nsIMutableArray

Consumers of nsIArray should not QueryInterface to nsIMutableArray unless they own the array.

As above, it is legal to add null elements to the array. Note also that null elements can be created as a side effect of insertElementAt(). Conversely, if insertElementAt() is never used, and null elements are never explicitly added to the array, then it is guaranteed that nsIArray.queryElementAt() will never return a null value.

Any of these methods may throw NS_ERROR_OUT_OF_MEMORY when the array must grow to complete the call, but the allocation fails.

Method overview

Methods

appendElement()

Append an element at the end of the array.

void appendElement(
  in nsISupports element,
  in boolean weak
);

Parameters

element

The element to append.

weak

Whether or not to store the element using a weak reference.

Exceptions thrown

NS_ERROR_FAILURE

When a weak reference is requested, but the element does not support nsIWeakReference.

clear()

Clear the entire array, releasing all stored objects.

void clear();

Parameters

None.

insertElementAt()

Insert an element at the given position, moving the element currently located in that position, and all elements in higher position, up by one.

void insertElementAt(
  in nsISupports element,
  in unsigned long index,
  in boolean weak
);

Parameters

element

The element to insert.

index

The position in the array: If the position is lower than the current length of the array, the elements at that position and onwards are bumped one position up. If the position is equal to the current length of the array, the new element is appended. An index lower than 0 or higher than the current length of the array is invalid and will be ignored.

weak

Whether or not to store the element using a weak reference.

Exceptions thrown

NS_ERROR_FAILURE

When a weak reference is requested, but the element does not support nsIWeakReference.

removeElementAt()

Remove an element at a specific position, moving all elements stored at a higher position down one. To remove a specific element, use nsIArray.indexOf() to find the index first, then call removeElementAt.

void removeElementAt(
  in unsigned long index
);

Parameters

index

The position of the item.

Replace the element at the given position.

void replaceElementAt(
  in nsISupports element,
  in unsigned long index,
  in boolean weak
);

Parameters

element

The new element to insert.

index

The position in the array. If the position is lower than the current length of the array, an existing element will be replaced. If the position is equal to the current length of the array, the new element is appended. If the position is higher than the current length of the array, empty elements are appended followed by the new element at the specified position. An index lower than 0 is invalid and will be ignored.

weak

Whether or not to store the new element using a weak reference.

Exceptions thrown

NS_ERROR_FAILURE

When a weak reference is requested, but the element does not support nsIWeakReference.

See Also

• nsIArray