Java Collection Framework - Collection Interface

The Collection interface is used to represent any group of ojects, or elements. Here is a list of the public methods of the Collection Interface.

boolean

add (Object o)
Ensures that this collection contains the specified element (optional operation).

 boolean

addAll(Collection c)
Adds all of the elements in the specified collection to this collection (optional operation).

 void

clear()
Removes all of the elements from this collection (optional operation).

 boolean

contains(Object o)
Returns true if this collection contains the specified element.

 boolean

containsAll(Collection c)
Returns true if this collection contains all of the elements in the specified collection.

 boolean

equals(Object o)
Compares the specified object with this collection for equality.

 int

hashCode()
Returns the hash code value for this collection.

 boolean

isEmpty()
Returns true if this collection contains no elements.

 Iterator

iterator()
Returns an iterator over the elements in this collection.

 boolean

remove(Object o)
Removes a single instance of the specified element from this collection, if it is present (optional operation).

 boolean

removeAll(Collection c)
Removes all this collection's elements that are also contained in the specified collection (optional operation).

 boolean

retainAll(Collection c)
Retains only the elements in this collection that are contained in the specified collection (optional operation).

 int

size()
Returns the number of elements in this collection.

 Object[]

toArray()
Returns an array containing all of the elements in this collection.

 Object[]

toArray(Object[] a)
Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array.

The interface supports basic operations like adding and removing. When you try to remove an element, only a single instance of the element in the collection is removed, if present.

boolean add (Object o)
boolean remove(Object o)

The Collection interface also supports query operations

int size()
boolean isEmpty()
boolean contains(Object o)
Iterator iterator()


Explore the other Interface and Classes of Java Collection Framework

Collection Interface
Iterator Interface
Set Interface
List Interface
ListIterator Interface
Map Interface
SortedSet Interface
SortedMap Interface
HashSet & TreeSet Classes
ArrayList & LinkedList Classes
HashMap & Treemap Classes
Vector and Stack Classes

 
 

Collection Framework
Collection Interface
Iterator Interface
Set Interface
List Interface
ListIterator Interface
Map Interface
SortedSet Interface
SortedMap Interface
HashSet & TreeSet Classes
ArrayList & LinkedList Classes

HashMap & Treemap Classes
Vector & Stack Classes

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