text.DefaultEditorKit$InsertTabAction
         notify-field-accept : javax.swing.JTextField$NotifyAction
                   page-down : javax.swing.text.DefaultEditorKit$VerticalPageAction
                     page-up : javax.swing.text.DefaultEditorKit$VerticalPageAction
        paste-from-clipboard : javax.swing.text.DefaultEditorKit$PasteAction
                  select-all : javax.swing.text.DefaultEditorKit$SelectAllAction
                 select-line : javax.swing.text.DefaultEditorKit$SelectLineAction
            select-paragraph : javax.swing.text.DefaultEditorKit$SelectParagraphAction
                 select-word : javax.swing.text.DefaultEditorKit$SelectWordAction
          selection-backward : javax.swing.text.DefaultEditorKit$NextVisualPositionAction
             selection-begin : javax.swing.text.DefaultEditorKit$BeginAction
        selection-begin-line : javax.swing.text.DefaultEditorKit$BeginLineAction
   selection-begin-paragraph : javax.swing.text.DefaultEditorKit$BeginParagraphAction
        selection-begin-word : javax.swing.text.DefaultEditorKit$BeginWordAction
              selection-down : javax.swing.text.DefaultEditorKit$NextVisualPositionAction
               selection-end : javax.swing.text.DefaultEditorKit$EndAction
          selection-end-line : javax.swing.text.DefaultEditorKit$EndLineAction
     selection-end-paragraph : javax.swing.text.DefaultEditorKit$EndParagraphAction
          selection-end-word : javax.swing.text.DefaultEditorKit$EndWordAction
           selection-forward : javax.swing.text.DefaultEditorKit$NextVisualPositionAction
         selection-next-word : javax.swing.text.DefaultEditorKit$NextWordAction
         selection-page-down : javax.swing.text.DefaultEditorKit$VerticalPageAction
         selection-page-left : javax.swing.text.DefaultEditorKit$PageAction
        selection-page-right : javax.swing.text.DefaultEditorKit$PageAction
           selection-page-up : javax.swing.text.DefaultEditorKit$VerticalPageAction
     selection-previous-word : javax.swing.text.DefaultEditorKit$PreviousWordAction
                selection-up : javax.swing.text.DefaultEditorKit$NextVisualPositionAction
               set-read-only : javax.swing.text.DefaultEditorKit$ReadOnlyAction
                set-writable : javax.swing.text.DefaultEditorKit$WritableAction
 toggle-componentOrientation : javax.swing.text.DefaultEditorKit$ToggleComponentOrientationAction
                    unselect : javax.swing.text.DefaultEditorKit$UnselectAction

Using JLabel Mnemonics: Interconnect a specific JLabel and JTextField

import java.awt.BorderLayout;
import java.awt.event.KeyEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class LabelSampleLabelFor {
  public static void main(String args[]) {
    JFrame frame = new JFrame("Label Focus Example");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JPanel panel = new JPanel(new BorderLayout());
    JLabel label = new JLabel("Name: ");
    label.setDisplayedMnemonic(KeyEvent.VK_N);
    JTextField textField = new JTextField();
    label.setLabelFor(textField);
    panel.add(label, BorderLayout.WEST);
    panel.add(textField, BorderLayout.CENTER);
    frame.add(panel, BorderLayout.NORTH);
    frame.add(new JButton("Somewhere Else"), BorderLayout.SOUTH);
    frame.setSize(250, 150);
    frame.setVisible(true);
  }
}

Verifying Input During Focus Traversal

import java.awt.BorderLayout;
import javax.swing.InputVerifier;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JTextField;
public class VerifierSample {
  public static void main(String args[]) {
    JFrame frame = new JFrame("Verifier Sample");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JTextField textField1 = new JTextField();
    JTextField textField2 = new JTextField();
    InputVerifier verifier = new InputVerifier() {
      public boolean verify(JComponent comp) {
        boolean returnValue;
        JTextField textField = (JTextField) comp;
        try {
          Integer.parseInt(textField.getText());
          returnValue = true;
        } catch (NumberFormatException e) {
          returnValue = false;
        }
        return returnValue;
      }
    };
    textField1.setInputVerifier(verifier);
    frame.add(textField1, BorderLayout.NORTH);
    frame.add(textField2, BorderLayout.CENTER);
    frame.setSize(300, 100);
    frame.setVisible(true);
  }
}