Java Reference
In-Depth Information
All methods that need the notion of equivalence (such as contains and
remove ) use the equals method on the relevant objects.
The toArray method that has no parameters returns an array of Object .
You can use toArray(T[]) to create arrays of other types. For example, if
your collection contains String objects, you may want to create a String
array. The following code will do that:
String[] strings = new String[collection.size()];
strings = collection.toArray(strings);
Notice that strings is assigned the return value of toArray . This is to be
safe in case the size of the collection has increased since the array was
allocated, in which case the returned array will not be the one originally
allocated. You can also use an empty String array to pass in the desired
type and let toArray allocate an array of exactly the right size:
String[] strings = collection.toArray(new String[0]);
Several methods of Collection operate in bulk from another collection.
The methods are provided for convenience; also, a collection can often
operate more efficiently in bulk.
public boolean containsAll(Collection<?> coll)
Returns true if this collection contains each of the elements in
coll .
public boolean addAll(Collection<? extends E> coll)
Adds each element of coll to this collection, returning TRue if
any addition required changing the collection. (Optional)
public boolean removeAll(Collection<?> coll)
 
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