Source for java.lang.Class

   1: /* Class.java -- Representation of a Java class.
   2:    Copyright (C) 1998, 1999, 2000, 2002, 2003, 2004, 2005
   3:    Free Software Foundation
   4: 
   5: This file is part of GNU Classpath.
   6: 
   7: GNU Classpath is free software; you can redistribute it and/or modify
   8: it under the terms of the GNU General Public License as published by
   9: the Free Software Foundation; either version 2, or (at your option)
  10: any later version.
  11: 
  12: GNU Classpath is distributed in the hope that it will be useful, but
  13: WITHOUT ANY WARRANTY; without even the implied warranty of
  14: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15: General Public License for more details.
  16: 
  17: You should have received a copy of the GNU General Public License
  18: along with GNU Classpath; see the file COPYING.  If not, write to the
  19: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  20: 02110-1301 USA.
  21: 
  22: Linking this library statically or dynamically with other modules is
  23: making a combined work based on this library.  Thus, the terms and
  24: conditions of the GNU General Public License cover the whole
  25: combination.
  26: 
  27: As a special exception, the copyright holders of this library give you
  28: permission to link this library with independent modules to produce an
  29: executable, regardless of the license terms of these independent
  30: modules, and to copy and distribute the resulting executable under
  31: terms of your choice, provided that you also meet, for each linked
  32: independent module, the terms and conditions of the license of that
  33: module.  An independent module is a module which is not derived from
  34: or based on this library.  If you modify this library, you may extend
  35: this exception to your version of the library, but you are not
  36: obligated to do so.  If you do not wish to do so, delete this
  37: exception statement from your version. */
  38: 
  39: package java.lang;
  40: 
  41: import gnu.classpath.VMStackWalker;
  42: 
  43: import java.io.InputStream;
  44: import java.io.Serializable;
  45: import java.lang.reflect.Constructor;
  46: import java.lang.reflect.Field;
  47: import java.lang.reflect.InvocationTargetException;
  48: import java.lang.reflect.Member;
  49: import java.lang.reflect.Method;
  50: import java.lang.reflect.Modifier;
  51: import java.net.URL;
  52: import java.security.AccessController;
  53: import java.security.AllPermission;
  54: import java.security.Permissions;
  55: import java.security.PrivilegedAction;
  56: import java.security.ProtectionDomain;
  57: import java.util.ArrayList;
  58: import java.util.Arrays;
  59: import java.util.HashMap;
  60: import java.util.HashSet;
  61: 
  62: 
  63: /**
  64:  * A Class represents a Java type.  There will never be multiple Class
  65:  * objects with identical names and ClassLoaders. Primitive types, array
  66:  * types, and void also have a Class object.
  67:  *
  68:  * <p>Arrays with identical type and number of dimensions share the same class.
  69:  * The array class ClassLoader is the same as the ClassLoader of the element
  70:  * type of the array (which can be null to indicate the bootstrap classloader).
  71:  * The name of an array class is <code>[&lt;signature format&gt;;</code>.
  72:  * <p> For example,
  73:  * String[]'s class is <code>[Ljava.lang.String;</code>. boolean, byte,
  74:  * short, char, int, long, float and double have the "type name" of
  75:  * Z,B,S,C,I,J,F,D for the purposes of array classes.  If it's a
  76:  * multidimensioned array, the same principle applies:
  77:  * <code>int[][][]</code> == <code>[[[I</code>.
  78:  *
  79:  * <p>There is no public constructor - Class objects are obtained only through
  80:  * the virtual machine, as defined in ClassLoaders.
  81:  *
  82:  * @serialData Class objects serialize specially:
  83:  * <code>TC_CLASS ClassDescriptor</code>. For more serialization information,
  84:  * see {@link ObjectStreamClass}.
  85:  *
  86:  * @author John Keiser
  87:  * @author Eric Blake (ebb9@email.byu.edu)
  88:  * @author Tom Tromey (tromey@cygnus.com)
  89:  * @since 1.0
  90:  * @see ClassLoader
  91:  */
  92: public final class Class implements Serializable
  93: {
  94:   /**
  95:    * Compatible with JDK 1.0+.
  96:    */
  97:   private static final long serialVersionUID = 3206093459760846163L;
  98: 
  99:   /** The class signers. */
 100:   private Object[] signers = null;
 101:   /** The class protection domain. */
 102:   private final ProtectionDomain pd;
 103: 
 104:   /* We use an inner class, so that Class doesn't have a static initializer */
 105:   private static final class StaticData
 106:   {
 107:     static final ProtectionDomain unknownProtectionDomain;
 108: 
 109:     static
 110:     {
 111:       Permissions permissions = new Permissions();
 112:       permissions.add(new AllPermission());
 113:       unknownProtectionDomain = new ProtectionDomain(null, permissions);
 114:     }
 115:   }
 116: 
 117:   final transient Object vmdata;
 118: 
 119:   /** newInstance() caches the default constructor */
 120:   private transient Constructor constructor;
 121: 
 122:   /**
 123:    * Class is non-instantiable from Java code; only the VM can create
 124:    * instances of this class.
 125:    */
 126:   Class(Object vmdata)
 127:   {
 128:     this(vmdata, null);
 129:   }
 130: 
 131:   Class(Object vmdata, ProtectionDomain pd)
 132:   {
 133:     this.vmdata = vmdata;
 134:     // If the VM didn't supply a protection domain and the class is an array,
 135:     // we "inherit" the protection domain from the component type class. This
 136:     // saves the VM from having to worry about protection domains for array
 137:     // classes.
 138:     if (pd == null && isArray())
 139:       this.pd = getComponentType().pd;
 140:     else
 141:       this.pd = pd;
 142:   }
 143: 
 144:   /**
 145:    * Use the classloader of the current class to load, link, and initialize
 146:    * a class. This is equivalent to your code calling
 147:    * <code>Class.forName(name, true, getClass().getClassLoader())</code>.
 148:    *
 149:    * @param name the name of the class to find
 150:    * @return the Class object representing the class
 151:    * @throws ClassNotFoundException if the class was not found by the
 152:    *         classloader
 153:    * @throws LinkageError if linking the class fails
 154:    * @throws ExceptionInInitializerError if the class loads, but an exception
 155:    *         occurs during initialization
 156:    */
 157:   public static Class forName(String name) throws ClassNotFoundException
 158:   {
 159:     Class result = VMClass.forName (name);
 160:     if (result == null)
 161:       result = Class.forName(name, true,
 162:     VMStackWalker.getCallingClassLoader());
 163:     return result;
 164:   }
 165: 
 166:   /**
 167:    * Use the specified classloader to load and link a class. If the loader
 168:    * is null, this uses the bootstrap class loader (provide the security
 169:    * check succeeds). Unfortunately, this method cannot be used to obtain
 170:    * the Class objects for primitive types or for void, you have to use
 171:    * the fields in the appropriate java.lang wrapper classes.
 172:    *
 173:    * <p>Calls <code>classloader.loadclass(name, initialize)</code>.
 174:    *
 175:    * @param name the name of the class to find
 176:    * @param initialize whether or not to initialize the class at this time
 177:    * @param classloader the classloader to use to find the class; null means
 178:    *        to use the bootstrap class loader
 179:    *
 180:    * @return the class object for the given class
 181:    *
 182:    * @throws ClassNotFoundException if the class was not found by the
 183:    *         classloader
 184:    * @throws LinkageError if linking the class fails
 185:    * @throws ExceptionInInitializerError if the class loads, but an exception
 186:    *         occurs during initialization
 187:    * @throws SecurityException if the <code>classloader</code> argument
 188:    *         is <code>null</code> and the caller does not have the
 189:    *         <code>RuntimePermission("getClassLoader")</code> permission
 190:    * @see ClassLoader
 191:    * @since 1.2
 192:    */
 193:   public static Class forName(String name, boolean initialize,
 194:                               ClassLoader classloader)
 195:     throws ClassNotFoundException
 196:   {
 197:     if (classloader == null)
 198:       {
 199:         // Check if we may access the bootstrap classloader
 200:         SecurityManager sm = SecurityManager.current;
 201:         if (sm != null)
 202:           {
 203:             // Get the calling classloader
 204:             ClassLoader cl = VMStackWalker.getCallingClassLoader();
 205:             if (cl != null)
 206:               sm.checkPermission(new RuntimePermission("getClassLoader"));
 207:           }
 208:     if (name.startsWith("["))
 209:       return VMClass.loadArrayClass(name, null);
 210:     Class c = VMClassLoader.loadClass(name, true);
 211:     if (c != null)
 212:       {
 213:         if (initialize)
 214:           VMClass.initialize(c);
 215:         return c;
 216:       }
 217:         throw new ClassNotFoundException(name);
 218:       }
 219:     if (name.startsWith("["))
 220:       return VMClass.loadArrayClass(name, classloader);
 221:     Class c = classloader.loadClass(name);
 222:     classloader.resolveClass(c);
 223:     if (initialize)
 224:       VMClass.initialize(c);
 225:     return c;
 226:   }
 227:   
 228:   /**
 229:    * Get all the public member classes and interfaces declared in this
 230:    * class or inherited from superclasses. This returns an array of length
 231:    * 0 if there are no member classes, including for primitive types. A
 232:    * security check may be performed, with
 233:    * <code>checkMemberAccess(this, Member.PUBLIC)</code> as well as
 234:    * <code>checkPackageAccess</code> both having to succeed.
 235:    *
 236:    * @return all public member classes in this class
 237:    * @throws SecurityException if the security check fails
 238:    * @since 1.1
 239:    */
 240:   public Class[] getClasses()
 241:   {
 242:     memberAccessCheck(Member.PUBLIC);
 243:     return internalGetClasses();
 244:   }
 245: 
 246:   /**
 247:    * Like <code>getClasses()</code> but without the security checks.
 248:    */
 249:   private Class[] internalGetClasses()
 250:   {
 251:     ArrayList list = new ArrayList();
 252:     list.addAll(Arrays.asList(getDeclaredClasses(true)));
 253:     Class superClass = getSuperclass();
 254:     if (superClass != null)
 255:       list.addAll(Arrays.asList(superClass.internalGetClasses()));
 256:     return (Class[])list.toArray(new Class[list.size()]);
 257:   }
 258:   
 259:   /**
 260:    * Get the ClassLoader that loaded this class.  If the class was loaded
 261:    * by the bootstrap classloader, this method will return null.
 262:    * If there is a security manager, and the caller's class loader is not
 263:    * an ancestor of the requested one, a security check of
 264:    * <code>RuntimePermission("getClassLoader")</code>
 265:    * must first succeed. Primitive types and void return null.
 266:    *
 267:    * @return the ClassLoader that loaded this class
 268:    * @throws SecurityException if the security check fails
 269:    * @see ClassLoader
 270:    * @see RuntimePermission
 271:    */
 272:   public ClassLoader getClassLoader()
 273:   {
 274:     if (isPrimitive())
 275:       return null;
 276: 
 277:     ClassLoader loader = VMClass.getClassLoader(this);
 278:     // Check if we may get the classloader
 279:     SecurityManager sm = SecurityManager.current;
 280:     if (sm != null)
 281:       {
 282:         // Get the calling classloader
 283:     ClassLoader cl = VMStackWalker.getCallingClassLoader();
 284:         if (cl != null && !cl.isAncestorOf(loader))
 285:           sm.checkPermission(new RuntimePermission("getClassLoader"));
 286:       }
 287:     return loader;
 288:   }
 289: 
 290:   /**
 291:    * If this is an array, get the Class representing the type of array.
 292:    * Examples: "[[Ljava.lang.String;" would return "[Ljava.lang.String;", and
 293:    * calling getComponentType on that would give "java.lang.String".  If
 294:    * this is not an array, returns null.
 295:    *
 296:    * @return the array type of this class, or null
 297:    * @see Array
 298:    * @since 1.1
 299:    */
 300:   public Class getComponentType()
 301:   {
 302:     return VMClass.getComponentType (this);
 303:   }
 304: 
 305:   /**
 306:    * Get a public constructor declared in this class. If the constructor takes
 307:    * no argument, an array of zero elements and null are equivalent for the
 308:    * types argument. A security check may be performed, with
 309:    * <code>checkMemberAccess(this, Member.PUBLIC)</code> as well as
 310:    * <code>checkPackageAccess</code> both having to succeed.
 311:    *
 312:    * @param types the type of each parameter
 313:    * @return the constructor
 314:    * @throws NoSuchMethodException if the constructor does not exist
 315:    * @throws SecurityException if the security check fails
 316:    * @see #getConstructors()
 317:    * @since 1.1
 318:    */
 319:   public Constructor getConstructor(Class[] types) throws NoSuchMethodException
 320:   {
 321:     memberAccessCheck(Member.PUBLIC);
 322:     Constructor[] constructors = getDeclaredConstructors(true);
 323:     for (int i = 0; i < constructors.length; i++)
 324:       {
 325:     Constructor constructor = constructors[i];
 326:     if (matchParameters(types, constructor.getParameterTypes()))
 327:       return constructor;
 328:       }
 329:     throw new NoSuchMethodException();
 330:   }
 331: 
 332:   /**
 333:    * Get all the public constructors of this class. This returns an array of
 334:    * length 0 if there are no constructors, including for primitive types,
 335:    * arrays, and interfaces. It does, however, include the default
 336:    * constructor if one was supplied by the compiler. A security check may
 337:    * be performed, with <code>checkMemberAccess(this, Member.PUBLIC)</code>
 338:    * as well as <code>checkPackageAccess</code> both having to succeed.
 339:    *
 340:    * @return all public constructors in this class
 341:    * @throws SecurityException if the security check fails
 342:    * @since 1.1
 343:    */
 344:   public Constructor[] getConstructors()
 345:   {
 346:     memberAccessCheck(Member.PUBLIC);
 347:     return getDeclaredConstructors(true);
 348:   }
 349: 
 350:   /**
 351:    * Get a constructor declared in this class. If the constructor takes no
 352:    * argument, an array of zero elements and null are equivalent for the
 353:    * types argument. A security check may be performed, with
 354:    * <code>checkMemberAccess(this, Member.DECLARED)</code> as well as
 355:    * <code>checkPackageAccess</code> both having to succeed.
 356:    *
 357:    * @param types the type of each parameter
 358:    * @return the constructor
 359:    * @throws NoSuchMethodException if the constructor does not exist
 360:    * @throws SecurityException if the security check fails
 361:    * @see #getDeclaredConstructors()
 362:    * @since 1.1
 363:    */
 364:   public Constructor getDeclaredConstructor(Class[] types)
 365:     throws NoSuchMethodException
 366:   {
 367:     memberAccessCheck(Member.DECLARED);
 368:     Constructor[] constructors = getDeclaredConstructors(false);
 369:     for (int i = 0; i < constructors.length; i++)
 370:       {
 371:     Constructor constructor = constructors[i];
 372:     if (matchParameters(types, constructor.getParameterTypes()))
 373:       return constructor;
 374:       }
 375:     throw new NoSuchMethodException();
 376:   }
 377: 
 378:   /**
 379:    * Get all the declared member classes and interfaces in this class, but
 380:    * not those inherited from superclasses. This returns an array of length
 381:    * 0 if there are no member classes, including for primitive types. A
 382:    * security check may be performed, with
 383:    * <code>checkMemberAccess(this, Member.DECLARED)</code> as well as
 384:    * <code>checkPackageAccess</code> both having to succeed.
 385:    *
 386:    * @return all declared member classes in this class
 387:    * @throws SecurityException if the security check fails
 388:    * @since 1.1
 389:    */
 390:   public Class[] getDeclaredClasses()
 391:   {
 392:     memberAccessCheck(Member.DECLARED);
 393:     return getDeclaredClasses(false);
 394:   }
 395: 
 396:   Class[] getDeclaredClasses (boolean publicOnly)
 397:   {
 398:     return VMClass.getDeclaredClasses (this, publicOnly);
 399:   }
 400: 
 401:   /**
 402:    * Get all the declared constructors of this class. This returns an array of
 403:    * length 0 if there are no constructors, including for primitive types,
 404:    * arrays, and interfaces. It does, however, include the default
 405:    * constructor if one was supplied by the compiler. A security check may
 406:    * be performed, with <code>checkMemberAccess(this, Member.DECLARED)</code>
 407:    * as well as <code>checkPackageAccess</code> both having to succeed.
 408:    *
 409:    * @return all constructors in this class
 410:    * @throws SecurityException if the security check fails
 411:    * @since 1.1
 412:    */
 413:   public Constructor[] getDeclaredConstructors()
 414:   {
 415:     memberAccessCheck(Member.DECLARED);
 416:     return getDeclaredConstructors(false);
 417:   }
 418: 
 419:   Constructor[] getDeclaredConstructors (boolean publicOnly)
 420:   {
 421:     return VMClass.getDeclaredConstructors (this, publicOnly);
 422:   }
 423:   
 424:   /**
 425:    * Get a field declared in this class, where name is its simple name. The
 426:    * implicit length field of arrays is not available. A security check may
 427:    * be performed, with <code>checkMemberAccess(this, Member.DECLARED)</code>
 428:    * as well as <code>checkPackageAccess</code> both having to succeed.
 429:    *
 430:    * @param name the name of the field
 431:    * @return the field
 432:    * @throws NoSuchFieldException if the field does not exist
 433:    * @throws SecurityException if the security check fails
 434:    * @see #getDeclaredFields()
 435:    * @since 1.1
 436:    */
 437:   public Field getDeclaredField(String name) throws NoSuchFieldException
 438:   {
 439:     memberAccessCheck(Member.DECLARED);
 440:     Field[] fields = getDeclaredFields(false);
 441:     for (int i = 0; i < fields.length; i++)
 442:       {
 443:     if (fields[i].getName().equals(name))
 444:       return fields[i];
 445:       }
 446:     throw new NoSuchFieldException();
 447:   }
 448: 
 449:   /**
 450:    * Get all the declared fields in this class, but not those inherited from
 451:    * superclasses. This returns an array of length 0 if there are no fields,
 452:    * including for primitive types. This does not return the implicit length
 453:    * field of arrays. A security check may be performed, with
 454:    * <code>checkMemberAccess(this, Member.DECLARED)</code> as well as
 455:    * <code>checkPackageAccess</code> both having to succeed.
 456:    *
 457:    * @return all declared fields in this class
 458:    * @throws SecurityException if the security check fails
 459:    * @since 1.1
 460:    */
 461:   public Field[] getDeclaredFields()
 462:   {
 463:     memberAccessCheck(Member.DECLARED);
 464:     return getDeclaredFields(false);
 465:   }
 466: 
 467:   Field[] getDeclaredFields (boolean publicOnly)
 468:   {
 469:     return VMClass.getDeclaredFields (this, publicOnly);
 470:   }
 471: 
 472:   /**
 473:    * Get a method declared in this class, where name is its simple name. The
 474:    * implicit methods of Object are not available from arrays or interfaces.
 475:    * Constructors (named "&lt;init&gt;" in the class file) and class initializers
 476:    * (name "&lt;clinit&gt;") are not available.  The Virtual Machine allows
 477:    * multiple methods with the same signature but differing return types; in
 478:    * such a case the most specific return types are favored, then the final
 479:    * choice is arbitrary. If the method takes no argument, an array of zero
 480:    * elements and null are equivalent for the types argument. A security
 481:    * check may be performed, with
 482:    * <code>checkMemberAccess(this, Member.DECLARED)</code> as well as
 483:    * <code>checkPackageAccess</code> both having to succeed.
 484:    *
 485:    * @param methodName the name of the method
 486:    * @param types the type of each parameter
 487:    * @return the method
 488:    * @throws NoSuchMethodException if the method does not exist
 489:    * @throws SecurityException if the security check fails
 490:    * @see #getDeclaredMethods()
 491:    * @since 1.1
 492:    */
 493:   public Method getDeclaredMethod(String methodName, Class[] types)
 494:     throws NoSuchMethodException
 495:   {
 496:     memberAccessCheck(Member.DECLARED);
 497:     Method match = matchMethod(getDeclaredMethods(false), methodName, types);
 498:     if (match == null)
 499:       throw new NoSuchMethodException(methodName);
 500:     return match;
 501:   }
 502: 
 503:   /**
 504:    * Get all the declared methods in this class, but not those inherited from
 505:    * superclasses. This returns an array of length 0 if there are no methods,
 506:    * including for primitive types. This does include the implicit methods of
 507:    * arrays and interfaces which mirror methods of Object, nor does it
 508:    * include constructors or the class initialization methods. The Virtual
 509:    * Machine allows multiple methods with the same signature but differing
 510:    * return types; all such methods are in the returned array. A security
 511:    * check may be performed, with
 512:    * <code>checkMemberAccess(this, Member.DECLARED)</code> as well as
 513:    * <code>checkPackageAccess</code> both having to succeed.
 514:    *
 515:    * @return all declared methods in this class
 516:    * @throws SecurityException if the security check fails
 517:    * @since 1.1
 518:    */
 519:   public Method[] getDeclaredMethods()
 520:   {
 521:     memberAccessCheck(Member.DECLARED);
 522:     return getDeclaredMethods(false);
 523:   }
 524: 
 525:   Method[] getDeclaredMethods (boolean publicOnly)
 526:   {
 527:     return VMClass.getDeclaredMethods (this, publicOnly);
 528:   }
 529:  
 530:   /**
 531:    * If this is a nested or inner class, return the class that declared it.
 532:    * If not, return null.
 533:    *
 534:    * @return the declaring class of this class
 535:    * @since 1.1
 536:    */
 537:   public Class getDeclaringClass()
 538:   {
 539:     return VMClass.getDeclaringClass (this);
 540:   }
 541: 
 542:   /**
 543:    * Get a public field declared or inherited in this class, where name is
 544:    * its simple name. If the class contains multiple accessible fields by
 545:    * that name, an arbitrary one is returned. The implicit length field of
 546:    * arrays is not available. A security check may be performed, with
 547:    * <code>checkMemberAccess(this, Member.PUBLIC)</code> as well as
 548:    * <code>checkPackageAccess</code> both having to succeed.
 549:    *
 550:    * @param fieldName the name of the field
 551:    * @return the field
 552:    * @throws NoSuchFieldException if the field does not exist
 553:    * @throws SecurityException if the security check fails
 554:    * @see #getFields()
 555:    * @since 1.1
 556:    */
 557:   public Field getField(String fieldName)
 558:     throws NoSuchFieldException
 559:   {
 560:     memberAccessCheck(Member.PUBLIC);
 561:     Field field = internalGetField(fieldName);
 562:     if (field == null)
 563:       throw new NoSuchFieldException(fieldName);
 564:     return field;
 565:   }
 566: 
 567:   /**
 568:    * Get all the public fields declared in this class or inherited from
 569:    * superclasses. This returns an array of length 0 if there are no fields,
 570:    * including for primitive types. This does not return the implicit length
 571:    * field of arrays. A security check may be performed, with
 572:    * <code>checkMemberAccess(this, Member.PUBLIC)</code> as well as
 573:    * <code>checkPackageAccess</code> both having to succeed.
 574:    *
 575:    * @return all public fields in this class
 576:    * @throws SecurityException if the security check fails
 577:    * @since 1.1
 578:    */
 579:   public Field[] getFields()
 580:   {
 581:     memberAccessCheck(Member.PUBLIC);
 582:     return internalGetFields();
 583:   }
 584: 
 585:   /**
 586:    * Like <code>getFields()</code> but without the security checks.
 587:    */
 588:   private Field[] internalGetFields()
 589:   {
 590:     HashSet set = new HashSet();
 591:     set.addAll(Arrays.asList(getDeclaredFields(true)));
 592:     Class[] interfaces = getInterfaces();
 593:     for (int i = 0; i < interfaces.length; i++)
 594:       set.addAll(Arrays.asList(interfaces[i].internalGetFields()));
 595:     Class superClass = getSuperclass();
 596:     if (superClass != null)
 597:       set.addAll(Arrays.asList(superClass.internalGetFields()));
 598:     return (Field[])set.toArray(new Field[set.size()]);
 599:   }
 600: 
 601:   /**
 602:    * Returns the <code>Package</code> in which this class is defined
 603:    * Returns null when this information is not available from the
 604:    * classloader of this class or when the classloader of this class
 605:    * is null.
 606:    *
 607:    * @return the package for this class, if it is available
 608:    * @since 1.2
 609:    */
 610:   public Package getPackage()
 611:   {
 612:     ClassLoader cl = getClassLoader();
 613:     if (cl != null)
 614:       return cl.getPackage(getPackagePortion(getName()));
 615:     return null;
 616:   }
 617: 
 618:   /**
 619:    * Get the interfaces this class <em>directly</em> implements, in the
 620:    * order that they were declared. This returns an empty array, not null,
 621:    * for Object, primitives, void, and classes or interfaces with no direct
 622:    * superinterface. Array types return Cloneable and Serializable.
 623:    *
 624:    * @return the interfaces this class directly implements
 625:    */
 626:   public Class[] getInterfaces()
 627:   {
 628:     return VMClass.getInterfaces (this);
 629:   }
 630: 
 631:   private static final class MethodKey
 632:   {
 633:     private String name;
 634:     private Class[] params;
 635:     private Class returnType;
 636:     private int hash;
 637:     
 638:     MethodKey(Method m)
 639:     {
 640:       name = m.getName();
 641:       params = m.getParameterTypes();
 642:       returnType = m.getReturnType();
 643:       hash = name.hashCode() ^ returnType.hashCode();
 644:       for(int i = 0; i < params.length; i++)
 645:     {
 646:       hash ^= params[i].hashCode();
 647:     }
 648:     }
 649:     
 650:     public boolean equals(Object o)
 651:     {
 652:       if(o instanceof MethodKey)
 653:     {
 654:       MethodKey m = (MethodKey)o;
 655:       if(m.name.equals(name) && m.params.length == params.length && m.returnType == returnType)
 656:         {
 657:           for(int i = 0; i < params.length; i++)
 658:         {
 659:           if(m.params[i] != params[i])
 660:             {
 661:               return false;
 662:             }
 663:         }
 664:           return true;
 665:         }
 666:     }
 667:       return false;
 668:     }
 669:     
 670:     public int hashCode()
 671:     {
 672:       return hash;
 673:     }
 674:   }
 675:   
 676:   /**
 677:    * Get a public method declared or inherited in this class, where name is
 678:    * its simple name. The implicit methods of Object are not available from
 679:    * interfaces.  Constructors (named "&lt;init&gt;" in the class file) and class
 680:    * initializers (name "&lt;clinit&gt;") are not available.  The Virtual
 681:    * Machine allows multiple methods with the same signature but differing
 682:    * return types, and the class can inherit multiple methods of the same
 683:    * return type; in such a case the most specific return types are favored,
 684:    * then the final choice is arbitrary. If the method takes no argument, an
 685:    * array of zero elements and null are equivalent for the types argument.
 686:    * A security check may be performed, with
 687:    * <code>checkMemberAccess(this, Member.PUBLIC)</code> as well as
 688:    * <code>checkPackageAccess</code> both having to succeed.
 689:    *
 690:    * @param methodName the name of the method
 691:    * @param types the type of each parameter
 692:    * @return the method
 693:    * @throws NoSuchMethodException if the method does not exist
 694:    * @throws SecurityException if the security check fails
 695:    * @see #getMethods()
 696:    * @since 1.1
 697:    */
 698:   public Method getMethod(String methodName, Class[] types)
 699:     throws NoSuchMethodException
 700:   {
 701:     memberAccessCheck(Member.PUBLIC);
 702:     Method method = internalGetMethod(methodName, types);
 703:     if (method == null)
 704:       throw new NoSuchMethodException(methodName);
 705:     return method;
 706:   }
 707: 
 708:   /**
 709:    * Like <code>getMethod(String,Class[])</code> but without the security
 710:    * checks and returns null instead of throwing NoSuchMethodException.
 711:    */
 712:   private Method internalGetMethod(String methodName, Class[] args)
 713:   {
 714:     Method match = matchMethod(getDeclaredMethods(true), methodName, args);
 715:     if (match != null)
 716:       return match;
 717:     Class superClass = getSuperclass();
 718:     if (superClass != null)
 719:       {
 720:     match = superClass.internalGetMethod(methodName, args);
 721:     if(match != null)
 722:       return match;
 723:       }
 724:     Class[] interfaces = getInterfaces();
 725:     for (int i = 0; i < interfaces.length; i++)
 726:       {
 727:     match = interfaces[i].internalGetMethod(methodName, args);
 728:     if (match != null)
 729:       return match;
 730:       }
 731:     return null;
 732:   }
 733: 
 734:   /** 
 735:    * Find the best matching method in <code>list</code> according to
 736:    * the definition of ``best matching'' used by <code>getMethod()</code>
 737:    *
 738:    * <p>
 739:    * Returns the method if any, otherwise <code>null</code>.
 740:    *
 741:    * @param list List of methods to search
 742:    * @param name Name of method
 743:    * @param args Method parameter types
 744:    * @see #getMethod()
 745:    */
 746:   private static Method matchMethod(Method[] list, String name, Class[] args)
 747:   {
 748:     Method match = null;
 749:     for (int i = 0; i < list.length; i++)
 750:       {
 751:     Method method = list[i];
 752:     if (!method.getName().equals(name))
 753:       continue;
 754:     if (!matchParameters(args, method.getParameterTypes()))
 755:       continue;
 756:     if (match == null
 757:         || match.getReturnType().isAssignableFrom(method.getReturnType()))
 758:       match = method;
 759:       }
 760:     return match;
 761:   }
 762: 
 763:   /**
 764:    * Check for an exact match between parameter type lists.
 765:    * Either list may be <code>null</code> to mean a list of
 766:    * length zero.
 767:    */
 768:   private static boolean matchParameters(Class[] types1, Class[] types2)
 769:   {
 770:     if (types1 == null)
 771:       return types2 == null || types2.length == 0;
 772:     if (types2 == null)
 773:       return types1 == null || types1.length == 0;
 774:     if (types1.length != types2.length)
 775:       return false;
 776:     for (int i = 0; i < types1.length; i++)
 777:       {
 778:     if (types1[i] != types2[i])
 779:       return false;
 780:       }
 781:     return true;
 782:   }
 783:   
 784:   /**
 785:    * Get all the public methods declared in this class or inherited from
 786:    * superclasses. This returns an array of length 0 if there are no methods,
 787:    * including for primitive types. This does not include the implicit
 788:    * methods of interfaces which mirror methods of Object, nor does it
 789:    * include constructors or the class initialization methods. The Virtual
 790:    * Machine allows multiple methods with the same signature but differing
 791:    * return types; all such methods are in the returned array. A security
 792:    * check may be performed, with
 793:    * <code>checkMemberAccess(this, Member.PUBLIC)</code> as well as
 794:    * <code>checkPackageAccess</code> both having to succeed.
 795:    *
 796:    * @return all public methods in this class
 797:    * @throws SecurityException if the security check fails
 798:    * @since 1.1
 799:    */
 800:   public Method[] getMethods()
 801:   {
 802:     memberAccessCheck(Member.PUBLIC);
 803:     // NOTE the API docs claim that no methods are returned for arrays,
 804:     // but Sun's implementation *does* return the public methods of Object
 805:     // (as would be expected), so we follow their implementation instead
 806:     // of their documentation.
 807:     return internalGetMethods();
 808:   }
 809: 
 810:   /**
 811:    * Like <code>getMethods()</code> but without the security checks.
 812:    */
 813:   private Method[] internalGetMethods()
 814:   {
 815:     HashMap map = new HashMap();
 816:     Method[] methods;
 817:     Class[] interfaces = getInterfaces();
 818:     for(int i = 0; i < interfaces.length; i++)
 819:       {
 820:     methods = interfaces[i].internalGetMethods();
 821:     for(int j = 0; j < methods.length; j++)
 822:       {
 823:         map.put(new MethodKey(methods[j]), methods[j]);
 824:       }
 825:       }
 826:     Class superClass = getSuperclass();
 827:     if(superClass != null)
 828:       {
 829:     methods = superClass.internalGetMethods();
 830:     for(int i = 0; i < methods.length; i++)
 831:       {
 832:         map.put(new MethodKey(methods[i]), methods[i]);
 833:       }
 834:       }
 835:     methods = getDeclaredMethods(true);
 836:     for(int i = 0; i < methods.length; i++)
 837:       {
 838:     map.put(new MethodKey(methods[i]), methods[i]);
 839:       }
 840:     return (Method[])map.values().toArray(new Method[map.size()]);
 841:   }
 842: 
 843:   /**
 844:    * Get the modifiers of this class.  These can be decoded using Modifier,
 845:    * and is limited to one of public, protected, or private, and any of
 846:    * final, static, abstract, or interface. An array class has the same
 847:    * public, protected, or private modifier as its component type, and is
 848:    * marked final but not an interface. Primitive types and void are marked
 849:    * public and final, but not an interface.
 850:    *
 851:    * @return the modifiers of this class
 852:    * @see Modifer
 853:    * @since 1.1
 854:    */
 855:   public int getModifiers()
 856:   {
 857:     return VMClass.getModifiers (this, false);
 858:   }
 859:   
 860:   /**
 861:    * Get the name of this class, separated by dots for package separators.
 862:    * If the class represents a primitive type, or void, then the
 863:    * name of the type as it appears in the Java programming language
 864:    * is returned.  For instance, <code>Byte.TYPE.getName()</code>
 865:    * returns "byte".
 866:    *
 867:    * Arrays are specially encoded as shown on this table.
 868:    * <pre>
 869:    * array type          [<em>element type</em>
 870:    *                     (note that the element type is encoded per
 871:    *                      this table)
 872:    * boolean             Z
 873:    * byte                B
 874:    * char                C
 875:    * short               S
 876:    * int                 I
 877:    * long                J
 878:    * float               F
 879:    * double              D
 880:    * void                V
 881:    * class or interface, alone: &lt;dotted name&gt;
 882:    * class or interface, as element type: L&lt;dotted name&gt;;
 883:    * </pre>
 884:    *
 885:    * @return the name of this class
 886:    */
 887:   public String getName()
 888:   { 
 889:     return VMClass.getName (this);
 890:   }
 891: 
 892:   /**
 893:    * Get a resource URL using this class's package using the
 894:    * getClassLoader().getResource() method.  If this class was loaded using
 895:    * the system classloader, ClassLoader.getSystemResource() is used instead.
 896:    *
 897:    * <p>If the name you supply is absolute (it starts with a <code>/</code>),
 898:    * then the leading <code>/</code> is removed and it is passed on to
 899:    * getResource(). If it is relative, the package name is prepended, and
 900:    * <code>.</code>'s are replaced with <code>/</code>.
 901:    *
 902:    * <p>The URL returned is system- and classloader-dependent, and could
 903:    * change across implementations.
 904:    *
 905:    * @param resourceName the name of the resource, generally a path
 906:    * @return the URL to the resource
 907:    * @throws NullPointerException if name is null
 908:    * @since 1.1
 909:    */
 910:   public URL getResource(String resourceName)
 911:   {
 912:     String name = resourcePath(resourceName);
 913:     ClassLoader loader = getClassLoader();
 914:     if (loader == null)
 915:       return ClassLoader.getSystemResource(name);
 916:     return loader.getResource(name);
 917:   }
 918: 
 919:   /**
 920:    * Get a resource using this class's package using the
 921:    * getClassLoader().getResourceAsStream() method.  If this class was loaded
 922:    * using the system classloader, ClassLoader.getSystemResource() is used
 923:    * instead.
 924:    *
 925:    * <p>If the name you supply is absolute (it starts with a <code>/</code>),
 926:    * then the leading <code>/</code> is removed and it is passed on to
 927:    * getResource(). If it is relative, the package name is prepended, and
 928:    * <code>.</code>'s are replaced with <code>/</code>.
 929:    *
 930:    * <p>The URL returned is system- and classloader-dependent, and could
 931:    * change across implementations.
 932:    *
 933:    * @param resourceName the name of the resource, generally a path
 934:    * @return an InputStream with the contents of the resource in it, or null
 935:    * @throws NullPointerException if name is null
 936:    * @since 1.1
 937:    */
 938:   public InputStream getResourceAsStream(String resourceName)
 939:   {
 940:     String name = resourcePath(resourceName);
 941:     ClassLoader loader = getClassLoader();
 942:     if (loader == null)
 943:       return ClassLoader.getSystemResourceAsStream(name);
 944:     return loader.getResourceAsStream(name);
 945:   }
 946: 
 947:   private String resourcePath(String resourceName)
 948:   {
 949:     if (resourceName.length() > 0)
 950:       {
 951:     if (resourceName.charAt(0) != '/')
 952:       {
 953:         String pkg = getPackagePortion(getName());
 954:         if (pkg.length() > 0)
 955:           resourceName = pkg.replace('.','/') + '/' + resourceName;
 956:       }
 957:     else
 958:       {
 959:         resourceName = resourceName.substring(1);
 960:       }
 961:       }
 962:     return resourceName;
 963:   }
 964: 
 965:   /**
 966:    * Get the signers of this class. This returns null if there are no signers,
 967:    * such as for primitive types or void.
 968:    *
 969:    * @return the signers of this class
 970:    * @since 1.1
 971:    */
 972:   public Object[] getSigners()
 973:   {
 974:     return signers == null ? null : (Object[]) signers.clone ();
 975:   }
 976:   
 977:   /**
 978:    * Set the signers of this class.
 979:    *
 980:    * @param signers the signers of this class
 981:    */
 982:   void setSigners(Object[] signers)
 983:   {
 984:     this.signers = signers;
 985:   }
 986: 
 987:   /**
 988:    * Get the direct superclass of this class.  If this is an interface,
 989:    * Object, a primitive type, or void, it will return null. If this is an
 990:    * array type, it will return Object.
 991:    *
 992:    * @return the direct superclass of this class
 993:    */
 994:   public Class getSuperclass()
 995:   {
 996:     return VMClass.getSuperclass (this);
 997:   }
 998:   
 999:   /**
1000:    * Return whether this class is an array type.
1001:    *
1002:    * @return whether this class is an array type
1003:    * @since 1.1
1004:    */
1005:   public boolean isArray()
1006:   {
1007:     return VMClass.isArray (this);
1008:   }
1009:   
1010:   /**
1011:    * Discover whether an instance of the Class parameter would be an
1012:    * instance of this Class as well.  Think of doing
1013:    * <code>isInstance(c.newInstance())</code> or even
1014:    * <code>c.newInstance() instanceof (this class)</code>. While this
1015:    * checks widening conversions for objects, it must be exact for primitive
1016:    * types.
1017:    *
1018:    * @param c the class to check
1019:    * @return whether an instance of c would be an instance of this class
1020:    *         as well
1021:    * @throws NullPointerException if c is null
1022:    * @since 1.1
1023:    */
1024:   public boolean isAssignableFrom(Class c)
1025:   {
1026:     return VMClass.isAssignableFrom (this, c);
1027:   }
1028:  
1029:   /**
1030:    * Discover whether an Object is an instance of this Class.  Think of it
1031:    * as almost like <code>o instanceof (this class)</code>.
1032:    *
1033:    * @param o the Object to check
1034:    * @return whether o is an instance of this class
1035:    * @since 1.1
1036:    */
1037:   public boolean isInstance(Object o)
1038:   {
1039:     return VMClass.isInstance (this, o);
1040:   }
1041:   
1042:   /**
1043:    * Check whether this class is an interface or not.  Array types are not
1044:    * interfaces.
1045:    *
1046:    * @return whether this class is an interface or not
1047:    */
1048:   public boolean isInterface()
1049:   {
1050:     return VMClass.isInterface (this);
1051:   }
1052:   
1053:   /**
1054:    * Return whether this class is a primitive type.  A primitive type class
1055:    * is a class representing a kind of "placeholder" for the various
1056:    * primitive types, or void.  You can access the various primitive type
1057:    * classes through java.lang.Boolean.TYPE, java.lang.Integer.TYPE, etc.,
1058:    * or through boolean.class, int.class, etc.
1059:    *
1060:    * @return whether this class is a primitive type
1061:    * @see Boolean#TYPE
1062:    * @see Byte#TYPE
1063:    * @see Character#TYPE
1064:    * @see Short#TYPE
1065:    * @see Integer#TYPE
1066:    * @see Long#TYPE
1067:    * @see Float#TYPE
1068:    * @see Double#TYPE
1069:    * @see Void#TYPE
1070:    * @since 1.1
1071:    */
1072:   public boolean isPrimitive()
1073:   {
1074:     return VMClass.isPrimitive (this);
1075:   }
1076:   
1077:   /**
1078:    * Get a new instance of this class by calling the no-argument constructor.
1079:    * The class is initialized if it has not been already. A security check
1080:    * may be performed, with <code>checkMemberAccess(this, Member.PUBLIC)</code>
1081:    * as well as <code>checkPackageAccess</code> both having to succeed.
1082:    *
1083:    * @return a new instance of this class
1084:    * @throws InstantiationException if there is not a no-arg constructor
1085:    *         for this class, including interfaces, abstract classes, arrays,
1086:    *         primitive types, and void; or if an exception occurred during
1087:    *         the constructor
1088:    * @throws IllegalAccessException if you are not allowed to access the
1089:    *         no-arg constructor because of scoping reasons
1090:    * @throws SecurityException if the security check fails
1091:    * @throws ExceptionInInitializerError if class initialization caused by
1092:    *         this call fails with an exception
1093:    */
1094:   public Object newInstance()
1095:     throws InstantiationException, IllegalAccessException
1096:   {
1097:     memberAccessCheck(Member.PUBLIC);
1098:     Constructor constructor;
1099:     synchronized(this)
1100:       {
1101:     constructor = this.constructor;
1102:       }
1103:     if (constructor == null)
1104:       {
1105:     Constructor[] constructors = getDeclaredConstructors(false);
1106:     for (int i = 0; i < constructors.length; i++)
1107:       {
1108:         if (constructors[i].getParameterTypes().length == 0)
1109:           {
1110:         constructor = constructors[i];
1111:         break;
1112:           }
1113:       }
1114:     if (constructor == null)
1115:       throw new InstantiationException(getName());
1116:     if (!Modifier.isPublic(constructor.getModifiers())
1117:             || !Modifier.isPublic(VMClass.getModifiers(this, true)))
1118:       {
1119:         final Constructor finalConstructor = constructor;
1120:         AccessController.doPrivileged(new PrivilegedAction()
1121:           {
1122:         public Object run()
1123:             {
1124:           finalConstructor.setAccessible(true);
1125:           return null;
1126:         }
1127:           });
1128:       }
1129:     synchronized(this)
1130:       {
1131:         if (this.constructor == null)
1132:           this.constructor = constructor;
1133:       }        
1134:       }
1135:     int modifiers = constructor.getModifiers();
1136:     if (!Modifier.isPublic(modifiers)
1137:         || !Modifier.isPublic(VMClass.getModifiers(this, true)))
1138:       {
1139:     Class caller = VMStackWalker.getCallingClass();
1140:     if (caller != null &&
1141:         caller != this &&
1142:         (Modifier.isPrivate(modifiers)
1143:          || getClassLoader() != caller.getClassLoader()
1144:          || !getPackagePortion(getName())
1145:          .equals(getPackagePortion(caller.getName()))))
1146:       throw new IllegalAccessException(getName()
1147:                        + " has an inaccessible constructor");
1148:       }
1149:     try
1150:       {
1151:         return constructor.newInstance(null);
1152:       }
1153:     catch (InvocationTargetException e)
1154:       {
1155:     VMClass.throwException(e.getTargetException());
1156:     throw (InternalError) new InternalError
1157:       ("VMClass.throwException returned").initCause(e);
1158:       }
1159:   }
1160: 
1161:   /**
1162:    * Returns the protection domain of this class. If the classloader did not
1163:    * record the protection domain when creating this class the unknown
1164:    * protection domain is returned which has a <code>null</code> code source
1165:    * and all permissions. A security check may be performed, with
1166:    * <code>RuntimePermission("getProtectionDomain")</code>.
1167:    *
1168:    * @return the protection domain
1169:    * @throws SecurityException if the security manager exists and the caller
1170:    * does not have <code>RuntimePermission("getProtectionDomain")</code>.
1171:    * @see RuntimePermission
1172:    * @since 1.2
1173:    */
1174:   public ProtectionDomain getProtectionDomain()
1175:   {
1176:     SecurityManager sm = SecurityManager.current;
1177:     if (sm != null)
1178:       sm.checkPermission(new RuntimePermission("getProtectionDomain"));
1179: 
1180:     return pd == null ? StaticData.unknownProtectionDomain : pd;
1181:   }
1182: 
1183:   /**
1184:    * Return the human-readable form of this Object.  For an object, this
1185:    * is either "interface " or "class " followed by <code>getName()</code>,
1186:    * for primitive types and void it is just <code>getName()</code>.
1187:    *
1188:    * @return the human-readable form of this Object
1189:    */
1190:   public String toString()
1191:   {
1192:     if (isPrimitive())
1193:       return getName();
1194:     return (isInterface() ? "interface " : "class ") + getName();
1195:   }
1196: 
1197:   /**
1198:    * Returns the desired assertion status of this class, if it were to be
1199:    * initialized at this moment. The class assertion status, if set, is
1200:    * returned; the backup is the default package status; then if there is
1201:    * a class loader, that default is returned; and finally the system default
1202:    * is returned. This method seldom needs calling in user code, but exists
1203:    * for compilers to implement the assert statement. Note that there is no
1204:    * guarantee that the result of this method matches the class's actual
1205:    * assertion status.
1206:    *
1207:    * @return the desired assertion status
1208:    * @see ClassLoader#setClassAssertionStatus(String, boolean)
1209:    * @see ClassLoader#setPackageAssertionStatus(String, boolean)
1210:    * @see ClassLoader#setDefaultAssertionStatus(boolean)
1211:    * @since 1.4
1212:    */
1213:   public boolean desiredAssertionStatus()
1214:   {
1215:     ClassLoader c = getClassLoader();
1216:     Object status;
1217:     if (c == null)
1218:       return VMClassLoader.defaultAssertionStatus();
1219:     if (c.classAssertionStatus != null)
1220:       synchronized (c)
1221:         {
1222:           status = c.classAssertionStatus.get(getName());
1223:           if (status != null)
1224:             return status.equals(Boolean.TRUE);
1225:         }
1226:     else
1227:       {
1228:         status = ClassLoader.StaticData.
1229:                     systemClassAssertionStatus.get(getName());
1230:         if (status != null)
1231:           return status.equals(Boolean.TRUE);
1232:       }
1233:     if (c.packageAssertionStatus != null)
1234:       synchronized (c)
1235:         {
1236:           String name = getPackagePortion(getName());
1237:           if ("".equals(name))
1238:             status = c.packageAssertionStatus.get(null);
1239:           else
1240:             do
1241:               {
1242:                 status = c.packageAssertionStatus.get(name);
1243:                 name = getPackagePortion(name);
1244:               }
1245:             while (! "".equals(name) && status == null);
1246:           if (status != null)
1247:             return status.equals(Boolean.TRUE);
1248:         }
1249:     else
1250:       {
1251:         String name = getPackagePortion(getName());
1252:         if ("".equals(name))
1253:           status = ClassLoader.StaticData.
1254:                     systemPackageAssertionStatus.get(null);
1255:         else
1256:           do
1257:             {
1258:               status = ClassLoader.StaticData.
1259:                         systemPackageAssertionStatus.get(name);
1260:               name = getPackagePortion(name);
1261:             }
1262:           while (! "".equals(name) && status == null);
1263:         if (status != null)
1264:           return status.equals(Boolean.TRUE);
1265:       }
1266:     return c.defaultAssertionStatus;
1267:   }
1268: 
1269:   /**
1270:    * Like <code>getField(String)</code> but without the security checks and returns null
1271:    * instead of throwing NoSuchFieldException.
1272:    */
1273:   private Field internalGetField(String name)
1274:   {
1275:     Field[] fields = getDeclaredFields(true);
1276:     for (int i = 0; i < fields.length; i++)
1277:       {
1278:     Field field = fields[i];
1279:     if (field.getName().equals(name))
1280:       return field;
1281:       }
1282:     Class[] interfaces = getInterfaces();
1283:     for (int i = 0; i < interfaces.length; i++)
1284:       {
1285:     Field field = interfaces[i].internalGetField(name);
1286:     if(field != null)
1287:       return field;
1288:       }
1289:     Class superClass = getSuperclass();
1290:     if (superClass != null)
1291:       return superClass.internalGetField(name);
1292:     return null;
1293:   }
1294: 
1295:   /**
1296:    * Strip the last portion of the name (after the last dot).
1297:    *
1298:    * @param name the name to get package of
1299:    * @return the package name, or "" if no package
1300:    */
1301:   private static String getPackagePortion(String name)
1302:   {
1303:     int lastInd = name.lastIndexOf('.');
1304:     if (lastInd == -1)
1305:       return "";
1306:     return name.substring(0, lastInd);
1307:   }
1308: 
1309:   /**
1310:    * Perform security checks common to all of the methods that
1311:    * get members of this Class.
1312:    */
1313:   private void memberAccessCheck(int which)
1314:   {
1315:     SecurityManager sm = SecurityManager.current;
1316:     if (sm != null)
1317:       {
1318:     sm.checkMemberAccess(this, which);
1319:     Package pkg = getPackage();
1320:     if (pkg != null)
1321:       sm.checkPackageAccess(pkg.getName());
1322:       }
1323:   }
1324: }