src/share/classes/java/awt/ContainerOrderFocusTraversalPolicy.java

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 148         return ftp;
 149     }
 150 
 151     /*
 152      * Checks if a new focus cycle takes place and returns a Component to traverse focus to.
 153      * @param comp a possible focus cycle root or policy provider
 154      * @param traversalDirection the direction of the traversal
 155      * @return a Component to traverse focus to if {@code comp} is a root or provider
 156      *         and implicit down-cycle is set, otherwise {@code null}
 157      */
 158     private Component getComponentDownCycle(Component comp, int traversalDirection) {
 159         Component retComp = null;
 160 
 161         if (comp instanceof Container) {
 162             Container cont = (Container)comp;
 163 
 164             if (cont.isFocusCycleRoot()) {
 165                 if (getImplicitDownCycleTraversal()) {
 166                     retComp = cont.getFocusTraversalPolicy().getDefaultComponent(cont);
 167 
 168                     if (retComp != null && log.isLoggable(PlatformLogger.FINE)) {
 169                         log.fine("### Transfered focus down-cycle to " + retComp +
 170                                  " in the focus cycle root " + cont);
 171                     }
 172                 } else {
 173                     return null;
 174                 }
 175             } else if (cont.isFocusTraversalPolicyProvider()) {
 176                 retComp = (traversalDirection == FORWARD_TRAVERSAL ?
 177                            cont.getFocusTraversalPolicy().getDefaultComponent(cont) :
 178                            cont.getFocusTraversalPolicy().getLastComponent(cont));
 179 
 180                 if (retComp != null && log.isLoggable(PlatformLogger.FINE)) {
 181                     log.fine("### Transfered focus to " + retComp + " in the FTP provider " + cont);
 182                 }
 183             }
 184         }
 185         return retComp;
 186     }
 187 
 188     /**
 189      * Returns the Component that should receive the focus after aComponent.
 190      * aContainer must be a focus cycle root of aComponent or a focus traversal policy provider.
 191      * <p>
 192      * By default, ContainerOrderFocusTraversalPolicy implicitly transfers
 193      * focus down-cycle. That is, during normal forward focus traversal, the
 194      * Component traversed after a focus cycle root will be the focus-cycle-
 195      * root's default Component to focus. This behavior can be disabled using
 196      * the <code>setImplicitDownCycleTraversal</code> method.
 197      * <p>
 198      * If aContainer is <a href="doc-files/FocusSpec.html#FocusTraversalPolicyProviders">focus
 199      * traversal policy provider</a>, the focus is always transferred down-cycle.
 200      *
 201      * @param aContainer a focus cycle root of aComponent or a focus traversal policy provider
 202      * @param aComponent a (possibly indirect) child of aContainer, or
 203      *        aContainer itself
 204      * @return the Component that should receive the focus after aComponent, or
 205      *         null if no suitable Component can be found
 206      * @throws IllegalArgumentException if aContainer is not a focus cycle
 207      *         root of aComponent or focus traversal policy provider, or if either aContainer or
 208      *         aComponent is null
 209      */
 210     public Component getComponentAfter(Container aContainer, Component aComponent) {
 211         if (log.isLoggable(PlatformLogger.FINE)) {
 212             log.fine("### Searching in " + aContainer + " for component after " + aComponent);
 213         }
 214 
 215         if (aContainer == null || aComponent == null) {
 216             throw new IllegalArgumentException("aContainer and aComponent cannot be null");
 217         }
 218         if (!aContainer.isFocusTraversalPolicyProvider() && !aContainer.isFocusCycleRoot()) {
 219             throw new IllegalArgumentException("aContainer should be focus cycle root or focus traversal policy provider");
 220 
 221         } else if (aContainer.isFocusCycleRoot() && !aComponent.isFocusCycleRoot(aContainer)) {
 222             throw new IllegalArgumentException("aContainer is not a focus cycle root of aComponent");
 223         }
 224 
 225         synchronized(aContainer.getTreeLock()) {
 226 
 227             if (!(aContainer.isVisible() && aContainer.isDisplayable())) {
 228                 return null;
 229             }
 230 
 231             // Before all the ckecks below we first see if it's an FTP provider or a focus cycle root.
 232             // If it's the case just go down cycle (if it's set to "implicit").
 233             Component comp = getComponentDownCycle(aComponent, FORWARD_TRAVERSAL);
 234             if (comp != null) {
 235                 return comp;
 236             }
 237 
 238             // See if the component is inside of policy provider.
 239             Container provider = getTopmostProvider(aContainer, aComponent);
 240             if (provider != null) {
 241                 if (log.isLoggable(PlatformLogger.FINE)) {
 242                     log.fine("### Asking FTP " + provider + " for component after " + aComponent);
 243                 }
 244 
 245                 // FTP knows how to find component after the given. We don't.
 246                 FocusTraversalPolicy policy = provider.getFocusTraversalPolicy();
 247                 Component afterComp = policy.getComponentAfter(provider, aComponent);
 248 
 249                 // Null result means that we overstepped the limit of the FTP's cycle.
 250                 // In that case we must quit the cycle, otherwise return the component found.
 251                 if (afterComp != null) {
 252                     if (log.isLoggable(PlatformLogger.FINE)) {
 253                         log.fine("### FTP returned " + afterComp);
 254                     }
 255                     return afterComp;
 256                 }
 257                 aComponent = provider;
 258             }
 259 
 260             List<Component> cycle = getFocusTraversalCycle(aContainer);
 261 
 262             if (log.isLoggable(PlatformLogger.FINE)) {
 263                 log.fine("### Cycle is " + cycle + ", component is " + aComponent);
 264             }
 265 
 266             int index = getComponentIndex(cycle, aComponent);
 267 
 268             if (index < 0) {
 269                 if (log.isLoggable(PlatformLogger.FINE)) {
 270                     log.fine("### Didn't find component " + aComponent + " in a cycle " + aContainer);
 271                 }
 272                 return getFirstComponent(aContainer);
 273             }
 274 
 275             for (index++; index < cycle.size(); index++) {
 276                 comp = cycle.get(index);
 277                 if (accept(comp)) {
 278                     return comp;
 279                 } else if ((comp = getComponentDownCycle(comp, FORWARD_TRAVERSAL)) != null) {
 280                     return comp;
 281                 }
 282             }
 283 
 284             if (aContainer.isFocusCycleRoot()) {
 285                 this.cachedRoot = aContainer;
 286                 this.cachedCycle = cycle;
 287 
 288                 comp = getFirstComponent(aContainer);
 289 


 314     public Component getComponentBefore(Container aContainer, Component aComponent) {
 315         if (aContainer == null || aComponent == null) {
 316             throw new IllegalArgumentException("aContainer and aComponent cannot be null");
 317         }
 318         if (!aContainer.isFocusTraversalPolicyProvider() && !aContainer.isFocusCycleRoot()) {
 319             throw new IllegalArgumentException("aContainer should be focus cycle root or focus traversal policy provider");
 320 
 321         } else if (aContainer.isFocusCycleRoot() && !aComponent.isFocusCycleRoot(aContainer)) {
 322             throw new IllegalArgumentException("aContainer is not a focus cycle root of aComponent");
 323         }
 324 
 325         synchronized(aContainer.getTreeLock()) {
 326 
 327             if (!(aContainer.isVisible() && aContainer.isDisplayable())) {
 328                 return null;
 329             }
 330 
 331             // See if the component is inside of policy provider.
 332             Container provider = getTopmostProvider(aContainer, aComponent);
 333             if (provider != null) {
 334                 if (log.isLoggable(PlatformLogger.FINE)) {
 335                     log.fine("### Asking FTP " + provider + " for component after " + aComponent);
 336                 }
 337 
 338                 // FTP knows how to find component after the given. We don't.
 339                 FocusTraversalPolicy policy = provider.getFocusTraversalPolicy();
 340                 Component beforeComp = policy.getComponentBefore(provider, aComponent);
 341 
 342                 // Null result means that we overstepped the limit of the FTP's cycle.
 343                 // In that case we must quit the cycle, otherwise return the component found.
 344                 if (beforeComp != null) {
 345                     if (log.isLoggable(PlatformLogger.FINE)) {
 346                         log.fine("### FTP returned " + beforeComp);
 347                     }
 348                     return beforeComp;
 349                 }
 350                 aComponent = provider;
 351 
 352                 // If the provider is traversable it's returned.
 353                 if (accept(aComponent)) {
 354                     return aComponent;
 355                 }
 356             }
 357 
 358             List<Component> cycle = getFocusTraversalCycle(aContainer);
 359 
 360             if (log.isLoggable(PlatformLogger.FINE)) {
 361                 log.fine("### Cycle is " + cycle + ", component is " + aComponent);
 362             }
 363 
 364             int index = getComponentIndex(cycle, aComponent);
 365 
 366             if (index < 0) {
 367                 if (log.isLoggable(PlatformLogger.FINE)) {
 368                     log.fine("### Didn't find component " + aComponent + " in a cycle " + aContainer);
 369                 }
 370                 return getLastComponent(aContainer);
 371             }
 372 
 373             Component comp = null;
 374             Component tryComp = null;
 375 
 376             for (index--; index>=0; index--) {
 377                 comp = cycle.get(index);
 378                 if (comp != aContainer && (tryComp = getComponentDownCycle(comp, BACKWARD_TRAVERSAL)) != null) {
 379                     return tryComp;
 380                 } else if (accept(comp)) {
 381                     return comp;
 382                 }
 383             }
 384 
 385             if (aContainer.isFocusCycleRoot()) {
 386                 this.cachedRoot = aContainer;
 387                 this.cachedCycle = cycle;


 394                 return comp;
 395             }
 396         }
 397         return null;
 398     }
 399 
 400     /**
 401      * Returns the first Component in the traversal cycle. This method is used
 402      * to determine the next Component to focus when traversal wraps in the
 403      * forward direction.
 404      *
 405      * @param aContainer the focus cycle root or focus traversal policy provider whose first
 406      *        Component is to be returned
 407      * @return the first Component in the traversal cycle of aContainer,
 408      *         or null if no suitable Component can be found
 409      * @throws IllegalArgumentException if aContainer is null
 410      */
 411     public Component getFirstComponent(Container aContainer) {
 412         List<Component> cycle;
 413 
 414         if (log.isLoggable(PlatformLogger.FINE)) {
 415             log.fine("### Getting first component in " + aContainer);
 416         }
 417         if (aContainer == null) {
 418             throw new IllegalArgumentException("aContainer cannot be null");
 419 
 420         }
 421 
 422         synchronized(aContainer.getTreeLock()) {
 423 
 424             if (!(aContainer.isVisible() && aContainer.isDisplayable())) {
 425                 return null;
 426             }
 427 
 428             if (this.cachedRoot == aContainer) {
 429                 cycle = this.cachedCycle;
 430             } else {
 431                 cycle = getFocusTraversalCycle(aContainer);
 432             }
 433 
 434             if (cycle.size() == 0) {
 435                 if (log.isLoggable(PlatformLogger.FINE)) {
 436                     log.fine("### Cycle is empty");
 437                 }
 438                 return null;
 439             }
 440             if (log.isLoggable(PlatformLogger.FINE)) {
 441                 log.fine("### Cycle is " + cycle);
 442             }
 443 
 444             for (Component comp : cycle) {
 445                 if (accept(comp)) {
 446                     return comp;
 447                 } else if (comp != aContainer &&
 448                            (comp = getComponentDownCycle(comp, FORWARD_TRAVERSAL)) != null)
 449                 {
 450                     return comp;
 451                 }
 452             }
 453         }
 454         return null;
 455     }
 456 
 457     /**
 458      * Returns the last Component in the traversal cycle. This method is used
 459      * to determine the next Component to focus when traversal wraps in the
 460      * reverse direction.
 461      *
 462      * @param aContainer the focus cycle root or focus traversal policy provider whose last
 463      *        Component is to be returned
 464      * @return the last Component in the traversal cycle of aContainer,
 465      *         or null if no suitable Component can be found
 466      * @throws IllegalArgumentException if aContainer is null
 467      */
 468     public Component getLastComponent(Container aContainer) {
 469         List<Component> cycle;
 470         if (log.isLoggable(PlatformLogger.FINE)) {
 471             log.fine("### Getting last component in " + aContainer);
 472         }
 473 
 474         if (aContainer == null) {
 475             throw new IllegalArgumentException("aContainer cannot be null");
 476         }
 477 
 478         synchronized(aContainer.getTreeLock()) {
 479 
 480             if (!(aContainer.isVisible() && aContainer.isDisplayable())) {
 481                 return null;
 482             }
 483 
 484             if (this.cachedRoot == aContainer) {
 485                 cycle = this.cachedCycle;
 486             } else {
 487                 cycle = getFocusTraversalCycle(aContainer);
 488             }
 489 
 490             if (cycle.size() == 0) {
 491                 if (log.isLoggable(PlatformLogger.FINE)) {
 492                     log.fine("### Cycle is empty");
 493                 }
 494                 return null;
 495             }
 496             if (log.isLoggable(PlatformLogger.FINE)) {
 497                 log.fine("### Cycle is " + cycle);
 498             }
 499 
 500             for (int i= cycle.size() - 1; i >= 0; i--) {
 501                 Component comp = cycle.get(i);
 502                 if (accept(comp)) {
 503                     return comp;
 504                 } else if (comp instanceof Container && comp != aContainer) {
 505                     Container cont = (Container)comp;
 506                     if (cont.isFocusTraversalPolicyProvider()) {
 507                         return cont.getFocusTraversalPolicy().getLastComponent(cont);
 508                     }
 509                 }
 510             }
 511         }
 512         return null;
 513     }
 514 
 515     /**
 516      * Returns the default Component to focus. This Component will be the first




 148         return ftp;
 149     }
 150 
 151     /*
 152      * Checks if a new focus cycle takes place and returns a Component to traverse focus to.
 153      * @param comp a possible focus cycle root or policy provider
 154      * @param traversalDirection the direction of the traversal
 155      * @return a Component to traverse focus to if {@code comp} is a root or provider
 156      *         and implicit down-cycle is set, otherwise {@code null}
 157      */
 158     private Component getComponentDownCycle(Component comp, int traversalDirection) {
 159         Component retComp = null;
 160 
 161         if (comp instanceof Container) {
 162             Container cont = (Container)comp;
 163 
 164             if (cont.isFocusCycleRoot()) {
 165                 if (getImplicitDownCycleTraversal()) {
 166                     retComp = cont.getFocusTraversalPolicy().getDefaultComponent(cont);
 167 
 168                     if (retComp != null && log.isLoggable(PlatformLogger.Level.FINE)) {
 169                         log.fine("### Transfered focus down-cycle to " + retComp +
 170                                  " in the focus cycle root " + cont);
 171                     }
 172                 } else {
 173                     return null;
 174                 }
 175             } else if (cont.isFocusTraversalPolicyProvider()) {
 176                 retComp = (traversalDirection == FORWARD_TRAVERSAL ?
 177                            cont.getFocusTraversalPolicy().getDefaultComponent(cont) :
 178                            cont.getFocusTraversalPolicy().getLastComponent(cont));
 179 
 180                 if (retComp != null && log.isLoggable(PlatformLogger.Level.FINE)) {
 181                     log.fine("### Transfered focus to " + retComp + " in the FTP provider " + cont);
 182                 }
 183             }
 184         }
 185         return retComp;
 186     }
 187 
 188     /**
 189      * Returns the Component that should receive the focus after aComponent.
 190      * aContainer must be a focus cycle root of aComponent or a focus traversal policy provider.
 191      * <p>
 192      * By default, ContainerOrderFocusTraversalPolicy implicitly transfers
 193      * focus down-cycle. That is, during normal forward focus traversal, the
 194      * Component traversed after a focus cycle root will be the focus-cycle-
 195      * root's default Component to focus. This behavior can be disabled using
 196      * the <code>setImplicitDownCycleTraversal</code> method.
 197      * <p>
 198      * If aContainer is <a href="doc-files/FocusSpec.html#FocusTraversalPolicyProviders">focus
 199      * traversal policy provider</a>, the focus is always transferred down-cycle.
 200      *
 201      * @param aContainer a focus cycle root of aComponent or a focus traversal policy provider
 202      * @param aComponent a (possibly indirect) child of aContainer, or
 203      *        aContainer itself
 204      * @return the Component that should receive the focus after aComponent, or
 205      *         null if no suitable Component can be found
 206      * @throws IllegalArgumentException if aContainer is not a focus cycle
 207      *         root of aComponent or focus traversal policy provider, or if either aContainer or
 208      *         aComponent is null
 209      */
 210     public Component getComponentAfter(Container aContainer, Component aComponent) {
 211         if (log.isLoggable(PlatformLogger.Level.FINE)) {
 212             log.fine("### Searching in " + aContainer + " for component after " + aComponent);
 213         }
 214 
 215         if (aContainer == null || aComponent == null) {
 216             throw new IllegalArgumentException("aContainer and aComponent cannot be null");
 217         }
 218         if (!aContainer.isFocusTraversalPolicyProvider() && !aContainer.isFocusCycleRoot()) {
 219             throw new IllegalArgumentException("aContainer should be focus cycle root or focus traversal policy provider");
 220 
 221         } else if (aContainer.isFocusCycleRoot() && !aComponent.isFocusCycleRoot(aContainer)) {
 222             throw new IllegalArgumentException("aContainer is not a focus cycle root of aComponent");
 223         }
 224 
 225         synchronized(aContainer.getTreeLock()) {
 226 
 227             if (!(aContainer.isVisible() && aContainer.isDisplayable())) {
 228                 return null;
 229             }
 230 
 231             // Before all the ckecks below we first see if it's an FTP provider or a focus cycle root.
 232             // If it's the case just go down cycle (if it's set to "implicit").
 233             Component comp = getComponentDownCycle(aComponent, FORWARD_TRAVERSAL);
 234             if (comp != null) {
 235                 return comp;
 236             }
 237 
 238             // See if the component is inside of policy provider.
 239             Container provider = getTopmostProvider(aContainer, aComponent);
 240             if (provider != null) {
 241                 if (log.isLoggable(PlatformLogger.Level.FINE)) {
 242                     log.fine("### Asking FTP " + provider + " for component after " + aComponent);
 243                 }
 244 
 245                 // FTP knows how to find component after the given. We don't.
 246                 FocusTraversalPolicy policy = provider.getFocusTraversalPolicy();
 247                 Component afterComp = policy.getComponentAfter(provider, aComponent);
 248 
 249                 // Null result means that we overstepped the limit of the FTP's cycle.
 250                 // In that case we must quit the cycle, otherwise return the component found.
 251                 if (afterComp != null) {
 252                     if (log.isLoggable(PlatformLogger.Level.FINE)) {
 253                         log.fine("### FTP returned " + afterComp);
 254                     }
 255                     return afterComp;
 256                 }
 257                 aComponent = provider;
 258             }
 259 
 260             List<Component> cycle = getFocusTraversalCycle(aContainer);
 261 
 262             if (log.isLoggable(PlatformLogger.Level.FINE)) {
 263                 log.fine("### Cycle is " + cycle + ", component is " + aComponent);
 264             }
 265 
 266             int index = getComponentIndex(cycle, aComponent);
 267 
 268             if (index < 0) {
 269                 if (log.isLoggable(PlatformLogger.Level.FINE)) {
 270                     log.fine("### Didn't find component " + aComponent + " in a cycle " + aContainer);
 271                 }
 272                 return getFirstComponent(aContainer);
 273             }
 274 
 275             for (index++; index < cycle.size(); index++) {
 276                 comp = cycle.get(index);
 277                 if (accept(comp)) {
 278                     return comp;
 279                 } else if ((comp = getComponentDownCycle(comp, FORWARD_TRAVERSAL)) != null) {
 280                     return comp;
 281                 }
 282             }
 283 
 284             if (aContainer.isFocusCycleRoot()) {
 285                 this.cachedRoot = aContainer;
 286                 this.cachedCycle = cycle;
 287 
 288                 comp = getFirstComponent(aContainer);
 289 


 314     public Component getComponentBefore(Container aContainer, Component aComponent) {
 315         if (aContainer == null || aComponent == null) {
 316             throw new IllegalArgumentException("aContainer and aComponent cannot be null");
 317         }
 318         if (!aContainer.isFocusTraversalPolicyProvider() && !aContainer.isFocusCycleRoot()) {
 319             throw new IllegalArgumentException("aContainer should be focus cycle root or focus traversal policy provider");
 320 
 321         } else if (aContainer.isFocusCycleRoot() && !aComponent.isFocusCycleRoot(aContainer)) {
 322             throw new IllegalArgumentException("aContainer is not a focus cycle root of aComponent");
 323         }
 324 
 325         synchronized(aContainer.getTreeLock()) {
 326 
 327             if (!(aContainer.isVisible() && aContainer.isDisplayable())) {
 328                 return null;
 329             }
 330 
 331             // See if the component is inside of policy provider.
 332             Container provider = getTopmostProvider(aContainer, aComponent);
 333             if (provider != null) {
 334                 if (log.isLoggable(PlatformLogger.Level.FINE)) {
 335                     log.fine("### Asking FTP " + provider + " for component after " + aComponent);
 336                 }
 337 
 338                 // FTP knows how to find component after the given. We don't.
 339                 FocusTraversalPolicy policy = provider.getFocusTraversalPolicy();
 340                 Component beforeComp = policy.getComponentBefore(provider, aComponent);
 341 
 342                 // Null result means that we overstepped the limit of the FTP's cycle.
 343                 // In that case we must quit the cycle, otherwise return the component found.
 344                 if (beforeComp != null) {
 345                     if (log.isLoggable(PlatformLogger.Level.FINE)) {
 346                         log.fine("### FTP returned " + beforeComp);
 347                     }
 348                     return beforeComp;
 349                 }
 350                 aComponent = provider;
 351 
 352                 // If the provider is traversable it's returned.
 353                 if (accept(aComponent)) {
 354                     return aComponent;
 355                 }
 356             }
 357 
 358             List<Component> cycle = getFocusTraversalCycle(aContainer);
 359 
 360             if (log.isLoggable(PlatformLogger.Level.FINE)) {
 361                 log.fine("### Cycle is " + cycle + ", component is " + aComponent);
 362             }
 363 
 364             int index = getComponentIndex(cycle, aComponent);
 365 
 366             if (index < 0) {
 367                 if (log.isLoggable(PlatformLogger.Level.FINE)) {
 368                     log.fine("### Didn't find component " + aComponent + " in a cycle " + aContainer);
 369                 }
 370                 return getLastComponent(aContainer);
 371             }
 372 
 373             Component comp = null;
 374             Component tryComp = null;
 375 
 376             for (index--; index>=0; index--) {
 377                 comp = cycle.get(index);
 378                 if (comp != aContainer && (tryComp = getComponentDownCycle(comp, BACKWARD_TRAVERSAL)) != null) {
 379                     return tryComp;
 380                 } else if (accept(comp)) {
 381                     return comp;
 382                 }
 383             }
 384 
 385             if (aContainer.isFocusCycleRoot()) {
 386                 this.cachedRoot = aContainer;
 387                 this.cachedCycle = cycle;


 394                 return comp;
 395             }
 396         }
 397         return null;
 398     }
 399 
 400     /**
 401      * Returns the first Component in the traversal cycle. This method is used
 402      * to determine the next Component to focus when traversal wraps in the
 403      * forward direction.
 404      *
 405      * @param aContainer the focus cycle root or focus traversal policy provider whose first
 406      *        Component is to be returned
 407      * @return the first Component in the traversal cycle of aContainer,
 408      *         or null if no suitable Component can be found
 409      * @throws IllegalArgumentException if aContainer is null
 410      */
 411     public Component getFirstComponent(Container aContainer) {
 412         List<Component> cycle;
 413 
 414         if (log.isLoggable(PlatformLogger.Level.FINE)) {
 415             log.fine("### Getting first component in " + aContainer);
 416         }
 417         if (aContainer == null) {
 418             throw new IllegalArgumentException("aContainer cannot be null");
 419 
 420         }
 421 
 422         synchronized(aContainer.getTreeLock()) {
 423 
 424             if (!(aContainer.isVisible() && aContainer.isDisplayable())) {
 425                 return null;
 426             }
 427 
 428             if (this.cachedRoot == aContainer) {
 429                 cycle = this.cachedCycle;
 430             } else {
 431                 cycle = getFocusTraversalCycle(aContainer);
 432             }
 433 
 434             if (cycle.size() == 0) {
 435                 if (log.isLoggable(PlatformLogger.Level.FINE)) {
 436                     log.fine("### Cycle is empty");
 437                 }
 438                 return null;
 439             }
 440             if (log.isLoggable(PlatformLogger.Level.FINE)) {
 441                 log.fine("### Cycle is " + cycle);
 442             }
 443 
 444             for (Component comp : cycle) {
 445                 if (accept(comp)) {
 446                     return comp;
 447                 } else if (comp != aContainer &&
 448                            (comp = getComponentDownCycle(comp, FORWARD_TRAVERSAL)) != null)
 449                 {
 450                     return comp;
 451                 }
 452             }
 453         }
 454         return null;
 455     }
 456 
 457     /**
 458      * Returns the last Component in the traversal cycle. This method is used
 459      * to determine the next Component to focus when traversal wraps in the
 460      * reverse direction.
 461      *
 462      * @param aContainer the focus cycle root or focus traversal policy provider whose last
 463      *        Component is to be returned
 464      * @return the last Component in the traversal cycle of aContainer,
 465      *         or null if no suitable Component can be found
 466      * @throws IllegalArgumentException if aContainer is null
 467      */
 468     public Component getLastComponent(Container aContainer) {
 469         List<Component> cycle;
 470         if (log.isLoggable(PlatformLogger.Level.FINE)) {
 471             log.fine("### Getting last component in " + aContainer);
 472         }
 473 
 474         if (aContainer == null) {
 475             throw new IllegalArgumentException("aContainer cannot be null");
 476         }
 477 
 478         synchronized(aContainer.getTreeLock()) {
 479 
 480             if (!(aContainer.isVisible() && aContainer.isDisplayable())) {
 481                 return null;
 482             }
 483 
 484             if (this.cachedRoot == aContainer) {
 485                 cycle = this.cachedCycle;
 486             } else {
 487                 cycle = getFocusTraversalCycle(aContainer);
 488             }
 489 
 490             if (cycle.size() == 0) {
 491                 if (log.isLoggable(PlatformLogger.Level.FINE)) {
 492                     log.fine("### Cycle is empty");
 493                 }
 494                 return null;
 495             }
 496             if (log.isLoggable(PlatformLogger.Level.FINE)) {
 497                 log.fine("### Cycle is " + cycle);
 498             }
 499 
 500             for (int i= cycle.size() - 1; i >= 0; i--) {
 501                 Component comp = cycle.get(i);
 502                 if (accept(comp)) {
 503                     return comp;
 504                 } else if (comp instanceof Container && comp != aContainer) {
 505                     Container cont = (Container)comp;
 506                     if (cont.isFocusTraversalPolicyProvider()) {
 507                         return cont.getFocusTraversalPolicy().getLastComponent(cont);
 508                     }
 509                 }
 510             }
 511         }
 512         return null;
 513     }
 514 
 515     /**
 516      * Returns the default Component to focus. This Component will be the first