Examples of java.util.ConcurrentModificationException

java.util.ConcurrentModificationException
This exception may be thrown by methods that have detected concurrent modification of an object when such modification is not permissible.
For example, it is not generally permissible for one thread to modify a Collection while another thread is iterating over it. In general, the results of the iteration are undefined under these circumstances. Some Iterator implementations (including those of all the general purpose collection implementations provided by the JRE) may choose to throw this exception if this behavior is detected. Iterators that do this are known as fail-fast iterators, as they fail quickly and cleanly, rather that risking arbitrary, non-deterministic behavior at an undetermined time in the future.
Note that this exception does not always indicate that an object has been concurrently modified by a different thread. If a single thread issues a sequence of method invocations that violates the contract of an object, the object may throw this exception. For example, if a thread modifies a collection directly while it is iterating over the collection with a fail-fast iterator, the iterator will throw this exception.
Note that fail-fast behavior cannot be guaranteed as it is, generally speaking, impossible to make any hard guarantees in the presence of unsynchronized concurrent modification. Fail-fast operations throw ConcurrentModificationException on a best-effort basis. Therefore, it would be wrong to write a program that depended on this exception for its correctness: ConcurrentModificationException should be used only to detect bugs. @author Josh Bloch @version 1.20, 03/30/06 @see Collection @see Iterator @see ListIterator @see Vector @see LinkedList @see HashSet @see Hashtable @see TreeMap @see AbstractList @since 1.2

            @Override public E next () {
                checkForComodification();
                int ii = _cursor;
                if (ii >= _size) throw new NoSuchElementException();
                Object[] data = _data;
                if (ii >= data.length) throw new ConcurrentModificationException();
                _cursor = ii + 1;
                @SuppressWarnings("unchecked") E elem = (E) data[_lastRet = ii];
                return elem;
            }


            @Override public void remove () {
                if (_lastRet < 0) throw new IllegalStateException();
                checkForComodification();
                try {
                    DestroyableList.this.remove(_lastRet);
                    _cursor = _lastRet;
                    _lastRet = -1;
                    _exModCount = _modCount;
                } catch (IndexOutOfBoundsException ex) {
                    throw new ConcurrentModificationException();
                }
            }


            final void checkForComodification() {
                if (_modCount != _exModCount) throw new ConcurrentModificationException();
            }


            protected int _cursor;       // index of next element to return
            protected int _lastRet = -1; // index of last element returned; -1 if no such
            protected int _exModCount = _modCount;

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                int index=0;


                @Override
                public boolean hasNext() {
                    if(size() != startSize) {
                        throw new ConcurrentModificationException();
                    }
                    return index < values.size();
                }


                @Override

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  }


  public void editBegin( AbstractCompoundEdit ce )
  {
    if( currentEdit != null ) {
      throw new ConcurrentModificationException( "Concurrent editing" );
    }
    currentEdit    = ce;
    collEditByStart  = null;    // dispose ? XXXX
    collEditByStop  = null;    // dispose ? XXXX

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  {
    if( currentEdit == null ) {
      throw new IllegalStateException( "Missing editBegin" );
    }
    if( ce != currentEdit ) {
      throw new ConcurrentModificationException( "Concurrent editing" );
    }
  }

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         * @exception NoSuchElementException if there is no element left in the map
         */
        public int key()
            throws ConcurrentModificationException, NoSuchElementException {
            if (referenceCount != count) {
                throw new ConcurrentModificationException();
            }
            if (current < 0) {
                throw new NoSuchElementException();
            }
            return keys[current];

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         * @exception NoSuchElementException if there is no element left in the map
         */
        public T value()
            throws ConcurrentModificationException, NoSuchElementException {
            if (referenceCount != count) {
                throw new ConcurrentModificationException();
            }
            if (current < 0) {
                throw new NoSuchElementException();
            }
            return values[current];

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         */
        public void advance()
            throws ConcurrentModificationException, NoSuchElementException {


            if (referenceCount != count) {
                throw new ConcurrentModificationException();
            }


            // advance on step
            current = next;

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        public boolean remove(Object o) {
            synchronized (CopyOnWriteArrayList.this) {
                Object[] array = getArray();
                if (array != expectedArray)
                    throw new ConcurrentModificationException();
                int fullLength = array.length;
                int pos = search(array, o, offset, length);
                if (pos < 0) return false;
                Object[] newarr = new Object[fullLength - 1];
                int moved = length - pos - 1;

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                    throw new IndexOutOfBoundsException("Index: " + index +
                        ", Size: " + length);
                }
                Object[] oldarr = getArray();
                if (oldarr != expectedArray)
                    throw new ConcurrentModificationException();
                if (added == 0) return false;
                int fullLength = oldarr.length;
                Object[] newarr = new Object[fullLength + added];
                int pos = offset + index;
                int newpos = pos;

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        public boolean removeAll(Collection c) {
            if (c.isEmpty()) return false;
            synchronized (CopyOnWriteArrayList.this) {
                Object[] array = getArray();
                if (array != expectedArray)
                    throw new ConcurrentModificationException();
                int fullLength = array.length;
                Object[] tmp = new Object[length];
                int retained = 0;
                for (int i = offset; i < offset + length; i++) {
                    Object o = array[i];

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