1 /*
   2  * Copyright (c) 1995, 2013, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 package java.awt;
  26 
  27 import java.awt.peer.TextFieldPeer;
  28 import java.awt.event.*;
  29 import java.util.EventListener;
  30 import java.io.ObjectOutputStream;
  31 import java.io.ObjectInputStream;
  32 import java.io.IOException;
  33 import javax.accessibility.*;
  34 
  35 
  36 /**
  37  * A <code>TextField</code> object is a text component
  38  * that allows for the editing of a single line of text.
  39  * <p>
  40  * For example, the following image depicts a frame with four
  41  * text fields of varying widths. Two of these text fields
  42  * display the predefined text <code>"Hello"</code>.
  43  * <p>
  44  * <img src="doc-files/TextField-1.gif" alt="The preceding text describes this image."
  45  * style="float:center; margin: 7px 10px;">
  46  * <p>
  47  * Here is the code that produces these four text fields:
  48  *
  49  * <hr><blockquote><pre>
  50  * TextField tf1, tf2, tf3, tf4;
  51  * // a blank text field
  52  * tf1 = new TextField();
  53  * // blank field of 20 columns
  54  * tf2 = new TextField("", 20);
  55  * // predefined text displayed
  56  * tf3 = new TextField("Hello!");
  57  * // predefined text in 30 columns
  58  * tf4 = new TextField("Hello", 30);
  59  * </pre></blockquote><hr>
  60  * <p>
  61  * Every time the user types a key in the text field, one or
  62  * more key events are sent to the text field.  A <code>KeyEvent</code>
  63  * may be one of three types: keyPressed, keyReleased, or keyTyped.
  64  * The properties of a key event indicate which of these types
  65  * it is, as well as additional information about the event,
  66  * such as what modifiers are applied to the key event and the
  67  * time at which the event occurred.
  68  * <p>
  69  * The key event is passed to every <code>KeyListener</code>
  70  * or <code>KeyAdapter</code> object which registered to receive such
  71  * events using the component's <code>addKeyListener</code> method.
  72  * (<code>KeyAdapter</code> objects implement the
  73  * <code>KeyListener</code> interface.)
  74  * <p>
  75  * It is also possible to fire an <code>ActionEvent</code>.
  76  * If action events are enabled for the text field, they may
  77  * be fired by pressing the <code>Return</code> key.
  78  * <p>
  79  * The <code>TextField</code> class's <code>processEvent</code>
  80  * method examines the action event and passes it along to
  81  * <code>processActionEvent</code>. The latter method redirects the
  82  * event to any <code>ActionListener</code> objects that have
  83  * registered to receive action events generated by this
  84  * text field.
  85  *
  86  * @author      Sami Shaio
  87  * @see         java.awt.event.KeyEvent
  88  * @see         java.awt.event.KeyAdapter
  89  * @see         java.awt.event.KeyListener
  90  * @see         java.awt.event.ActionEvent
  91  * @see         java.awt.Component#addKeyListener
  92  * @see         java.awt.TextField#processEvent
  93  * @see         java.awt.TextField#processActionEvent
  94  * @see         java.awt.TextField#addActionListener
  95  * @since       JDK1.0
  96  */
  97 public class TextField extends TextComponent {
  98 
  99     /**
 100      * The number of columns in the text field.
 101      * A column is an approximate average character
 102      * width that is platform-dependent.
 103      * Guaranteed to be non-negative.
 104      *
 105      * @serial
 106      * @see #setColumns(int)
 107      * @see #getColumns()
 108      */
 109     int columns;
 110 
 111     /**
 112      * The echo character, which is used when
 113      * the user wishes to disguise the characters
 114      * typed into the text field.
 115      * The disguises are removed if echoChar = <code>0</code>.
 116      *
 117      * @serial
 118      * @see #getEchoChar()
 119      * @see #setEchoChar(char)
 120      * @see #echoCharIsSet()
 121      */
 122     char echoChar;
 123 
 124     transient ActionListener actionListener;
 125 
 126     private static final String base = "textfield";
 127     private static int nameCounter = 0;
 128 
 129     /*
 130      * JDK 1.1 serialVersionUID
 131      */
 132     private static final long serialVersionUID = -2966288784432217853L;
 133 
 134     /**
 135      * Initialize JNI field and method ids
 136      */
 137     private static native void initIDs();
 138 
 139     static {
 140         /* ensure that the necessary native libraries are loaded */
 141         Toolkit.loadLibraries();
 142         if (!GraphicsEnvironment.isHeadless()) {
 143             initIDs();
 144         }
 145     }
 146 
 147     /**
 148      * Constructs a new text field.
 149      * @exception HeadlessException if GraphicsEnvironment.isHeadless()
 150      * returns true.
 151      * @see java.awt.GraphicsEnvironment#isHeadless
 152      */
 153     public TextField() throws HeadlessException {
 154         this("", 0);
 155     }
 156 
 157     /**
 158      * Constructs a new text field initialized with the specified text.
 159      * @param      text       the text to be displayed. If
 160      *             <code>text</code> is <code>null</code>, the empty
 161      *             string <code>""</code> will be displayed.
 162      * @exception HeadlessException if GraphicsEnvironment.isHeadless()
 163      * returns true.
 164      * @see java.awt.GraphicsEnvironment#isHeadless
 165      */
 166     public TextField(String text) throws HeadlessException {
 167         this(text, (text != null) ? text.length() : 0);
 168     }
 169 
 170     /**
 171      * Constructs a new empty text field with the specified number
 172      * of columns.  A column is an approximate average character
 173      * width that is platform-dependent.
 174      * @param      columns     the number of columns.  If
 175      *             <code>columns</code> is less than <code>0</code>,
 176      *             <code>columns</code> is set to <code>0</code>.
 177      * @exception HeadlessException if GraphicsEnvironment.isHeadless()
 178      * returns true.
 179      * @see java.awt.GraphicsEnvironment#isHeadless
 180      */
 181     public TextField(int columns) throws HeadlessException {
 182         this("", columns);
 183     }
 184 
 185     /**
 186      * Constructs a new text field initialized with the specified text
 187      * to be displayed, and wide enough to hold the specified
 188      * number of columns. A column is an approximate average character
 189      * width that is platform-dependent.
 190      * @param      text       the text to be displayed. If
 191      *             <code>text</code> is <code>null</code>, the empty
 192      *             string <code>""</code> will be displayed.
 193      * @param      columns     the number of columns.  If
 194      *             <code>columns</code> is less than <code>0</code>,
 195      *             <code>columns</code> is set to <code>0</code>.
 196      * @exception HeadlessException if GraphicsEnvironment.isHeadless()
 197      * returns true.
 198      * @see java.awt.GraphicsEnvironment#isHeadless
 199      */
 200     public TextField(String text, int columns) throws HeadlessException {
 201         super(text);
 202         this.columns = (columns >= 0) ? columns : 0;
 203     }
 204 
 205     /**
 206      * Construct a name for this component.  Called by getName() when the
 207      * name is null.
 208      */
 209     String constructComponentName() {
 210         synchronized (TextField.class) {
 211             return base + nameCounter++;
 212         }
 213     }
 214 
 215     /**
 216      * Creates the TextField's peer.  The peer allows us to modify the
 217      * appearance of the TextField without changing its functionality.
 218      */
 219     public void addNotify() {
 220         synchronized (getTreeLock()) {
 221             if (peer == null)
 222                 peer = getToolkit().createTextField(this);
 223             super.addNotify();
 224         }
 225     }
 226 
 227     /**
 228      * Gets the character that is to be used for echoing.
 229      * <p>
 230      * An echo character is useful for text fields where
 231      * user input should not be echoed to the screen, as in
 232      * the case of a text field for entering a password.
 233      * If <code>echoChar</code> = <code>0</code>, user
 234      * input is echoed to the screen unchanged.
 235      * <p>
 236      * A Java platform implementation may support only a limited,
 237      * non-empty set of echo characters. This function returns the
 238      * echo character originally requested via setEchoChar(). The echo
 239      * character actually used by the TextField implementation might be
 240      * different.
 241      * @return      the echo character for this text field.
 242      * @see         java.awt.TextField#echoCharIsSet
 243      * @see         java.awt.TextField#setEchoChar
 244      */
 245     public char getEchoChar() {
 246         return echoChar;
 247     }
 248 
 249     /**
 250      * Sets the echo character for this text field.
 251      * <p>
 252      * An echo character is useful for text fields where
 253      * user input should not be echoed to the screen, as in
 254      * the case of a text field for entering a password.
 255      * Setting <code>echoChar</code> = <code>0</code> allows
 256      * user input to be echoed to the screen again.
 257      * <p>
 258      * A Java platform implementation may support only a limited,
 259      * non-empty set of echo characters. Attempts to set an
 260      * unsupported echo character will cause the default echo
 261      * character to be used instead. Subsequent calls to getEchoChar()
 262      * will return the echo character originally requested. This might
 263      * or might not be identical to the echo character actually
 264      * used by the TextField implementation.
 265      * @param       c   the echo character for this text field.
 266      * @see         java.awt.TextField#echoCharIsSet
 267      * @see         java.awt.TextField#getEchoChar
 268      * @since       JDK1.1
 269      */
 270     public void setEchoChar(char c) {
 271         setEchoCharacter(c);
 272     }
 273 
 274     /**
 275      * @deprecated As of JDK version 1.1,
 276      * replaced by <code>setEchoChar(char)</code>.
 277      */
 278     @Deprecated
 279     public synchronized void setEchoCharacter(char c) {
 280         if (echoChar != c) {
 281             echoChar = c;
 282             TextFieldPeer peer = (TextFieldPeer)this.peer;
 283             if (peer != null) {
 284                 peer.setEchoChar(c);
 285             }
 286         }
 287     }
 288 
 289     /**
 290      * Sets the text that is presented by this
 291      * text component to be the specified text.
 292      * @param       t   the new text.
 293      * @see         java.awt.TextComponent#getText
 294      */
 295     public void setText(String t) {
 296         super.setText(t);
 297 
 298         // This could change the preferred size of the Component.
 299         invalidateIfValid();
 300     }
 301 
 302     /**
 303      * Indicates whether or not this text field has a
 304      * character set for echoing.
 305      * <p>
 306      * An echo character is useful for text fields where
 307      * user input should not be echoed to the screen, as in
 308      * the case of a text field for entering a password.
 309      * @return     <code>true</code> if this text field has
 310      *                 a character set for echoing;
 311      *                 <code>false</code> otherwise.
 312      * @see        java.awt.TextField#setEchoChar
 313      * @see        java.awt.TextField#getEchoChar
 314      */
 315     public boolean echoCharIsSet() {
 316         return echoChar != 0;
 317     }
 318 
 319     /**
 320      * Gets the number of columns in this text field. A column is an
 321      * approximate average character width that is platform-dependent.
 322      * @return     the number of columns.
 323      * @see        java.awt.TextField#setColumns
 324      * @since      JDK1.1
 325      */
 326     public int getColumns() {
 327         return columns;
 328     }
 329 
 330     /**
 331      * Sets the number of columns in this text field. A column is an
 332      * approximate average character width that is platform-dependent.
 333      * @param      columns   the number of columns.
 334      * @see        java.awt.TextField#getColumns
 335      * @exception  IllegalArgumentException   if the value
 336      *                 supplied for <code>columns</code>
 337      *                 is less than <code>0</code>.
 338      * @since      JDK1.1
 339      */
 340     public void setColumns(int columns) {
 341         int oldVal;
 342         synchronized (this) {
 343             oldVal = this.columns;
 344             if (columns < 0) {
 345                 throw new IllegalArgumentException("columns less than zero.");
 346             }
 347             if (columns != oldVal) {
 348                 this.columns = columns;
 349             }
 350         }
 351 
 352         if (columns != oldVal) {
 353             invalidate();
 354         }
 355     }
 356 
 357     /**
 358      * Gets the preferred size of this text field
 359      * with the specified number of columns.
 360      * @param     columns the number of columns
 361      *                 in this text field.
 362      * @return    the preferred dimensions for
 363      *                 displaying this text field.
 364      * @since     JDK1.1
 365      */
 366     public Dimension getPreferredSize(int columns) {
 367         return preferredSize(columns);
 368     }
 369 
 370     /**
 371      * @deprecated As of JDK version 1.1,
 372      * replaced by <code>getPreferredSize(int)</code>.
 373      */
 374     @Deprecated
 375     public Dimension preferredSize(int columns) {
 376         synchronized (getTreeLock()) {
 377             TextFieldPeer peer = (TextFieldPeer)this.peer;
 378             return (peer != null) ?
 379                        peer.getPreferredSize(columns) :
 380                        super.preferredSize();
 381         }
 382     }
 383 
 384     /**
 385      * Gets the preferred size of this text field.
 386      * @return     the preferred dimensions for
 387      *                         displaying this text field.
 388      * @since      JDK1.1
 389      */
 390     public Dimension getPreferredSize() {
 391         return preferredSize();
 392     }
 393 
 394     /**
 395      * @deprecated As of JDK version 1.1,
 396      * replaced by <code>getPreferredSize()</code>.
 397      */
 398     @Deprecated
 399     public Dimension preferredSize() {
 400         synchronized (getTreeLock()) {
 401             return (columns > 0) ?
 402                        preferredSize(columns) :
 403                        super.preferredSize();
 404         }
 405     }
 406 
 407     /**
 408      * Gets the minimum dimensions for a text field with
 409      * the specified number of columns.
 410      * @param    columns   the number of columns in
 411      *                          this text field.
 412      * @since    JDK1.1
 413      */
 414     public Dimension getMinimumSize(int columns) {
 415         return minimumSize(columns);
 416     }
 417 
 418     /**
 419      * @deprecated As of JDK version 1.1,
 420      * replaced by <code>getMinimumSize(int)</code>.
 421      */
 422     @Deprecated
 423     public Dimension minimumSize(int columns) {
 424         synchronized (getTreeLock()) {
 425             TextFieldPeer peer = (TextFieldPeer)this.peer;
 426             return (peer != null) ?
 427                        peer.getMinimumSize(columns) :
 428                        super.minimumSize();
 429         }
 430     }
 431 
 432     /**
 433      * Gets the minimum dimensions for this text field.
 434      * @return     the minimum dimensions for
 435      *                  displaying this text field.
 436      * @since      JDK1.1
 437      */
 438     public Dimension getMinimumSize() {
 439         return minimumSize();
 440     }
 441 
 442     /**
 443      * @deprecated As of JDK version 1.1,
 444      * replaced by <code>getMinimumSize()</code>.
 445      */
 446     @Deprecated
 447     public Dimension minimumSize() {
 448         synchronized (getTreeLock()) {
 449             return (columns > 0) ?
 450                        minimumSize(columns) :
 451                        super.minimumSize();
 452         }
 453     }
 454 
 455     /**
 456      * Adds the specified action listener to receive
 457      * action events from this text field.
 458      * If l is null, no exception is thrown and no action is performed.
 459      * <p>Refer to <a href="doc-files/AWTThreadIssues.html#ListenersThreads"
 460      * >AWT Threading Issues</a> for details on AWT's threading model.
 461      *
 462      * @param      l the action listener.
 463      * @see        #removeActionListener
 464      * @see        #getActionListeners
 465      * @see        java.awt.event.ActionListener
 466      * @since      JDK1.1
 467      */
 468     public synchronized void addActionListener(ActionListener l) {
 469         if (l == null) {
 470             return;
 471         }
 472         actionListener = AWTEventMulticaster.add(actionListener, l);
 473         newEventsOnly = true;
 474     }
 475 
 476     /**
 477      * Removes the specified action listener so that it no longer
 478      * receives action events from this text field.
 479      * If l is null, no exception is thrown and no action is performed.
 480      * <p>Refer to <a href="doc-files/AWTThreadIssues.html#ListenersThreads"
 481      * >AWT Threading Issues</a> for details on AWT's threading model.
 482      *
 483      * @param           l the action listener.
 484      * @see             #addActionListener
 485      * @see             #getActionListeners
 486      * @see             java.awt.event.ActionListener
 487      * @since           JDK1.1
 488      */
 489     public synchronized void removeActionListener(ActionListener l) {
 490         if (l == null) {
 491             return;
 492         }
 493         actionListener = AWTEventMulticaster.remove(actionListener, l);
 494     }
 495 
 496     /**
 497      * Returns an array of all the action listeners
 498      * registered on this textfield.
 499      *
 500      * @return all of this textfield's <code>ActionListener</code>s
 501      *         or an empty array if no action
 502      *         listeners are currently registered
 503      *
 504      * @see #addActionListener
 505      * @see #removeActionListener
 506      * @see java.awt.event.ActionListener
 507      * @since 1.4
 508      */
 509     public synchronized ActionListener[] getActionListeners() {
 510         return getListeners(ActionListener.class);
 511     }
 512 
 513     /**
 514      * Returns an array of all the objects currently registered
 515      * as <code><em>Foo</em>Listener</code>s
 516      * upon this <code>TextField</code>.
 517      * <code><em>Foo</em>Listener</code>s are registered using the
 518      * <code>add<em>Foo</em>Listener</code> method.
 519      *
 520      * <p>
 521      * You can specify the <code>listenerType</code> argument
 522      * with a class literal, such as
 523      * <code><em>Foo</em>Listener.class</code>.
 524      * For example, you can query a
 525      * <code>TextField</code> <code>t</code>
 526      * for its action listeners with the following code:
 527      *
 528      * <pre>ActionListener[] als = (ActionListener[])(t.getListeners(ActionListener.class));</pre>
 529      *
 530      * If no such listeners exist, this method returns an empty array.
 531      *
 532      * @param listenerType the type of listeners requested; this parameter
 533      *          should specify an interface that descends from
 534      *          <code>java.util.EventListener</code>
 535      * @return an array of all objects registered as
 536      *          <code><em>Foo</em>Listener</code>s on this textfield,
 537      *          or an empty array if no such
 538      *          listeners have been added
 539      * @exception ClassCastException if <code>listenerType</code>
 540      *          doesn't specify a class or interface that implements
 541      *          <code>java.util.EventListener</code>
 542      *
 543      * @see #getActionListeners
 544      * @since 1.3
 545      */
 546     public <T extends EventListener> T[] getListeners(Class<T> listenerType) {
 547         EventListener l = null;
 548         if  (listenerType == ActionListener.class) {
 549             l = actionListener;
 550         } else {
 551             return super.getListeners(listenerType);
 552         }
 553         return AWTEventMulticaster.getListeners(l, listenerType);
 554     }
 555 
 556     // REMIND: remove when filtering is done at lower level
 557     boolean eventEnabled(AWTEvent e) {
 558         if (e.id == ActionEvent.ACTION_PERFORMED) {
 559             if ((eventMask & AWTEvent.ACTION_EVENT_MASK) != 0 ||
 560                 actionListener != null) {
 561                 return true;
 562             }
 563             return false;
 564         }
 565         return super.eventEnabled(e);
 566     }
 567 
 568     /**
 569      * Processes events on this text field. If the event
 570      * is an instance of <code>ActionEvent</code>,
 571      * it invokes the <code>processActionEvent</code>
 572      * method. Otherwise, it invokes <code>processEvent</code>
 573      * on the superclass.
 574      * <p>Note that if the event parameter is <code>null</code>
 575      * the behavior is unspecified and may result in an
 576      * exception.
 577      *
 578      * @param      e the event
 579      * @see        java.awt.event.ActionEvent
 580      * @see        java.awt.TextField#processActionEvent
 581      * @since      JDK1.1
 582      */
 583     protected void processEvent(AWTEvent e) {
 584         if (e instanceof ActionEvent) {
 585             processActionEvent((ActionEvent)e);
 586             return;
 587         }
 588         super.processEvent(e);
 589     }
 590 
 591     /**
 592      * Processes action events occurring on this text field by
 593      * dispatching them to any registered
 594      * <code>ActionListener</code> objects.
 595      * <p>
 596      * This method is not called unless action events are
 597      * enabled for this component. Action events are enabled
 598      * when one of the following occurs:
 599      * <ul>
 600      * <li>An <code>ActionListener</code> object is registered
 601      * via <code>addActionListener</code>.
 602      * <li>Action events are enabled via <code>enableEvents</code>.
 603      * </ul>
 604      * <p>Note that if the event parameter is <code>null</code>
 605      * the behavior is unspecified and may result in an
 606      * exception.
 607      *
 608      * @param       e the action event
 609      * @see         java.awt.event.ActionListener
 610      * @see         java.awt.TextField#addActionListener
 611      * @see         java.awt.Component#enableEvents
 612      * @since       JDK1.1
 613      */
 614     protected void processActionEvent(ActionEvent e) {
 615         ActionListener listener = actionListener;
 616         if (listener != null) {
 617             listener.actionPerformed(e);
 618         }
 619     }
 620 
 621     /**
 622      * Returns a string representing the state of this <code>TextField</code>.
 623      * This method is intended to be used only for debugging purposes, and the
 624      * content and format of the returned string may vary between
 625      * implementations. The returned string may be empty but may not be
 626      * <code>null</code>.
 627      *
 628      * @return      the parameter string of this text field
 629      */
 630     protected String paramString() {
 631         String str = super.paramString();
 632         if (echoChar != 0) {
 633             str += ",echo=" + echoChar;
 634         }
 635         return str;
 636     }
 637 
 638 
 639     /*
 640      * Serialization support.
 641      */
 642     /**
 643      * The textField Serialized Data Version.
 644      *
 645      * @serial
 646      */
 647     private int textFieldSerializedDataVersion = 1;
 648 
 649     /**
 650      * Writes default serializable fields to stream.  Writes
 651      * a list of serializable ActionListener(s) as optional data.
 652      * The non-serializable ActionListener(s) are detected and
 653      * no attempt is made to serialize them.
 654      *
 655      * @serialData Null terminated sequence of zero or more pairs.
 656      *             A pair consists of a String and Object.
 657      *             The String indicates the type of object and
 658      *             is one of the following :
 659      *             ActionListenerK indicating and ActionListener object.
 660      *
 661      * @see AWTEventMulticaster#save(ObjectOutputStream, String, EventListener)
 662      * @see java.awt.Component#actionListenerK
 663      */
 664     private void writeObject(ObjectOutputStream s)
 665       throws IOException
 666     {
 667         s.defaultWriteObject();
 668 
 669         AWTEventMulticaster.save(s, actionListenerK, actionListener);
 670         s.writeObject(null);
 671     }
 672 
 673     /**
 674      * Read the ObjectInputStream and if it isn't null,
 675      * add a listener to receive action events fired by the
 676      * TextField.  Unrecognized keys or values will be
 677      * ignored.
 678      *
 679      * @exception HeadlessException if
 680      * <code>GraphicsEnvironment.isHeadless()</code> returns
 681      * <code>true</code>
 682      * @see #removeActionListener(ActionListener)
 683      * @see #addActionListener(ActionListener)
 684      * @see java.awt.GraphicsEnvironment#isHeadless
 685      */
 686     private void readObject(ObjectInputStream s)
 687       throws ClassNotFoundException, IOException, HeadlessException
 688     {
 689         // HeadlessException will be thrown by TextComponent's readObject
 690         s.defaultReadObject();
 691 
 692         // Make sure the state we just read in for columns has legal values
 693         if (columns < 0) {
 694             columns = 0;
 695         }
 696 
 697         // Read in listeners, if any
 698         Object keyOrNull;
 699         while(null != (keyOrNull = s.readObject())) {
 700             String key = ((String)keyOrNull).intern();
 701 
 702             if (actionListenerK == key) {
 703                 addActionListener((ActionListener)(s.readObject()));
 704             } else {
 705                 // skip value for unrecognized key
 706                 s.readObject();
 707             }
 708         }
 709     }
 710 
 711 
 712 /////////////////
 713 // Accessibility support
 714 ////////////////
 715 
 716 
 717     /**
 718      * Gets the AccessibleContext associated with this TextField.
 719      * For text fields, the AccessibleContext takes the form of an
 720      * AccessibleAWTTextField.
 721      * A new AccessibleAWTTextField instance is created if necessary.
 722      *
 723      * @return an AccessibleAWTTextField that serves as the
 724      *         AccessibleContext of this TextField
 725      * @since 1.3
 726      */
 727     public AccessibleContext getAccessibleContext() {
 728         if (accessibleContext == null) {
 729             accessibleContext = new AccessibleAWTTextField();
 730         }
 731         return accessibleContext;
 732     }
 733 
 734     /**
 735      * This class implements accessibility support for the
 736      * <code>TextField</code> class.  It provides an implementation of the
 737      * Java Accessibility API appropriate to text field user-interface elements.
 738      * @since 1.3
 739      */
 740     protected class AccessibleAWTTextField extends AccessibleAWTTextComponent
 741     {
 742         /*
 743          * JDK 1.3 serialVersionUID
 744          */
 745         private static final long serialVersionUID = 6219164359235943158L;
 746 
 747         /**
 748          * Gets the state set of this object.
 749          *
 750          * @return an instance of AccessibleStateSet describing the states
 751          * of the object
 752          * @see AccessibleState
 753          */
 754         public AccessibleStateSet getAccessibleStateSet() {
 755             AccessibleStateSet states = super.getAccessibleStateSet();
 756             states.add(AccessibleState.SINGLE_LINE);
 757             return states;
 758         }
 759     }
 760 
 761 }