java.util.ConcurrentModificationException 解决 Android

An ConcurrentModificationException is thrown when a Collection is modified and an existing iterator on the Collection is used to modify the Collection as well.

An iterator over a sequence of objects, such as a collection.

If a collection has been changed since the iterator was created, methods next and hasNext() may throw a ConcurrentModificationException. It is not possible to guarantee that this mechanism works in all cases of unsynchronized concurrent modification. It should only be used for debugging purposes. Iterators with this behavior are called fail-fast iterators.

Implementing Iterable and returning an Iterator allows your class to be used as a collection with the enhanced for loop.

    /**
     * Returns a new array containing all elements contained in this
     * {@code ArrayList}.
     *
     * @return an array of the elements from this {@code ArrayList}
     */
    @Override public Object[] toArray() {
        int s = size;
        Object[] result = new Object[s];
        System.arraycopy(array, 0, result, 0, s);
        return result;
    }