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1: /* Preferences -- Preference node containing key value entries and subnodes 2: Copyright (C) 2001, 2004, 2005, 2006 Free Software Foundation, Inc. 3: 4: This file is part of GNU Classpath. 5: 6: GNU Classpath is free software; you can redistribute it and/or modify 7: it under the terms of the GNU General Public License as published by 8: the Free Software Foundation; either version 2, or (at your option) 9: any later version. 10: 11: GNU Classpath is distributed in the hope that it will be useful, but 12: WITHOUT ANY WARRANTY; without even the implied warranty of 13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14: General Public License for more details. 15: 16: You should have received a copy of the GNU General Public License 17: along with GNU Classpath; see the file COPYING. If not, write to the 18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19: 02110-1301 USA. 20: 21: Linking this library statically or dynamically with other modules is 22: making a combined work based on this library. Thus, the terms and 23: conditions of the GNU General Public License cover the whole 24: combination. 25: 26: As a special exception, the copyright holders of this library give you 27: permission to link this library with independent modules to produce an 28: executable, regardless of the license terms of these independent 29: modules, and to copy and distribute the resulting executable under 30: terms of your choice, provided that you also meet, for each linked 31: independent module, the terms and conditions of the license of that 32: module. An independent module is a module which is not derived from 33: or based on this library. If you modify this library, you may extend 34: this exception to your version of the library, but you are not 35: obligated to do so. If you do not wish to do so, delete this 36: exception statement from your version. */ 37: 38: package java.util.prefs; 39: 40: import gnu.classpath.ServiceFactory; 41: import gnu.java.util.prefs.NodeReader; 42: 43: import java.io.IOException; 44: import java.io.InputStream; 45: import java.io.OutputStream; 46: import java.security.AccessController; 47: import java.security.Permission; 48: import java.security.PrivilegedAction; 49: import java.util.Iterator; 50: 51: /** 52: * Preference node containing key value entries and subnodes. 53: * <p> 54: * There are two preference node trees, a system tree which can be accessed 55: * by calling <code>systemRoot()</code> containing system preferences usefull 56: * for all users, and a user tree that can be accessed by calling 57: * <code>userRoot()</code> containing preferences that can differ between 58: * different users. How different users are identified is implementation 59: * depended. It can be determined by Thread, Access Control Context or Subject. 60: * <p> 61: * This implementation uses the "java.util.prefs.PreferencesFactory" system 62: * property to find a class that implement <code>PreferencesFactory</code> 63: * and initialized that class (if it has a public no arguments contructor) 64: * to get at the actual system or user root. If the system property is not set, 65: * or the class cannot be initialized it uses the default implementation 66: * <code>gnu.java.util.prefs.FileBasedFactory</code>. 67: * <p> 68: * Besides the two static method above to get the roots of the system and user 69: * preference node trees there are also two convenience methods to access the 70: * default preference node for a particular package an object is in. These are 71: * <code>userNodeForPackage()</code> and <code>systemNodeForPackage()</code>. 72: * Both methods take an Object as an argument so accessing preferences values 73: * can be as easy as calling <code>Preferences.userNodeForPackage(this)</code>. 74: * <p> 75: * Note that if a security manager is installed all static methods check for 76: * <code>RuntimePermission("preferences")</code>. But if this permission is 77: * given to the code then it can access and change all (user) preference nodes 78: * and entries. So you should be carefull not to store to sensitive information 79: * or make security decissions based on preference values since there is no 80: * more fine grained control over what preference values can be changed once 81: * code has been given the correct runtime permission. 82: * <p> 83: * XXX 84: * 85: * @since 1.4 86: * @author Mark Wielaard (mark@klomp.org) 87: */ 88: public abstract class Preferences { 89: 90: // Static Fields 91: 92: /** 93: * Default PreferencesFactory class used when the system property 94: * "java.util.prefs.PreferencesFactory" is not set. 95: */ 96: private static final String defaultFactoryClass 97: = "gnu.java.util.prefs.FileBasedFactory"; 98: 99: /** Permission needed to access system or user root. */ 100: private static final Permission prefsPermission 101: = new RuntimePermission("preferences"); 102: 103: /** 104: * The preferences factory object that supplies the system and user root. 105: * Set and returned by the getFactory() method. 106: */ 107: private static PreferencesFactory factory; 108: 109: /** Maximum node name length. 80 characters. */ 110: public static final int MAX_NAME_LENGTH = 80; 111: 112: /** Maximum entry key length. 80 characters. */ 113: public static final int MAX_KEY_LENGTH = 80; 114: 115: /** Maximum entry value length. 8192 characters. */ 116: public static final int MAX_VALUE_LENGTH = 8192; 117: 118: // Constructors 119: 120: /** 121: * Creates a new Preferences node. Can only be used by subclasses. 122: * Empty implementation. 123: */ 124: protected Preferences() {} 125: 126: // Static methods 127: 128: /** 129: * Returns the system preferences root node containing usefull preferences 130: * for all users. It is save to cache this value since it should always 131: * return the same preference node. 132: * 133: * @return the root system preference node 134: * @exception SecurityException when a security manager is installed and 135: * the caller does not have <code>RuntimePermission("preferences")</code>. 136: */ 137: public static Preferences systemRoot() throws SecurityException { 138: // Get the preferences factory and check for permission 139: PreferencesFactory factory = getFactory(); 140: 141: return factory.systemRoot(); 142: } 143: 144: /** 145: * Returns the user preferences root node containing preferences for the 146: * the current user. How different users are identified is implementation 147: * depended. It can be determined by Thread, Access Control Context or 148: * Subject. 149: * 150: * @return the root user preference node 151: * @exception SecurityException when a security manager is installed and 152: * the caller does not have <code>RuntimePermission("preferences")</code>. 153: */ 154: public static Preferences userRoot() throws SecurityException { 155: // Get the preferences factory and check for permission 156: PreferencesFactory factory = getFactory(); 157: return factory.userRoot(); 158: } 159: 160: /** 161: * Private helper method for <code>systemRoot()</code> and 162: * <code>userRoot()</code>. Checks security permission and instantiates the 163: * correct factory if it has not yet been set. 164: * <p> 165: * When the preferences factory has not yet been set this method first 166: * tries to get the system propery "java.util.prefs.PreferencesFactory" 167: * and tries to initializes that class. If the system property is not set 168: * or initialization fails it returns an instance of the default factory 169: * <code>gnu.java.util.prefs.FileBasedPreferencesFactory</code>. 170: * 171: * @return the preferences factory to use 172: * @exception SecurityException when a security manager is installed and 173: * the caller does not have <code>RuntimePermission("preferences")</code>. 174: */ 175: private static PreferencesFactory getFactory() throws SecurityException { 176: 177: // First check for permission 178: SecurityManager sm = System.getSecurityManager(); 179: if (sm != null) { 180: sm.checkPermission(prefsPermission); 181: } 182: 183: // Get the factory 184: if (factory == null) { 185: // Caller might not have enough permissions 186: factory = AccessController.doPrivileged( 187: new PrivilegedAction<PreferencesFactory>() { 188: public PreferencesFactory run() { 189: PreferencesFactory pf = null; 190: String className = System.getProperty 191: ("java.util.prefs.PreferencesFactory"); 192: if (className != null) { 193: try { 194: Class fc = Class.forName(className); 195: Object o = fc.newInstance(); 196: pf = (PreferencesFactory) o; 197: } catch (ClassNotFoundException cnfe) 198: {/*ignore*/} 199: catch (InstantiationException ie) 200: {/*ignore*/} 201: catch (IllegalAccessException iae) 202: {/*ignore*/} 203: catch (ClassCastException cce) 204: {/*ignore*/} 205: } 206: return pf; 207: } 208: }); 209: 210: // Still no factory? Try to see if we have one defined 211: // as a System Preference 212: if (factory == null) 213: { 214: Iterator iter = ServiceFactory.lookupProviders 215: (PreferencesFactory.class, null); 216: 217: if (iter != null && iter.hasNext()) 218: factory = (PreferencesFactory) iter.next(); 219: } 220: 221: // Still no factory? Use our default. 222: if (factory == null) 223: { 224: try 225: { 226: Class cls = Class.forName (defaultFactoryClass); 227: factory = (PreferencesFactory) cls.newInstance(); 228: } 229: catch (Exception e) 230: { 231: throw new RuntimeException ("Couldn't load default factory" 232: + " '"+ defaultFactoryClass +"'", e); 233: } 234: } 235: 236: } 237: 238: return factory; 239: } 240: 241: /** 242: * Returns the system preferences node for the package of a class. 243: * The package node name of the class is determined by dropping the 244: * final component of the fully qualified class name and 245: * changing all '.' to '/' in the package name. If the class of the 246: * object has no package then the package node name is "<unnamed>". 247: * The returned node is <code>systemRoot().node(packageNodeName)</code>. 248: * 249: * @param c Object whose default system preference node is requested 250: * @returns system preferences node that should be used by class c 251: * @exception SecurityException when a security manager is installed and 252: * the caller does not have <code>RuntimePermission("preferences")</code>. 253: */ 254: public static Preferences systemNodeForPackage(Class<?> c) 255: throws SecurityException 256: { 257: return nodeForPackage(c, systemRoot()); 258: } 259: 260: /** 261: * Returns the user preferences node for the package of a class. 262: * The package node name of the class is determined by dropping the 263: * final component of the fully qualified class name and 264: * changing all '.' to '/' in the package name. If the class of the 265: * object has no package then the package node name is "<unnamed>". 266: * The returned node is <code>userRoot().node(packageNodeName)</code>. 267: * 268: * @param c Object whose default userpreference node is requested 269: * @returns userpreferences node that should be used by class c 270: * @exception SecurityException when a security manager is installed and 271: * the caller does not have <code>RuntimePermission("preferences")</code>. 272: */ 273: public static Preferences userNodeForPackage(Class<?> c) 274: throws SecurityException 275: { 276: return nodeForPackage(c, userRoot()); 277: } 278: 279: /** 280: * Private helper method for <code>systemNodeForPackage()</code> and 281: * <code>userNodeForPackage()</code>. Given the correct system or user 282: * root it returns the correct Preference node for the package node name 283: * of the given object. 284: */ 285: private static Preferences nodeForPackage(Class c, Preferences root) { 286: // Get the package path 287: String className = c.getName(); 288: String packagePath; 289: int index = className.lastIndexOf('.'); 290: if(index == -1) { 291: packagePath = "<unnamed>"; 292: } else { 293: packagePath = className.substring(0,index).replace('.','/'); 294: } 295: 296: return root.node(packagePath); 297: } 298: 299: /** 300: * Import preferences from the given input stream. This expects 301: * preferences to be represented in XML as emitted by 302: * {@link #exportNode(OutputStream)} and 303: * {@link #exportSubtree(OutputStream)}. 304: * @throws IOException if there is an error while reading 305: * @throws InvalidPreferencesFormatException if the XML is not properly 306: * formatted 307: */ 308: public static void importPreferences(InputStream is) 309: throws InvalidPreferencesFormatException, 310: IOException 311: { 312: PreferencesFactory factory = getFactory(); 313: NodeReader reader = new NodeReader(is, factory); 314: reader.importPreferences(); 315: } 316: 317: // abstract methods (identification) 318: 319: /** 320: * Returns the absolute path name of this preference node. 321: * The absolute path name of a node is the path name of its parent node 322: * plus a '/' plus its own name. If the node is the root node and has no 323: * parent then its name is "" and its absolute path name is "/". 324: */ 325: public abstract String absolutePath(); 326: 327: /** 328: * Returns true if this node comes from the user preferences tree, false 329: * if it comes from the system preferences tree. 330: */ 331: public abstract boolean isUserNode(); 332: 333: /** 334: * Returns the name of this preferences node. The name of the node cannot 335: * be null, can be mostly 80 characters and cannot contain any '/' 336: * characters. The root node has as name "". 337: */ 338: public abstract String name(); 339: 340: /** 341: * Returns the String given by 342: * <code> 343: * (isUserNode() ? "User":"System") + " Preference Node: " + absolutePath() 344: * </code> 345: */ 346: public abstract String toString(); 347: 348: // abstract methods (navigation) 349: 350: /** 351: * Returns all the direct sub nodes of this preferences node. 352: * Needs access to the backing store to give a meaningfull answer. 353: * 354: * @exception BackingStoreException when the backing store cannot be 355: * reached 356: * @exception IllegalStateException when this node has been removed 357: */ 358: public abstract String[] childrenNames() throws BackingStoreException; 359: 360: /** 361: * Returns a sub node of this preferences node if the given path is 362: * relative (does not start with a '/') or a sub node of the root 363: * if the path is absolute (does start with a '/'). 364: * 365: * @exception IllegalStateException if this node has been removed 366: * @exception IllegalArgumentException if the path contains two or more 367: * consecutive '/' characters, ends with a '/' charactor and is not the 368: * string "/" (indicating the root node) or any name on the path is more 369: * then 80 characters long 370: */ 371: public abstract Preferences node(String path); 372: 373: /** 374: * Returns true if the node that the path points to exists in memory or 375: * in the backing store. Otherwise it returns false or an exception is 376: * thrown. When this node is removed the only valid parameter is the 377: * empty string (indicating this node), the return value in that case 378: * will be false. 379: * 380: * @exception BackingStoreException when the backing store cannot be 381: * reached 382: * @exception IllegalStateException if this node has been removed 383: * and the path is not the empty string (indicating this node) 384: * @exception IllegalArgumentException if the path contains two or more 385: * consecutive '/' characters, ends with a '/' charactor and is not the 386: * string "/" (indicating the root node) or any name on the path is more 387: * then 80 characters long 388: */ 389: public abstract boolean nodeExists(String path) 390: throws BackingStoreException; 391: 392: /** 393: * Returns the parent preferences node of this node or null if this is 394: * the root of the preferences tree. 395: * 396: * @exception IllegalStateException if this node has been removed 397: */ 398: public abstract Preferences parent(); 399: 400: // abstract methods (export) 401: 402: /** 403: * Export this node, but not its descendants, as XML to the 404: * indicated output stream. The XML will be encoded using UTF-8 405: * and will use a specified document type:<br> 406: * <code><!DOCTYPE preferences SYSTEM "http://java.sun.com/dtd/preferences.dtd"></code><br> 407: * @param os the output stream to which the XML is sent 408: * @throws BackingStoreException if preference data cannot be read 409: * @throws IOException if an error occurs while writing the XML 410: * @throws IllegalStateException if this node or an ancestor has been removed 411: */ 412: public abstract void exportNode(OutputStream os) 413: throws BackingStoreException, 414: IOException; 415: 416: /** 417: * Export this node and all its descendants as XML to the 418: * indicated output stream. The XML will be encoded using UTF-8 419: * and will use a specified document type:<br> 420: * <code><!DOCTYPE preferences SYSTEM "http://java.sun.com/dtd/preferences.dtd"></code><br> 421: * @param os the output stream to which the XML is sent 422: * @throws BackingStoreException if preference data cannot be read 423: * @throws IOException if an error occurs while writing the XML 424: * @throws IllegalStateException if this node or an ancestor has been removed 425: */ 426: public abstract void exportSubtree(OutputStream os) 427: throws BackingStoreException, 428: IOException; 429: 430: // abstract methods (preference entry manipulation) 431: 432: /** 433: * Returns an (possibly empty) array with all the keys of the preference 434: * entries of this node. 435: * 436: * @exception BackingStoreException when the backing store cannot be 437: * reached 438: * @exception IllegalStateException if this node has been removed 439: */ 440: public abstract String[] keys() throws BackingStoreException; 441: 442: /** 443: * Returns the value associated with the key in this preferences node. If 444: * the default value of the key cannot be found in the preferences node 445: * entries or something goes wrong with the backing store the supplied 446: * default value is returned. 447: * 448: * @exception IllegalArgumentException if key is larger then 80 characters 449: * @exception IllegalStateException if this node has been removed 450: * @exception NullPointerException if key is null 451: */ 452: public abstract String get(String key, String defaultVal); 453: 454: /** 455: * Convenience method for getting the given entry as a boolean. 456: * When the string representation of the requested entry is either 457: * "true" or "false" (ignoring case) then that value is returned, 458: * otherwise the given default boolean value is returned. 459: * 460: * @exception IllegalArgumentException if key is larger then 80 characters 461: * @exception IllegalStateException if this node has been removed 462: * @exception NullPointerException if key is null 463: */ 464: public abstract boolean getBoolean(String key, boolean defaultVal); 465: 466: /** 467: * Convenience method for getting the given entry as a byte array. 468: * When the string representation of the requested entry is a valid 469: * Base64 encoded string (without any other characters, such as newlines) 470: * then the decoded Base64 string is returned as byte array, 471: * otherwise the given default byte array value is returned. 472: * 473: * @exception IllegalArgumentException if key is larger then 80 characters 474: * @exception IllegalStateException if this node has been removed 475: * @exception NullPointerException if key is null 476: */ 477: public abstract byte[] getByteArray(String key, byte[] defaultVal); 478: 479: /** 480: * Convenience method for getting the given entry as a double. 481: * When the string representation of the requested entry can be decoded 482: * with <code>Double.parseDouble()</code> then that double is returned, 483: * otherwise the given default double value is returned. 484: * 485: * @exception IllegalArgumentException if key is larger then 80 characters 486: * @exception IllegalStateException if this node has been removed 487: * @exception NullPointerException if key is null 488: */ 489: public abstract double getDouble(String key, double defaultVal); 490: 491: /** 492: * Convenience method for getting the given entry as a float. 493: * When the string representation of the requested entry can be decoded 494: * with <code>Float.parseFloat()</code> then that float is returned, 495: * otherwise the given default float value is returned. 496: * 497: * @exception IllegalArgumentException if key is larger then 80 characters 498: * @exception IllegalStateException if this node has been removed 499: * @exception NullPointerException if key is null 500: */ 501: public abstract float getFloat(String key, float defaultVal); 502: 503: /** 504: * Convenience method for getting the given entry as an integer. 505: * When the string representation of the requested entry can be decoded 506: * with <code>Integer.parseInt()</code> then that integer is returned, 507: * otherwise the given default integer value is returned. 508: * 509: * @exception IllegalArgumentException if key is larger then 80 characters 510: * @exception IllegalStateException if this node has been removed 511: * @exception NullPointerException if key is null 512: */ 513: public abstract int getInt(String key, int defaultVal); 514: 515: /** 516: * Convenience method for getting the given entry as a long. 517: * When the string representation of the requested entry can be decoded 518: * with <code>Long.parseLong()</code> then that long is returned, 519: * otherwise the given default long value is returned. 520: * 521: * @exception IllegalArgumentException if key is larger then 80 characters 522: * @exception IllegalStateException if this node has been removed 523: * @exception NullPointerException if key is null 524: */ 525: public abstract long getLong(String key, long defaultVal); 526: 527: /** 528: * Sets the value of the given preferences entry for this node. 529: * Key and value cannot be null, the key cannot exceed 80 characters 530: * and the value cannot exceed 8192 characters. 531: * <p> 532: * The result will be immediatly visible in this VM, but may not be 533: * immediatly written to the backing store. 534: * 535: * @exception NullPointerException if either key or value are null 536: * @exception IllegalArgumentException if either key or value are to large 537: * @exception IllegalStateException when this node has been removed 538: */ 539: public abstract void put(String key, String value); 540: 541: /** 542: * Convenience method for setting the given entry as a boolean. 543: * The boolean is converted with <code>Boolean.toString(value)</code> 544: * and then stored in the preference entry as that string. 545: * 546: * @exception NullPointerException if key is null 547: * @exception IllegalArgumentException if the key length is to large 548: * @exception IllegalStateException when this node has been removed 549: */ 550: public abstract void putBoolean(String key, boolean value); 551: 552: /** 553: * Convenience method for setting the given entry as an array of bytes. 554: * The byte array is converted to a Base64 encoded string 555: * and then stored in the preference entry as that string. 556: * <p> 557: * Note that a byte array encoded as a Base64 string will be about 1.3 558: * times larger then the original length of the byte array, which means 559: * that the byte array may not be larger about 6 KB. 560: * 561: * @exception NullPointerException if either key or value are null 562: * @exception IllegalArgumentException if either key or value are to large 563: * @exception IllegalStateException when this node has been removed 564: */ 565: public abstract void putByteArray(String key, byte[] value); 566: 567: /** 568: * Convenience method for setting the given entry as a double. 569: * The double is converted with <code>Double.toString(double)</code> 570: * and then stored in the preference entry as that string. 571: * 572: * @exception NullPointerException if the key is null 573: * @exception IllegalArgumentException if the key length is to large 574: * @exception IllegalStateException when this node has been removed 575: */ 576: public abstract void putDouble(String key, double value); 577: 578: /** 579: * Convenience method for setting the given entry as a float. 580: * The float is converted with <code>Float.toString(float)</code> 581: * and then stored in the preference entry as that string. 582: * 583: * @exception NullPointerException if the key is null 584: * @exception IllegalArgumentException if the key length is to large 585: * @exception IllegalStateException when this node has been removed 586: */ 587: public abstract void putFloat(String key, float value); 588: 589: /** 590: * Convenience method for setting the given entry as an integer. 591: * The integer is converted with <code>Integer.toString(int)</code> 592: * and then stored in the preference entry as that string. 593: * 594: * @exception NullPointerException if the key is null 595: * @exception IllegalArgumentException if the key length is to large 596: * @exception IllegalStateException when this node has been removed 597: */ 598: public abstract void putInt(String key, int value); 599: 600: /** 601: * Convenience method for setting the given entry as a long. 602: * The long is converted with <code>Long.toString(long)</code> 603: * and then stored in the preference entry as that string. 604: * 605: * @exception NullPointerException if the key is null 606: * @exception IllegalArgumentException if the key length is to large 607: * @exception IllegalStateException when this node has been removed 608: */ 609: public abstract void putLong(String key, long value); 610: 611: /** 612: * Removes the preferences entry from this preferences node. 613: * <p> 614: * The result will be immediatly visible in this VM, but may not be 615: * immediatly written to the backing store. 616: * 617: * @exception NullPointerException if the key is null 618: * @exception IllegalArgumentException if the key length is to large 619: * @exception IllegalStateException when this node has been removed 620: */ 621: public abstract void remove(String key); 622: 623: // abstract methods (preference node manipulation) 624: 625: /** 626: * Removes all entries from this preferences node. May need access to the 627: * backing store to get and clear all entries. 628: * <p> 629: * The result will be immediatly visible in this VM, but may not be 630: * immediatly written to the backing store. 631: * 632: * @exception BackingStoreException when the backing store cannot be 633: * reached 634: * @exception IllegalStateException if this node has been removed 635: */ 636: public abstract void clear() throws BackingStoreException; 637: 638: /** 639: * Writes all preference changes on this and any subnode that have not 640: * yet been written to the backing store. This has no effect on the 641: * preference entries in this VM, but it makes sure that all changes 642: * are visible to other programs (other VMs might need to call the 643: * <code>sync()</code> method to actually see the changes to the backing 644: * store. 645: * 646: * @exception BackingStoreException when the backing store cannot be 647: * reached 648: * @exception IllegalStateException if this node has been removed 649: */ 650: public abstract void flush() throws BackingStoreException; 651: 652: /** 653: * Writes and reads all preference changes to and from this and any 654: * subnodes. This makes sure that all local changes are written to the 655: * backing store and that all changes to the backing store are visible 656: * in this preference node (and all subnodes). 657: * 658: * @exception BackingStoreException when the backing store cannot be 659: * reached 660: * @exception IllegalStateException if this node has been removed 661: */ 662: public abstract void sync() throws BackingStoreException; 663: 664: /** 665: * Removes this and all subnodes from the backing store and clears all 666: * entries. After removal this instance will not be useable (except for 667: * a few methods that don't throw a <code>InvalidStateException</code>), 668: * even when a new node with the same path name is created this instance 669: * will not be usable again. The root (system or user) may never be removed. 670: * <p> 671: * Note that according to the specification an implementation may delay 672: * removal of the node from the backing store till the <code>flush()</code> 673: * method is called. But the <code>flush()</code> method may throw a 674: * <code>IllegalStateException</code> when the node has been removed. 675: * So most implementations will actually remove the node and any subnodes 676: * from the backing store immediatly. 677: * 678: * @exception BackingStoreException when the backing store cannot be 679: * reached 680: * @exception IllegalStateException if this node has already been removed 681: * @exception UnsupportedOperationException if this is a root node 682: */ 683: public abstract void removeNode() throws BackingStoreException; 684: 685: // abstract methods (listeners) 686: 687: public abstract void addNodeChangeListener(NodeChangeListener listener); 688: 689: public abstract void addPreferenceChangeListener 690: (PreferenceChangeListener listener); 691: 692: public abstract void removeNodeChangeListener(NodeChangeListener listener); 693: 694: public abstract void removePreferenceChangeListener 695: (PreferenceChangeListener listener); 696: }