public class ArrayMultiSet extends AbstractCollection {

/** Array in which the elements in this multiset are stored. */

private E[] _store;

/** Array indices below this amount contain the active elements in this collection. */

private int _size;

/** Modification counter used to preserve the fail-fast nature of its iterators. */

private long _modCount;

/** Constant value used as the initial length of the backing store. */

private static final int DEFAULT_BACKING_STORE_LENGTH = 12;

/**

* Creates a new empty multiset.

*/

public ArrayMultiSet() {

_store = (E[]) new Object[DEFAULT_BACKING_STORE_LENGTH];

}

/**

* Update the multiset so that it includes all of the elements from before the call AND the given element.

*

* @param e Item to be added to this collection.

* @return True when the element was successfully added; false otherwise. This always returns true.

*/

@Override

public boolean add(E e) {

_store = getStoreWithSpace();

includeElement(e);

return true;

}

/**

* Checks if the backing store has a space in which another element can be stored. When there is no space, the method

* allocates an array with twice as much space, copies the existing elements into that new array, and then returns

* that new array. Otherwise, it returns the original backing store.

*/

private E[] getStoreWithSpace() {

}

/**

* Includes the element in the multiset while updating the instance variables so that the class invariant is

* preserved.

* Precondition: _store is guaranteed to have sufficient space for including the new element (preconditions are

* guaranteed to be true at the start)

*

* @param elem Element to be included in the multiset

*/

private void includeElement(E elem) {

}

@Override

public int size() {

return _size;

}

@Override

public boolean isEmpty() {

return _size == 0;

}

}

The first method is getstoreNithSpace().This method does not change_store. getstoreWithspace) checks if there is space in the backing store and (when it has space to include another element) returns store or (when store is full) returns a newly allocated array with an appropriate amount of space You will also need to implement includeElement(.includeElentupdates the instance variables so that the element is included in the instance