Difference between revisions of "Collections"
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==Methods of Collection interface== | ==Methods of Collection interface== | ||
There are many methods declared in the Collection interface. They are as follows: | There are many methods declared in the Collection interface. They are as follows: | ||
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<tr><td>14</td><td>public int hashCode()</td><td>returns the hashcode number for collection.</td></tr> | <tr><td>14</td><td>public int hashCode()</td><td>returns the hashcode number for collection.</td></tr> | ||
</tbody></table> | </tbody></table> | ||
+ | |||
+ | ==Iterator interface== | ||
+ | Iterator interface provides the facility of iterating the elements in forward direction only. | ||
+ | |||
+ | ===Methods of Iterator interface=== | ||
+ | There are only three methods in the Iterator interface. They are: | ||
+ | |||
+ | <table class="alt"> | ||
+ | <tbody><tr><th>No.</th><th>Method</th><th>Description</th></tr> | ||
+ | <tr><td>1</td><td>public boolean hasNext()</td><td>It returns true if iterator has more elements.</td></tr> | ||
+ | <tr><td>2</td><td>public Object next()</td><td>It returns the element and moves the cursor pointer to the next element.</td></tr> | ||
+ | <tr><td>3</td><td>public void remove()</td><td>It removes the last elements returned by the iterator. It is rarely used.</td></tr> | ||
+ | </tbody></table> | ||
+ | |||
+ | |||
==[[Set]]== | ==[[Set]]== | ||
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===[[LinkedHashSet]]=== | ===[[LinkedHashSet]]=== | ||
===[[TreeSet]]=== | ===[[TreeSet]]=== | ||
+ | ===[[SortedSet]]=== | ||
==[[List]]== | ==[[List]]== | ||
+ | ===[[ArrayList]]=== | ||
+ | ===[[LinkedList]]=== | ||
+ | ===[[Vector]]=== | ||
+ | ===[[Stack]]=== | ||
+ | |||
+ | ==[[Queue]]== | ||
+ | ===[[PriorityQueue]]=== | ||
+ | ===[[Deque]]=== | ||
+ | ===[[ArrayDeque]]=== | ||
+ | |||
==[[Map]]== | ==[[Map]]== | ||
+ | ===[[HashMap]]=== | ||
+ | ====[[LinkedHashMap]]==== | ||
+ | ===[[IdentityHashMap]]=== | ||
+ | ===[[WeakHashMap]]=== | ||
+ | ===[[SortedMap]]=== | ||
+ | ====[[TreeMap]]==== | ||
+ | |||
+ | |||
==[[Generics]]== | ==[[Generics]]== | ||
Revision as of 07:14, 1 August 2018
Collections in java is a framework that provides an architecture to store and manipulate the group of objects.
All the operations that you perform on a data such as searching, sorting, insertion, manipulation, deletion etc. can be performed by Java Collections.
Java Collection simply means a single unit of objects. Java Collection framework provides many interfaces (Set, List, Queue, Deque etc.) and classes (ArrayList, Vector, LinkedList, PriorityQueue, HashSet, LinkedHashSet, TreeSet etc).
Contents
[hide]Methods of Collection interface
There are many methods declared in the Collection interface. They are as follows:
No. | Method | Description |
---|---|---|
1 | public boolean add(Object element) | is used to insert an element in this collection. |
2 | public boolean addAll(Collection c) | is used to insert the specified collection elements in the invoking collection. |
3 | public boolean remove(Object element) | is used to delete an element from this collection. |
4 | public boolean removeAll(Collection c) | is used to delete all the elements of specified collection from the invoking collection. |
5 | public boolean retainAll(Collection c) | is used to delete all the elements of invoking collection except the specified collection. |
6 | public int size() | return the total number of elements in the collection. |
7 | public void clear() | removes the total no of element from the collection. |
8 | public boolean contains(Object element) | is used to search an element. |
9 | public boolean containsAll(Collection c) | is used to search the specified collection in this collection. |
10 | public Iterator iterator() | returns an iterator. |
11 | public Object[] toArray() | converts collection into array. |
12 | public boolean isEmpty() | checks if collection is empty. |
13 | public boolean equals(Object element) | matches two collection. |
14 | public int hashCode() | returns the hashcode number for collection. |
Iterator interface
Iterator interface provides the facility of iterating the elements in forward direction only.
Methods of Iterator interface
There are only three methods in the Iterator interface. They are:
<tbody> </tbody>No. | Method | Description |
---|---|---|
1 | public boolean hasNext() | It returns true if iterator has more elements. |
2 | public Object next() | It returns the element and moves the cursor pointer to the next element. |
3 | public void remove() | It removes the last elements returned by the iterator. It is rarely used. |