Java Collection Interface

• Collection is an interface inwards java.
• Collection interface extends Iterable interface.
• In hierarchy, Collection interface is rootage of List, Queue together with Set interfaces.

• It represents unit of measurement of its elements. i.e. grouping of objects.
• Some collections produce non permit duplicate elements exactly about allows duplicate elements.
• Collection interface is base of operations on which collection framework is built.
• Collection interface contains basic functioning methods every bit bellow.

• boolean add(E element) - To brand certain that this collection contains the specified element. It volition supply truthful if object is added to collection. Return imitation if object is already at that spot together with collection does non permit duplicates.
• boolean contains(Object element) - It volition supply truthful if collection already accept specified element.
• boolean isEmpty() - Return truthful if collection is empty.
• Iterator<E> iterator() - It volition supply an iterator for the invoking collection.
• boolean remove(Object element) - It volition take away unmarried instance of given chemical part from collection. Return truthful if it is introduce else it volition supply false.
• int size() - It volition supply seat out of elements introduce inwards invoking collection.

•  Collection interface besides contains methods that operate on entire collections every bit bellow.

• boolean addAll(Collection<? extends E> c) - It volition add together all elements of c to the invoking collection. Return truthful if functioning was success else it volition supply false.
• boolean containsAll(Collection<?> c) - It volition supply truthful if this collection contains all the elements of specified collection.
• void clear() - It volition take away all the elements from invoking collection.
• boolean removeAll(Collection<?> c) - It volition take away all those elements from invoking collection which are available inwards c. It volition supply truthful if given elements removed else it volition supply false.
• boolean retainAll(Collection<?> c) - Retains all the elements inwards invoking collection which are available inwards c.

• Also at that spot are methods to perform array operations every bit bellow.

• Object[] toArray() - Return array of elements from invoking collection.
• <T> T[] toArray(T[] a) - Return array of all those elements from collection.

Basic Example of Collection

package JAVAExamples;  import java.util.ArrayList; import java.util.Collection; import java.util.LinkedList;  world shape CollectionExample {   world static void main(String[] args) {    // Collection ArrayList.   Collection<String> c1 = novel ArrayList<String>();   // Add items inwards ArrayList.   c1.add("ArrayList Item 1");   c1.add("ArrayList Item 2");   c1.add("ArrayList Item 3");   c1.add("ArrayList Item 4");   // Get collection Items list.   System.out.println("Collection Items are : " + c1);   // Get size of collection.   System.out.println("Size of collection is : " + c1.size());   // Remove exceptional from collection.   c1.remove("ArrayList Item 3");   System.out.println("Collection Items are : " + c1);    System.out.println();   System.out.println();           // Collection LinkedList.   Collection<String> c2 = novel LinkedList<String>();   // Add items inwards LinkedList.   c2.add("LinkedList Item 1");   c2.add("LinkedList Item 2");   c2.add("LinkedList Item 3");   c2.add("LinkedList Item 4");   // Get collection Items list.   System.out.println("Collection Items are : " + c2);   // Get size of collection.   System.out.println("Size of collection is : " + c2.size());   // Remove exceptional from collection.   c2.clear();   System.out.println("Collection Items are : " + c2);  } }

Output :

Collection Items are : [ArrayList Item 1, ArrayList Item 2, ArrayList Item 3, ArrayList Item 4] Size of collection is : four Collection Items are : [ArrayList Item 1, ArrayList Item 2, ArrayList Item 4]   Collection Items are : [LinkedList Item 1, LinkedList Item 2, LinkedList Item 3, LinkedList Item 4] Size of collection is : four Collection Items are : []

So this is basic regard of rootage collection interface. We volition larn dissimilar nestling interfaces of collection interface i past times i to buy the farm regard nearly how collection interface works.

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Java Listing Interface

• List interface inwards coffee is ordered collection then it tin shop elements inwards sequence.
• List interface is sub interface too it extends to Collection interface.
• List interface tin concur duplicate elements then you lot tin insert duplicate elements too.
• You tin access elements from listing past times integer index.
• Collection framework has many interfaces inwards coffee too listing interface is ane of them.
• List interface provides ListIterator to traverse through elements listing inwards backward too frontward directions.

Few by too large used methods inwards listing interface are equally bellow.

• void add(int index,Object element) : It volition insert chemical cistron at specified index seat inwards list.
• boolean addAll(int index,Collection c) : It volition add together all elements of given collection inwards to the listing at specified index position.
• object get(int Index ) : It volition render object at specified index seat from list.
• object set(int index,Object element) : It volition assign object at specified index seat inwards list.
• object remove(int index) : It volition take away object from specified position.
• ListIterator listIterator() : It volition returns the listing iterator at start of invoking list.
• ListIterator listIterator(int x) : It volition returns the listing iterator at specified index seat inwards list.
• int indexOf(Object obj) : It volition render index of rootage illustration of object from invoking list.
• int lastIndexOf(Object obj) : It volition render index of concluding illustration of object from invoking list.

List interface is implemented past times many classes similar Arraylist, Linkedlist too Vector.  Here, I accept represented illustration of listing interface using few methods from dissimilar degree implementation.

package JAVAExamples;  import java.util.ArrayList; import java.util.LinkedList; import java.util.List; import java.util.ListIterator;  populace degree InterfaceList {   populace static void main(String[] args) {   // Add elements inwards ArrayList.   List al = novel ArrayList();   al.add("New York");   al.add("Delhi");   al.add("Tokyo");      // Print arraylist elements.   System.out.println("ArrayList Elements");   System.out.print(al);   System.out.println();    // Add elements inwards linkedlist.   List ll = novel LinkedList();   ll.add("New York");   ll.add("Delhi");   ll.add("Tokyo");      // Print linkedlist elements.   System.out.println();   System.out.println("LinkedList Elements");   System.out.print(ll);   System.out.println();    // Get too impress arraylist's third element.   System.out.println();   System.out.println("Element at third seat inwards arralist is : " + al.get(2));    // Using ListIterator to traverse through frontward too backward directions inwards arralist.   ListIterator<String> itrtr = al.listIterator();    // Traverse inwards frontward direction.   System.out.println();   System.out.println("Traversing through arralist elements inwards frontward direction...");   piece (itrtr.hasNext()) {    System.out.println(itrtr.next());   }    // Traverse inwards backward direction.   System.out.println();   System.out.println("Traversing through arralist elements inwards backward direction...");   piece (itrtr.hasPrevious()) {    System.out.println(itrtr.previous());   }  } }

Output

ArrayList Elements [New York, Delhi, Tokyo]  LinkedList Elements [New York, Delhi, Tokyo]  Element at third seat inwards arralist is : Tokyo  Traversing through arralist elements inwards frontward direction... New York Delhi Tokyo  Traversing through arralist elements inwards backward direction... Tokyo Delhi New York

In higher upwardly illustration you lot tin encounter how arralist, linkedlist, croak method too listiterator works.

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Java Collections Framework

What is Java Collections Framework?

Java Collections Framework is grouping of dissimilar interfaces, classes as well as algorithms. In uncomplicated word, Collection agency unmarried unit of measurement of objects as well as framework agency skilful architecture. It is best architecture to shop grouping of reusable objects as well as manipulate them. Collection framework has many dissimilar interfaces, their sub interfaces as well as classes, their classes as well as sub classes. All the interfaces as well as classes has dissimilar purpose. You tin perform add, edit, delete, search, sort, etc operations on grouping of objects equally per class's methods as well as implementation.

Main Advantages Of Collection Framework

• Main payoff of collection framework is it volition reduces your programming efforts equally at that spot are stimulate made interfaces, classes as well as their methods which you lot tin utilisation straight inwards your programme to perform performance on object collection. 
• Collection is good construction framework as well as then you lot code lineament as well as speed volition hold out increased.
• Anyone tin utilisation collection real easily equally it's interfaces, classes as well as methods real tardily to sympathize as well as use.

Interfaces as well as Classes of Collection Framework

Collection, Set, List, Queue, Deque, SortedSet, Map as well as SortedMap are essence interfaces of collection framework. Detailed description of collection framework's interfaces as well as it's classes is given on below given pages.

• Java Collection Interface
• Java List Interface
• Java ArrayList Class
• LinkedList In Java
• Vector Class In Java
• Stack Class inwards Java
• Java Queue Interface
• Java PriorityQueue Class
• Java Deque Interface
• Java ArrayDeque Class
• Java Set Interface And Methods
• Java LinkedHashSet Class
• HashSet inwards Java Collection Example
• Java SortedSet Interface
• Java TreeSet Class
• Java Hashtable Class
• Java Map Interface
• Java HashMap Class
• LinkedHashMap Class In Java

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Java Arraylist Class

• ArrayList course of teaching is sub course of teaching of collection interface which implements to List interface.
• ArrayList course of teaching provides resizable-array thus it tin grow automatically every bit per requirement which resolves fixed Array limitation where you lot convey to pre-define the size of array.
• It tin agree zippo elements too.
• It is non synchronized implementation thus if multiple threads accessing it concurrently in addition to whatsoever ane from them modifies the entry in addition to then it must live synchronized externally.
• Also it tin agree duplicate elements.

Important methods of ArrayList course of teaching are every bit below.

• boolean add(E e) : It volition append given chemical component division at the cease of this ArrayList.
• void add(int index, due east element) : It volition add together specified chemical component division at the given index inwards list.
• boolean addAll(Collection<? extends E> c) : It volition append all the elements of given collection at the cease of array list. Appending fellowship volition live every bit per returned yesteryear collection's iterator.
• boolean addAll(int index, Collection<? extends E> c) : It volition insert all elements of specified collection inwards ArrayList starting from given index.
• void clear() : It volition clear List yesteryear removing all elements from it.
• Object clone() : It volition render shallow re-create of ArrayList.
• boolean contains(Object o) : It volition render truthful if given chemical component division is acquaint inwards list.
• void ensureCapacity(int minCapacity) : It volition increases the capacity of array listing if required to brand certain that it tin shop the elements every bit per given minCapacity argument.
• E get(int index) : It volition decease chemical component division from specified inced from array list.
• int indexOf(Object o) : It volition render the index of specified object(first occurrence) from array list.
• boolean isEmpty() : It volition banking concern jibe in addition to render truthful if array listing is empty.
• Iterator<E> iterator() : It volition render an iterator over the elements from array list.
• int lastIndexOf(Object o) : It volition render index of terminal occurrence of specified element.
• ListIterator<E> listIterator() : It volition render the listing iterator over the elements of array list.
• ListIterator<E> listIterator(int index) : It volition render the listing iterator over the elements of array listing starting from specified index.
• E remove(int index) : It volition take chemical component division from array listing which is stored at specified index.
• boolean remove(Object o) : It volition take specified element(first occurrence) from array list.
• boolean removeAll(Collection<?> c) : It volition take all elements from listing which are specified inwards given collection.
• protected void removeRange(int fromIndex, int toIndex) : It volition take elements from listing starting from fromIndex to toIndex.
• boolean retainAll(Collection<?> c) : It volition retain exclusively those elements inwards array listing which are specified inwards given collection.
• E set(int index, due east element) : It volition supervene upon given chemical component division inwards array listing at specified position.
• int size() : It volition render size of array list.
• List<E> subList(int fromIndex, int toIndex) : It volition render sub listing of elements from this listing starting from fromIndex(inclusive) to toIndex(exclusive).
• Object[] toArray() :It volition render proper sequential array of all array listing elements.
• void trimToSize() :It volition cut size of array listing every bit per it's electrical flow size.

Below given event volition demo you lot exercise of ArrayList class's unlike methods.

ArrayListExample

package JAVAExamples;  import java.util.ArrayList; import java.util.Iterator;  populace course of teaching ArrayListClassExample {   populace static void main(String[] args) {   // Create array list.   ArrayList<String> a = novel ArrayList<String>();   // Add elements inwards array list.   a.add("one");   a.add("two");   a.add("three");   a.add("four");   a.add("one");   a.add("six");   a.add("seven");   a.add("eight");    //Iterating over the arraylist elements.   Iterator itr = a.iterator();   System.out.println("ArrayList items are : ");   piece (itr.hasNext()) {    System.out.println(itr.next());   }      //Add special at specified index.   a.add(5, "nine");   System.out.println("Now ArrayList items are : "+a);      //Get special from specified index.   System.out.println("Item at index 6 is : "+a.get(6));      //Remove special from array list.   a.remove("three");   System.out.println("Now ArrayList items are : "+a);      //Get index of chemical component division from array list.   System.out.println("Index of ane is : "+a.indexOf("one"));      //Get terminal index of chemical component division from array list.   System.out.println("Last Index of ane is : "+a.lastIndexOf("one"));  } }

Output :

ArrayList items are :  ane ii iii iv ane 6 7 8 Now ArrayList items are : [one, two, three, four, one, nine, six, seven, eight] Item at index 6 is : 6 Now ArrayList items are : [one, two, four, one, nine, six, seven, eight] Index of ane is : 0 Last Index of ane is : 3

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Java Priorityqueue Class

• PriorityQueue Class is 1 of the collection framework degree which implements Queue, Serializable, Iterable too Collection interfaces.
• It is using natural ordering to lodge thus elements of PriorityQueue.Or elements volition hold out ordered based on Comparator provided at queue construction fourth dimension depending on which constructor is used.
• PriorityQueue is based on a priority heap. Heap is tree based information construction where all the nodes of tree are inward a specific order. Please read almost Heap to larn how it works.
• PriorityQueue does non permit non-comparable objects too it may throw ClassCastException if you lot volition endeavour to create so.
• PriorityQueue does non permit zippo elements every bit well.
• PriorityQueue implementation is non synchronized. So multiple threads should non access it concurrently.

Few methods which are used alongside PriorityQueue are every bit below.

• boolean add(E e) : It volition insert specified chemical constituent inward PriorityQueue.
• void clear() : It volition take away all elements from it to clear PriorityQueue.
• boolean contains(Object o) : It volition banking corporation lucifer too render truthful if specified chemical constituent is available inward PriorityQueue. Else it volition render false.
• boolean offer(E e) : It volition insert specified chemical constituent inward PriorityQueue.
• E peek() : It volition render head(first) of the chemical constituent from queue. If PriorityQueue is empty thus it volition render null.
• E poll() : It volition take away head(first) of the chemical constituent from queue. If PriorityQueue is empty thus it volition render null.
• boolean remove(Object o) : It volition take away specified element's unmarried event from PriorityQueue if it is present.
• int size() : It volition render size of PriorityQueue.
• Object[] toArray() : It volition render elements array from queue.
• <T> T[] toArray(T[] a) : It volition render elements array from queue. The runtime type of the returned array is that of the specified array.

Below given instance volition demo you lot how to operate PriorityQueue methods.

PriorityQueueExample :

package JAVAExamples;  import java.util.PriorityQueue;  populace degree PriorityQueueExample {   populace static void main(String[] args) {   //Create PriorityQueue.   PriorityQueue q=new PriorityQueue();   //Add items to PriorityQueue.   q.add("one");   q.add("two");   q.add("three");   q.add("four");   q.add("five");   q.add("six");   q.add("seven");      //Get size of PriorityQueue.   System.out.println("Size of PriorityQueue is : "+q.size());      //Print values of PriorityQueue.   System.out.println("PriorityQueue elements are : "+q);      //Get caput of PriorityQueue.   System.out.println("Head of PriorityQueue is : "+q.peek());      //Remove caput of PriorityQueue.   q.poll();   System.out.println("Now PriorityQueue elements are : "+q);    } }

Output :

Size of PriorityQueue is : 7 PriorityQueue elements are : [five, four, seven, two, one, three, six] Head of PriorityQueue is : 5 Now PriorityQueue elements are : [four, one, seven, two, six, three]

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Java Deque Interface

• Deque is 1 of the collection interface which extends Queue interface.
• Deque is linear collection which allow us to add together together with take chemical cistron from both ends of the queue.
• It is "double ended queue" that's why it is called Deque together with commonly pronounced equally "deck".
• Deque has dissimilar methods to perform insert, delete together with bear witness the chemical cistron inward queue.
• Each of these methods convey 2 dissimilar forms. One volition throw an exception if it fails during performance together with other volition furnish a particular value similar naught or false.

Different methods of Deque interface are described below.

• boolean add(E e) : It volition insert specified chemical cistron at the tail of this deque if infinite is currently available. Return truthful if performance is success or throw an IllegalStateException if fails to perform operation.
• void addFirst(E e) : It volition insert specified chemical cistron at the get-go of the queue.
• void addLast(E e) : It volition insert specified chemical cistron at the destination of the queue.
• boolean contains(Object o) : It volition furnish truthful if specified chemical cistron is available inward queue.
• E element() : It volition yell back head(first) chemical cistron from queue.
• E getFirst() : It volition yell back inaugural of all chemical cistron from queue.
• E getLast() : It volition yell back concluding chemical cistron from queue.
• boolean offer(E e) : It volition insert specified chemical cistron at the tail of this deque. It volition furnish truthful if success together with faux if performance fails.
• boolean offerFirst(E e) : It volition insert specified chemical cistron at the get-go of queue if infinite is available.
• boolean offerLast(E e) : It volition insert specified chemical cistron at the destination of queue if infinite is available.
• E peek() : It volition yell back head(first) chemical cistron from queue. Returns naught if queue is empty.
• E peekFirst() : It volition yell back inaugural of all chemical cistron from queue. Returns naught if queue is empty.
• E peekLast() : It volition yell back concluding chemical cistron from queue. Returns naught if queue is empty.
• E poll() : It volition take head(first) chemical cistron from queue. Returns naught if queue is empty.
• E pollFirst() : It volition take inaugural of all chemical cistron from queue. Returns naught if queue is empty.
• E pollLast() : It volition take concluding chemical cistron from queue. Returns naught if queue is empty.
• E pop() : It volition pops the chemical cistron from queue.
• void push(E e) : It volition pushes the chemical cistron onto queue. It volition furnish truthful on success together with throe an exception if performance fails.
• E remove() : It volition take inaugural of all chemical cistron from queue.
• boolean remove(Object o) : It volition take inaugural of all occurrence of the given chemical cistron from queue.
• E removeFirst() : It volition take inaugural of all chemical cistron from queue.
• boolean removeFirstOccurrence(Object o) : It volition take inaugural of all occurrence of the given chemical cistron from queue.
• E removeLast() : It volition take concluding chemical cistron from queue.
• boolean removeLastOccurrence(Object o) : It volition take concluding occurrence of the given chemical cistron from queue.
• int size() : It volition furnish size of queue.

I convey prepared representative of ArrayDeque to explore you lot how dissimilar methods of Deque works. Also you lot tin work LinkedList() using Deque.

Deque Example

package JAVAExamples;  import java.util.ArrayDeque; import java.util.Deque;  world flat DequeExample {   world static void main(String[] args) {   //Create ArrayDeque.   Deque<String> d = novel ArrayDeque<String>();   //Add elements inward Deque.   d.add("one");   d.add("two");   d.add("three");   d.add("four");   d.add("five");   d.add("four");   d.add("six");   //Print Deque elements.   System.out.println("Deque elements are : "+d);      //Add chemical cistron at inaugural of all of Deque.   d.addFirst("First Added");   System.out.println("Deque elements afterwards addFirst are : "+d);      //Add chemical cistron at concluding of Deque.   d.addLast("Last Added");   System.out.println("Deque elements afterwards addLast are : "+d);      //Get inaugural of all chemical cistron from Deque.   System.out.println("First chemical cistron inward deque is : "+d.getFirst());      //Get concluding chemical cistron from Deque.   System.out.println("Last chemical cistron inward deque is : "+d.getLast());      //Get inaugural of all chemical cistron from Deque using peek.   System.out.println("First chemical cistron inward deque using peek is : "+d.peek());      //Get concluding chemical cistron from Deque using peekLast.   System.out.println("Last chemical cistron inward deque using peekLast is : "+d.peekLast());      //Remove inaugural of all chemical cistron from deque.   d.removeFirst();   System.out.println("Deque elements afterwards removeFirst are  : "+d);      //Using pop.   d.pop();   System.out.println("Deque elements afterwards popular are  : "+d);      //Using push.   d.push("First");   System.out.println("Deque elements afterwards force are  : "+d);      //Remove LastOccurrence of chemical cistron from deque using removeLastOccurrence.   d.removeLastOccurrence("four");   System.out.println("Deque elements afterwards removeLastOccurrence are  : "+d);      //Get size of deque.   System.out.println("Size of Deque is  : "+d.size());  } }

Output :

Deque elements are : [one, two, three, four, five, four, six] Deque elements afterwards addFirst are : [First Added, one, two, three, four, five, four, six] Deque elements afterwards addLast are : [First Added, one, two, three, four, five, four, six, Last Added] First chemical cistron inward deque is : First Added Last chemical cistron inward deque is : Last Added First chemical cistron inward deque using peek is : First Added Last chemical cistron inward deque using peekLast is : Last Added Deque elements afterwards removeFirst are  : [one, two, three, four, five, four, six, Last Added] Deque elements afterwards popular are  : [two, three, four, five, four, six, Last Added] Deque elements afterwards force are  : [First, two, three, four, five, four, six, Last Added] Deque elements afterwards removeLastOccurrence are  : [First, two, three, four, five, six, Last Added] Size of Deque is  : 7

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Java Arraydeque Class

• ArrayDeque is ane of the collection framework fellow member which implements Deque, Cloneable together with Serializable interfaces.
• ArrayDeque provides Resizable-array implementation thus it has no capacity restrictions together with it volition grow every bit per requirement.
• In the absence of external synchronization, they are non thread safe. So they produce non permit multiple threads to access it concurrently.
• Also ArrayDequenot permit to shop zip elements.
• ArrayDeque Class is faster than LinkedList when used every bit a queue together with faster than Stack when used every bit a stack.
• If ArrayDeque is modified afterward the iterator creation together with if it is non modified past times iterators ain method together with then it volition throw ConcurrentModificationException. So inwards concurrent modification, Iterator volition fail.

Important methods of ArrayDeque Class

• boolean add(E e) : It volition insert given chemical share inwards ArrayDeque.
• void addFirst(E e) : It volition add together given chemical share at the kickoff of ArrayDeque.
• void addLast(E e) : It volition add together given chemical share at the destination of ArrayDeque.
• void clear() : It volition take away all elements from ArrayDeque to clear it.
• ArrayDeque<E> clone() : It volition render re-create of ArrayDeque.
• boolean contains(Object o) : It volition render truthful if specified chemical share available inwards ArrayDeque.
• Iterator<E> descendingIterator() : It volition render iterator inwards contrary sequential social club over the elements of ArrayDeque.
• E element() : It volition croak head(first) chemical share from this ArrayDeque.
• E getFirst() : It volition croak head(first) chemical share from this ArrayDeque.
• E getLast() : It volition croak concluding chemical share from this ArrayDeque.
• boolean isEmpty() : It volition render truthful if ArrayDeque is empty.
• boolean offer(E e) : It volition insert specified chemical share at the destination of this ArrayDeque.
• boolean offerFirst(E e) : It volition insert specified chemical share at the kickoff of this ArrayDeque.
• boolean offerLast(E e) : It volition insert specified chemical share at the destination of this ArrayDeque.
• E peek() : It volition recall together with render caput chemical share from ArrayDeque. Return zip if ArrayDeque is empty.
• E peekFirst() : It volition recall together with render head(first) chemical share from ArrayDeque. Return zip if ArrayDeque is empty.
• E peekLast() : It volition recall together with render concluding chemical share from ArrayDeque. Return zip if ArrayDeque is empty.
• E poll() : It volition take away caput chemical share from ArrayDeque. Return zip if ArrayDeque is empty.
• E pollFirst() : It volition take away head(first) chemical share from ArrayDeque. Return zip if ArrayDeque is empty.
• E pollLast() : It volition take away concluding chemical share from ArrayDeque. Return zip if ArrayDeque is empty.
• E pop() : It volition popular an chemical share from stack represented past times this ArrayDeque.
• void push(E e) : It volition pushes an chemical share on stack represented past times this ArrayDeque.
• E remove() : It volition take away caput chemical share of the ArrayDeque.
• boolean remove(Object o) : It volition take away unmarried illustration of specified object from ArrayDeque.
• E removeFirst() : It volition take away firstly chemical share from ArrayDeque.
• boolean removeFirstOccurrence(Object o) : It volition take away firstly occurrence of the chemical share from ArrayDeque.
• E removeLast() : It volition take away concluding chemical share from ArrayDeque.
• boolean removeLastOccurrence(Object o) : It volition take away concluding occurrence of the chemical share from ArrayDeque.
• int size() :It volition render size of ArrayDeque.
• Object[] toArray() : It volition render elements array from ArrayDeque.
• <T> T[] toArray(T[] a) : It volition render elements array from ArrayDeque. The runtime type of the returned array is that of the specified array.

Below given illustration volition exhibit you lot demo of higher upwardly ArrayDeque  method's usage.

ArrayDeque Example

package JAVAExamples;  import java.util.ArrayDeque; import java.util.Deque;  populace shape ArrayDequeExample {   populace static void main(String[] args) {   // Create ArrayDeque.   ArrayDeque<String> d = novel ArrayDeque<String>();   // Add elements inwards Deque.   d.add("one");   d.add("two");   d.add("three");   d.add("four");   d.add("five");   d.add("four");   d.add("six");   // Print Deque elements.   System.out.println("Deque elements are : " + d);    // Add chemical share at firstly of Deque.   d.addFirst("First Added");   System.out.println("Deque elements afterward addFirst are : " + d);    // Add chemical share at concluding of Deque.   d.addLast("Last Added");   System.out.println("Deque elements afterward addLast are : " + d);    // Get firstly chemical share from Deque.   System.out.println("First chemical share inwards deque is : " + d.getFirst());    // Get concluding chemical share from Deque.   System.out.println("Last chemical share inwards deque is : " + d.getLast());    // Get firstly chemical share from Deque using peek.   System.out.println("First chemical share inwards deque using peek is : " + d.peek());    // Get concluding chemical share from Deque using peekLast.   System.out.println("Last chemical share inwards deque using peekLast is : " + d.peekLast());    // Remove firstly chemical share from deque.   d.removeFirst();   System.out.println("Deque elements afterward removeFirst are  : " + d);    // Using pop.   d.pop();   System.out.println("Deque elements afterward popular are  : " + d);    // Using push.   d.push("First");   System.out.println("Deque elements afterward force are  : " + d);    // Remove LastOccurrence of chemical share from deque using removeLastOccurrence.   d.removeLastOccurrence("four");   System.out.println("Deque elements afterward removeLastOccurrence are  : "+ d);    // Get size of deque.   System.out.println("Size of Deque is  : " + d.size());  } }

Output :

Deque elements are : [one, two, three, four, five, four, six] Deque elements afterward addFirst are : [First Added, one, two, three, four, five, four, six] Deque elements afterward addLast are : [First Added, one, two, three, four, five, four, six, Last Added] First chemical share inwards deque is : First Added Last chemical share inwards deque is : Last Added First chemical share inwards deque using peek is : First Added Last chemical share inwards deque using peekLast is : Last Added Deque elements afterward removeFirst are  : [one, two, three, four, five, four, six, Last Added] Deque elements afterward popular are  : [two, three, four, five, four, six, Last Added] Deque elements afterward force are  : [First, two, three, four, five, four, six, Last Added] Deque elements afterward removeLastOccurrence are  : [First, two, three, four, five, six, Last Added] Size of Deque is  : 7

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Java Hashtable Class

• Hashtable Class implements Map, Cloneable in addition to Serializable interfaces in addition to likewise extends Dictionary class.
• It maps keys to values inwards tabular array format. Every fundamental is linked to it's value.
• In Hashtable, whatever object which is not naught volition last used every bit a fundamental or it's value.
• Initial capacity in addition to charge gene are 2 parameters of Hashtable that deport upon its performance.
• Meaning of capacity is the release of buckets inwards Hashtable in addition to Meaning of initial capacity is release of buckets inwards Hashtable at the fourth dimension of its creation.
• Load gene is parameter which mensurate how much amount Hashtable is in addition to when to increment it's capacity automatically.
• In social club to successfully cry back in addition to shop object inwards Hashtable, the object which is used every bit fundamental must implement the equals in addition to the hashCode methods.

Important methods of Hashtable Class are given below.

• void clear() : It volition take all fundamental in addition to it's values from Hashtable.
• Object clone() : It volition exercise in addition to provide shallow re-create of this hashtable.
• boolean contains(Object value) :It volition banking concern fit inwards Hashtable for whatever fundamental maps to the specified value.
• boolean containsKey(Object key) : It volition banking concern fit if whatever fundamental is available inwards Hashtable which is same every bit specified object.
• boolean containsValue(Object value) : It volition provide truthful if Hashtablehas whatever fundamental which maps to specified value.
• Enumeration<V> elements() : Returns an enumeration of the values inwards this Hashtable.
• Set<Map.Entry<K,V>> entrySet() : It volition provide laid upwards persuasion of Hashtable alongside mapping.
• boolean equals(Object o) : It volition banking concern fit in addition to compare given object alongside map for equality.
• V get(Object key) : It volition provide value which is mapped alongside specified fundamental inwards map. Return naught if no mapping found.
• int hashCode() : It volition provide has code value for this map.
• boolean isEmpty() : It volition banking concern fit if Hashtable is empty in addition to no mapping found.
• Enumeration<K> keys() : It volition returns an enumeration of the keys inwards this Hashtable.
• Set<K> keySet() : It volition provide laid upwards persuasion of keys contained inwards this map.
• V put(K key, V value) : Map in addition to insert specified fundamental alongside value inwards map.
• void putAll(Map<? extends K,? extends V> t) : It volition re-create all key-values mapping from specified map to this map.
• protected void rehash() : It volition increases the capacity of in addition to internally reorganizes this Hashtable, inwards social club to adapt in addition to access its entries to a greater extent than efficiently.
• V remove(Object key) : It volition take specified fundamental in addition to its mapped value from
• int size() : It volition provide size of Hashtable.
• Collection<V> values() : It volition provide collection persuasion of map.

I convey created sample illustration for Hashtable to demo usage of basic methods.

HashTableExample

package JAVAExamples;  import java.util.Hashtable; import java.util.Map;  world shape HashTableExample {   world static void main(String[] args) {   Hashtable<Integer, String> ht = novel Hashtable<Integer, String>();    ht.put(1000, "London");   ht.put(1001, "Mumbai");   ht.put(1002, "Chicago");   ht.put(1003, "Tokyo");   ht.put(1004, "Paris");   ht.put(1005, "Moscow");   ht.put(1006, "Berlin");    for (Map.Entry m : ht.entrySet()) {    System.out.println(m.getKey() + " " + m.getValue());   }      //Check if at that topographic point is whatever fundamental inwards map which maps to specified value.   System.out.println("Map has whatever fundamental for Chicago? : "+ht.contains("Chicago"));      //Check if specified fundamental is available inwards map.   System.out.println("Map has fundamental 1009? : "+ht.contains(1009));      //Get size of map   System.out.println("Map size is : "+ht.size());      }  }

Output :

1004 Paris 1003 Tokyo 1002 Chicago 1001 Bombay Map has whatever fundamental for Chicago? : truthful Map has fundamental 1009? : imitation Map size is : 7

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Selenium Tutorial : The Path To The Driver Executable Must Live On Ready Past Times The Webdriver.Gecko.Driver Organisation Property

Since end update of selenium 3, Most of the users(especially those who are novel amongst selenium) are facing mutual effect amongst fault "Exception inwards thread "main" java.lang.IllegalStateException: The path to the driver executable must move develop past times the webdriver.gecko.driver organisation property; for to a greater extent than information, encounter https://github.com/mozilla/geckodriver. The latest version tin lavatory move downloaded from https://github.com/mozilla/geckodriver/releases" when try to execute examination inwards firefox browser.

Configure Geckodriver In Selenium Test

This fault is bout downloading latest version of geckodriver exe in addition to configuring it amongst your selenium test. So, Lets encounter how to create it.

To resolve this issue,

• You convey to download latest version of geckodriver from HERE. 
• Download wi32 or win64 zippo file equally per your organisation configuration.

• Now extract the zippo file.
• You volition get geckodriver.exe from extracted folder.
• Now Put geckodriver.exe in you lot E: drive.
• Now you lot convey to render path of geckodriver.exe in your selenium examination using System.setProperty equally given inwards below given test.

import java.util.concurrent.TimeUnit; import org.openqa.selenium.WebDriver; import org.openqa.selenium.firefox.FirefoxDriver;   populace shape examination {   populace static void main(String[] args) {   //Set the path of geckodriver.exe.   System.setProperty("webdriver.gecko.driver","E:\\geckodriver.exe");     WebDriver driver = novel FirefoxDriver();     driver.manage().timeouts().implicitlyWait(15, TimeUnit.SECONDS);     driver.get("http://www.google.com");         driver.quit();  } }

That is it. Your examination volition run smoothly straightaway inwards firefox browser.