summaryrefslogtreecommitdiffstats
path: root/ridljar/com/sun/star/lib/uno/helper/InterfaceContainer.java
blob: e858ced81fd807d35de907d5b8ea8e1614ba902c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
/*
 * This file is part of the LibreOffice project.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * This file incorporates work covered by the following license notice:
 *
 *   Licensed to the Apache Software Foundation (ASF) under one or more
 *   contributor license agreements. See the NOTICE file distributed
 *   with this work for additional information regarding copyright
 *   ownership. The ASF licenses this file to you under the Apache
 *   License, Version 2.0 (the "License"); you may not use this file
 *   except in compliance with the License. You may obtain a copy of
 *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
 */

package com.sun.star.lib.uno.helper;

import java.util.Iterator;
import java.util.ListIterator;
import java.util.Collection;

import com.sun.star.lang.EventObject;
import com.sun.star.lang.XEventListener;
import com.sun.star.uno.UnoRuntime;

/**
 * This class is a container for interfaces.
 *
 * It is intended to be used as storage for UNO interface of a specific type.
 * The client has to ensure that the container contains only elements of the same
 * type. If one needs to store different types, then one uses OMultiTypeInterfaceContainer.
 * When the client calls disposeAndClear, the contained objects are queried for
 * com.sun.star.lang.XEventListener and disposing is called. Afterwards
 * the list cannot be used anymore.
 *
 * This list does not allow null values.
 * All methods are thread-safe. The same holds true for
 * iterators, issued by this class. Several iterators can exist at the same time and can also
 * be modified (java.util.ListIterator.add, java.util.ListIterator.remove etc.). To make this work,
 * the InterfaceContainer provides the iterators with copies of the list's data.
 * The add and remove calls on the iterator modify the data in the iterator's list as well as
 * in InterfaceContainer. Modification on InterfaceContainer, however, are not
 * synchronized with existing iterators. For example
 * <pre>
 * InterfaceContainer cont= new InterfaceContainer();
 * ListIterator it= cont.listIterator();
 *
 * cont.add( someInterface);
 * // one cannot obtain someInterface through iterator it,
 * // instead get a new iterator
 * it= cont.listIterator();
 * // it now keeps a fresh copy of cont and hence contains someInterface
 *
 * // Adding an interface on the iterator will cause the interface also to be added
 * // to InterfaceContainer
 * it.add( someOtherInterface);
 * // someOtherInterface is now in it and cont
 * ListIterator it2= cont.listIterator();
 * //someOtherInterface can also be obtained by all newly created iterators, e.g. it2.
 * </pre>
 *
 *  The add and remove methods of an iterator work on a particular location within a list,
 *  dependent on what the value of the iterator's cursor is. After the call the value at the
 *  appropriate position has been modified. Since the iterator received a copy of InterfaceContainer's
 *  data, InterfaceContainer may have been modified (by List methods or through other iterators).
 *  Therefore both data sets may not contain the same elements anymore. Consequently, a List method
 *  that modifies data, does not modify InterfaceContainer's data at a certain index
 *  (according to the iterators cursor). Instead, new elements are added at the end of list. When
 *  Iterator.remove is called, then the first occurrence of that element in InterfaceContainer
 *  is removed.
 *  ListIterator.set is not supported.
 *
 * A lot of  methods resemble those of the  to java.util.List interface, although
 * this class does not implement it. However, the list iterators returned, for example by
 * the listIterator method implement the java.util.ListIterator interface.
 * Implementing the List interface would mean to support all none - optional methods as
 * prescribed by the interface declaration. Among those is the subList method which returns
 * a range of values of the list's data wrapped in a List implementation. Changes to the sub
 * list have to cause changes in the main list. This is a problem, since this class is to be
 * used in a multi-threaded environment. The sub list could work on a copy as the iterators
 * do, but all the functions which work on a given index could not be properly supported.
 * Unfortunately, the List interface documentation states that all optional methods implemented
 * by the list have to be implemented in the sub list. That would mean to do without all those
 * critical methods, although they might work well in the "main list" (as opposed to sub list).
 */
public class InterfaceContainer implements Cloneable
{
    static final boolean DEBUG= false;
    /**
     * The array buffer into which the elements of the ArrayList are stored.
     * The capacity of the ArrayList is the length of this array buffer.
     */
    Object elementData[];

    /**
     * The size of the ArrayList (the number of elements it contains).
     */
    private int size;


    /** Creates a new instance of InterfaceContainer */
    public InterfaceContainer()
    {
        this(10);
    }
    /**
     * Constructs an empty list with the specified initial capacity.
     *
     * @param   initialCapacity   the initial capacity of the list.
     * @exception IllegalArgumentException if the specified initial capacity
     *            is negative
     */
    public InterfaceContainer(int initialCapacity)
    {
        if (initialCapacity < 0)
            throw new java.lang.IllegalArgumentException("Illegal Capacity: "+
            initialCapacity);
        this.elementData = new Object[initialCapacity];
    }

    private InterfaceContainer(Object[] data) {
        elementData = data;
        size = elementData == null ? 0 : elementData.length;
    }

    /**
     * Trims the capacity of this <code>ArrayList</code> instance to be the
     * list's current size.  An application can use this operation to minimize
     * the storage of an <code>ArrayList</code> instance.
     */
    synchronized public void trimToSize()
    {
        int oldCapacity = elementData.length;
        if (size < oldCapacity)
        {
            Object oldData[] = elementData;
            elementData = new Object[size];
            System.arraycopy(oldData, 0, elementData, 0, size);
        }
    }

    /**
     * Increases the capacity of this <code>ArrayList</code> instance, if
     * necessary, to ensure  that it can hold at least the number of elements
     * specified by the minimum capacity argument.
     *
     * @param   minCapacity   the desired minimum capacity.
     */
    synchronized public void ensureCapacity(int minCapacity)
    {
        int oldCapacity = elementData.length;
        if (minCapacity > oldCapacity)
        {
            Object oldData[] = elementData;
            int newCapacity = (oldCapacity * 3)/2 + 1;
            if (newCapacity < minCapacity)
                newCapacity = minCapacity;
            elementData = new Object[newCapacity];
            System.arraycopy(oldData, 0, elementData, 0, size);
        }
    }

    /**
     * Appends the specified element to the end of this list.
     *
     * @param o element to be appended to this list.
     * @return <code>true</code> (as per the general contract of Collection.add).
     */
    synchronized public boolean add(Object o)
    {
        boolean ret= false;
        if (elementData != null && o != null)
        {
            ensureCapacity(size + 1);  // Increments modCount!!
            elementData[size++] = o;
            ret= true;
        }
        return ret;
    }

    /**
     * Inserts the specified element at the specified position in this
     * list. Shifts the element currently at that position (if any) and
     * any subsequent elements to the right (adds one to their indices).
     *
     * @param index index at which the specified element is to be inserted.
     * @param element element to be inserted.
     * @throws    IndexOutOfBoundsException if index is out of range
     *        <code>(index &lt; 0 || index &gt; size())</code>.
     */
    synchronized public void add(int index, Object element)
    {
        if (elementData != null && element != null)
        {
            if (index > size || index < 0)
                throw new IndexOutOfBoundsException(
                "Index: "+index+", Size: "+size);

            ensureCapacity(size+1);
            System.arraycopy(elementData, index, elementData, index + 1,
            size - index);
            elementData[index] = element;
            size++;
        }
    }


    /**
     * Appends all of the elements in the specified Collection to the end of
     * this list, in the order that they are returned by the
     * specified Collection's Iterator.  The behavior of this operation is
     * undefined if the specified Collection is modified while the operation
     * is in progress.  (This implies that the behavior of this call is
     * undefined if the specified Collection is this list, and this
     * list is nonempty.)
     *
     * @param c the elements to be inserted into this list.
     * @throws    IndexOutOfBoundsException if index out of range <code>(index
     *        &lt; 0 || index &gt; size())</code>.
     * @return true if an element was inserted.
     */
    synchronized public boolean addAll(Collection c)
    {
        int numNew = c.size();
        ensureCapacity(size + numNew);

        Iterator e = c.iterator();
        for (int i=0; i<numNew; i++)
        {
            Object o= e.next();
            if (o != null)
                elementData[size++] = o;
        }
        return numNew != 0;
    }
    /**
     * Inserts all of the elements in the specified Collection into this
     * list, starting at the specified position.  Shifts the element
     * currently at that position (if any) and any subsequent elements to
     * the right (increases their indices).  The new elements will appear
     * in the list in the order that they are returned by the
     * specified Collection's iterator.
     *
     * @param index index at which to insert first element
     *          from the specified collection.
     * @param c elements to be inserted into this list.
     * @throws    IndexOutOfBoundsException if index out of range <code>(index
     *        &lt; 0 || index &gt; size())</code>.
     * @return true if an element was inserted.
     */
    synchronized public boolean addAll(int index, Collection c)
    {
        boolean ret= false;
        if (elementData != null)
        {
            if (index > size || index < 0)
                throw new IndexOutOfBoundsException(
                "Index: "+index+", Size: "+size);
            // only add  the non-null elements
            int sizeCol= c.size();
            Object[] arColl= new Object[sizeCol];
            Iterator icol= c.iterator();
            int curIndex= 0;
            for (int i=0; i < sizeCol; i++)
            {
                Object o= icol.next();
                if (o != null)
                    arColl[curIndex++]= o;
            }
            int numNew = curIndex;
            ensureCapacity(size + numNew);  // Increments modCount!!

            int numMoved = size - index;
            if (numMoved > 0)
                System.arraycopy(elementData, index, elementData, index + numNew,
                numMoved);

            for (int i=0; i<numNew; i++)
            {
                elementData[index++]= arColl[i];
            }
            size += numNew;
            ret= numNew != 0;
        }
        return ret;
    }

    /**
     * Removes all of the elements from this list.  The list will
     * be empty after this call returns.
     */
    synchronized public void clear()
    {
        if (elementData != null)
        {
            // Let gc do its work
            for (int i = 0; i < size; i++)
                elementData[i] = null;

            size = 0;
        }
    }
    /**
     * Returns <code>true</code> if this list contains the specified element.
     *
     * @param elem element whose presence in this List is to be tested.
     * @return <code>true</code> if this list contains the specified element.
     */
    synchronized public boolean contains(Object elem)
    {
        return indexOf(elem) >= 0;
    }

    synchronized public boolean containsAll(Collection collection)
    {
        boolean retVal= true;
        if (elementData != null && collection != null)
        {
            Iterator it= collection.iterator();
            while (it.hasNext())
            {
                Object obj= it.next();
                if (!contains(obj))
                {
                    retVal= false;
                    break;
                }
            }
        }
        return retVal;
    }
    /**
     * Returns the element at the specified position in this list.
     *
     * @param  index index of element to return.
     * @return the element at the specified position in this list.
     * @throws    IndexOutOfBoundsException if index is out of range <code>(index
     *        &lt; 0 || index &gt;= size())</code>.
     */
    synchronized public Object get(int index)
    {
        if (elementData != null)
        {
            RangeCheck(index);
            return elementData[index];
        }
        return null;
    }

    /**
     * Searches for the first occurrence of the given argument, testing
     * for equality using the <code>equals</code> method.
     *
     * @param   elem   an object.
     * @return  the index of the first occurrence of the argument in this
     *          list; returns <code>-1</code> if the object is not found.
     * @see     Object#equals(Object)
     */
    synchronized public int indexOf(Object elem)
    {
        if (elementData == null || elem == null) {
            return -1;
        }

        int index= -1;

        for (int i = 0; i < size; i++)
        {
            if (elem == elementData[i])
            {
                index= i;
                break;
            }
        }

        if (index == -1)
        {
            for (int i = 0; i < size; i++)
            {
                if (UnoRuntime.areSame(elem, elementData[i]))
                {
                    index= i;
                    break;
                }
            }
        }
        return index;
    }
    /**
     * Tests if this list has no elements.
     *
     * @return  <code>true</code> if this list has no elements;
     *          <code>false</code> otherwise.
     */
    synchronized public boolean isEmpty()
    {
        return size == 0;
    }

    synchronized public Iterator iterator()
    {
        if (elementData != null)
        {
            InterfaceContainer aCopy= (InterfaceContainer) clone();
            return new Itr(aCopy);
        }
        return null;
    }
    /**
     * Returns the index of the last occurrence of the specified object in
     * this list.
     *
     * @param   elem   the desired element.
     * @return  the index of the last occurrence of the specified object in
     *          this list; returns -1 if the object is not found.
     */
    synchronized public int lastIndexOf(Object elem)
    {
        if (elementData == null || elem == null) {
            return -1;
        }

        int index= -1;

        for (int i = size-1; i >= 0; i--)
        {
            if (elem == elementData[i])
            {
                index= i;
                break;
            }
        }
        if (index == -1)
        {
            for (int i = size-1; i >= 0; i--)
            {
                if (UnoRuntime.areSame(elem, elementData[i]))
                {
                    index= i;
                    break;
                }
            }
        }
        return index;
    }

    /**
     * Returns a shallow copy of this <code>ArrayList</code> instance. The contained
     * references are copied but the objects not.
     *
     * @return  a clone of this <code>List</code> instance.
     */
    @Override
    synchronized public Object clone()
    {
        Object[] data;
        if (elementData == null) {
            data = null;
        } else {
            data = new Object[size];
            System.arraycopy(elementData, 0, data, 0, size);
        }
        return new InterfaceContainer(data);
    }
    synchronized public ListIterator listIterator()
    {
        return listIterator(0);
    }

    /** The iterator keeps a copy of the list. Changes to InterfaceContainer do not
     *  affect the data of the iterator. Conversely, changes to the iterator are effect
     *  InterfaceContainer.
     *  @param index the starting offset into the list.
     *  @return a new iterator.
     */
    synchronized public ListIterator listIterator(int index)
    {
        if (elementData != null)
        {
            InterfaceContainer aCopy= (InterfaceContainer) clone();
            return new LstItr(aCopy, index);
        }
        return null;
    }
    /**
     * Removes the element at the specified position in this list.
     * Shifts any subsequent elements to the left (subtracts one from their
     * indices).
     *
     * @param index the index of the element to removed.
     * @return the element that was removed from the list.
     * @throws    IndexOutOfBoundsException if index out of range <code>(index
     *        &lt; 0 || index &gt;= size())</code>.
     */
    synchronized public Object remove(int index)
    {
        Object ret= null;
        if (elementData != null)
        {
            RangeCheck(index);
            ret= elementData[index];

            int numMoved = size - index - 1;
            if (numMoved > 0)
                System.arraycopy(elementData, index+1, elementData, index,
                numMoved);
            elementData[--size] = null; // Let gc do its work
        }
        return ret;
    }


    /** Parameter obj may... or may not. What did the original author want
     *  to tell us here?
     *  @param obj the object to be removed.
     *  @return true if obj was successfully removed from the list.
     */
    synchronized public boolean remove(Object obj)
    {
        boolean ret= false;
        if (elementData != null && obj != null)
        {
            int index= indexOf(obj);
            if (index != -1)
            {
                ret= true;
                remove(index);
            }
        }
        return ret;
    }

    synchronized public boolean removeAll(Collection collection)
    {
        boolean retVal= false;
        if (elementData != null && collection != null)
        {
            Iterator it= collection.iterator();
            while (it.hasNext())
            {
                Object obj= it.next();
                boolean bMod= remove( obj);
                if (bMod)
                    retVal= true;
            }
        }
        return retVal;
    }

    synchronized public boolean retainAll(Collection collection)
    {
        if (elementData == null || collection == null) {
            return false;
        }

        boolean retVal= false;
        // iterate over data
        Object[] arRetained= new Object[size];
        int indexRetained= 0;
        for(int i= 0; i < size; i++)
        {
            Object curElem= elementData[i];
            // try to find the element in collection
            Iterator itColl= collection.iterator();
            boolean bExists= false;
            while (itColl.hasNext())
            {
                if (curElem == itColl.next())
                {
                    // current element is in collection
                    bExists= true;
                    break;
                }
            }
            if (!bExists)
            {
                itColl= collection.iterator();
                while (itColl.hasNext())
                {
                    Object o= itColl.next();
                    if (o != null && UnoRuntime.areSame(o, curElem))
                    {
                        bExists= true;
                        break;
                    }
                }
            }
            if (bExists)
                arRetained[indexRetained++]= curElem;
        }
        retVal= size != indexRetained;
        if (indexRetained > 0)
        {
            elementData= arRetained;
            size= indexRetained;
        }
        return retVal;
    }


    /** Not supported.
     * @param index index of element to replace.
     * @param element element to be stored at the specified position.
     * @return the element previously at the specified position.
     * @throws    IndexOutOfBoundsException if index out of range
     *        <code>(index &lt; 0 || index &gt;= size())</code>.
     */
    synchronized public Object set(int index, Object element)
    {
          Object ret= null;
          if (elementData != null && element != null)
          {
              RangeCheck(index);
              ret = elementData[index];
              elementData[index] = element;
          }
          return ret;
    }

    /**
     * Returns the number of elements in this list.
     *
     * @return  the number of elements in this list.
     */
    synchronized public int size()
    {
        if (elementData != null)
            return size;
        return 0;
    }


    /**
     * Returns an array containing all of the elements in this list
     * in the correct order.
     *
     * @return an array containing all of the elements in this list
     *         in the correct order.
     */
    synchronized public Object[] toArray()
    {
        if (elementData != null)
        {
            Object[] result = new Object[size];
            System.arraycopy(elementData, 0, result, 0, size);
            return result;
        }
        return null;
    }

    /**
     * Returns an array containing all of the elements in this list in the
     * correct order.  The runtime type of the returned array is that of the
     * specified array.  If the list fits in the specified array, it is
     * returned therein.  Otherwise, a new array is allocated with the runtime
     * type of the specified array and the size of this list.<p>
     *
     * If the list fits in the specified array with room to spare (i.e., the
     * array has more elements than the list), the element in the array
     * immediately following the end of the collection is set to
     * <code>null</code>.  This is useful in determining the length of the list
     * <i>only</i> if the caller knows that the list does not contain any
     * <code>null</code> elements.
     *
     * @param a the array into which the elements of the list are to
     *      be stored, if it is big enough; otherwise, a new array of the
     *      same runtime type is allocated for this purpose.
     * @return an array containing the elements of the list.
     * @throws ArrayStoreException if the runtime type of a is not a supertype
     *         of the runtime type of every element in this list.
     */
    synchronized public Object[] toArray(Object a[])
    {
        if (a.length < size)
            a = (Object[])java.lang.reflect.Array.newInstance(
            a.getClass().getComponentType(), size);
        if (elementData != null)
            System.arraycopy(elementData, 0, a, 0, size);

        if (a.length > size)
            a[size] = null;

        return a;
    }

    /**
     * Check if the given index is in range.  If not, throw an appropriate
     * runtime exception.
     */
    private void RangeCheck(int index)
    {
        if (index >= size || index < 0)
            throw new IndexOutOfBoundsException(
            "Index: "+index+", Size: "+size);
    }

    public void disposeAndClear(EventObject evt)
    {
        Iterator aIt;
        synchronized (this)
        {
            aIt= iterator();
            // Release containers if new entries occur in disposing;
            // set the member to null, the iterator delete the values
            clear();
            elementData= null;
            size= 0;
        }
        if (aIt != null)
        {
            while( aIt.hasNext() )
            {
                try
                {
                    Object o= aIt.next();
                    XEventListener evtListener= UnoRuntime.queryInterface(
                    XEventListener.class, o);
                    if( evtListener != null )
                        evtListener.disposing( evt );
                }
                catch ( RuntimeException e)
                {
                    // be robust, if e.g. a remote bridge has disposed already.
                    // there is no way, to delegate the error to the caller :o(.
                }
            }
        }
    }


    private class Itr implements Iterator
    {
        InterfaceContainer dataIt;
        /**
         * Index of element to be returned by subsequent call to next.
         */
        int cursor= 0;
        /**
         * Index of element returned by most recent call to next or
         * previous.  Reset to -1 if this element is deleted by a call
         * to remove.
         */
        int lastRet = -1;

        /** The object that has been returned by most recent call to next
         *  or previous. Reset to null if this element is deleted by a call
         *  to remove.
         */
        Object lastRetObj= null;

        Itr(InterfaceContainer _data)
        {
            dataIt= _data;
        }

        synchronized public boolean hasNext()
        {
            return cursor !=dataIt.size();
        }

        public synchronized Object next()
        {
            try
            {
                Object next = dataIt.get(cursor);
                lastRet = cursor++;
                lastRetObj= next;
                return next;
            }
            catch(java.lang.IndexOutOfBoundsException e)
            {
                java.util.NoSuchElementException ex2 = new java.util.NoSuchElementException();
                ex2.initCause(e);
                throw ex2;
            }
        }

        /** Removes the interface from the list, that has been last returned by a
         *  call to next(). This is done according to the specification of the interface
         *  method. The element is also removed from InterfaceContainer but independent
         *  of the location. If the element is multiple times in InterfaceContainer then
         *  it is up to the java.util.ArrayList implementation what element is removed.
         */
        public synchronized void remove()
        {
            if (lastRet == -1)
                throw new IllegalStateException();
            // Remove the entry from InterfaceContainer.
            InterfaceContainer.this.remove(lastRetObj);
            dataIt.remove(lastRet);

            if (lastRet < cursor)
                cursor--;
            lastRet = -1;
            lastRetObj= null;
        }
    }

    private class LstItr extends Itr implements ListIterator
    {

        LstItr(InterfaceContainer _data, int _index)
        {
            super(_data);
            cursor= _index;
        }

        /** Inserts an element to the iterators list according to the specification
         *  of this interface method. The element is also added to InterfaceContainer
         *  but its location within the list cannot be guaranteed.
         */
        public synchronized void add(Object o)
        {
            InterfaceContainer.this.add(o);
            dataIt.add(cursor++, o);
            lastRet = -1;
            lastRetObj= null;
        }

        synchronized public boolean hasPrevious()
        {
            return cursor != 0;
        }

        synchronized public int nextIndex()
        {
            return cursor;
        }

        public synchronized Object previous()
        {
            try
            {
                Object previous = dataIt.get(--cursor);
                lastRet = cursor;
                lastRetObj= previous;
                return previous;
            } catch(IndexOutOfBoundsException e)
            {
                java.util.NoSuchElementException ex2 = new java.util.NoSuchElementException();
                ex2.initCause(e);
                throw ex2;
            }
        }

        synchronized public int previousIndex()
        {
            return cursor-1;
        }

        /** This is not possible since several iterators can modify InterfaceContainer
         */
        public synchronized void set(Object o)
        {
            throw new UnsupportedOperationException();
        }


    } // class LstItr
}