Collection interface

The collection interface is the foundation upon which the collection framework is built. It declares the core methods that all collections will have. A class cast exception is generated when are objects is incompatible with another, Such as when an attempt is made to add an incompatible object to a collection. The following are methods defined in the collection interface.

Boolean add (object obj):

Adds object to the invoking collection. Returns true if object was added to the collection. Return false if object is already a member of the collection, or if the collection does not allow duplicates.

Boolean add all (collection c):

Adds all the elements of c to the invoking collection, Return true if the elements were added otherwise, return false.

Void clear ():

In this removes all the elements from the invoking collection.

Boolean contains (object obj):

Return true if object is an element of the invoking collection, otherwise return false.

Boolean contains all (collecton c):

Return true if the invoking collections contains all elements of c, otherwise return false.

Boolean equals (object obj):

Returns true if the invoking collection and object are equal, otherwise return false.

Int hash code ():

In this returns the hash code for the invoking collection.

Boolean is empty ():

Returns true if the invoking collection is empty, otherwise, return false.

Boolean remove:

Remove one instance of object from the invoking collection and returns true if the elements were removed, else return false.

Boolean removes all (collection c):

Removes all the elements from the invoking collection except those in c. Returns’ true if the elements were removed, otherwise returns false.

Boolean retain all:

Removes all elements from the invoking collection except those in c. return true, if the elements were removed otherwise, return false.

Int size ():

Returns the number of elements held in the invoking collection.

Collection Interface Homework Help