Java ArrayDeque (ar piemēriem)

Šajā apmācībā mēs ar piemēru palīdzību uzzināsim par ArrayDeque klasi un tās metodēm. Mēs arī iemācīsimies izmantot masīva deque, lai ieviestu kaudzi.

Java valodā mēs varam izmantot ArrayDequeklasi, lai ieviestu rindas un samazinātu datu struktūras, izmantojot masīvus.

ArrayDeque ieviestās saskarnes

ArrayDequeKlases īsteno šos divus saskarnes:

  • Java rindas saskarne
  • Java Deque saskarne

ArrayDeque izveide

Lai izveidotu masīva deque, mums ir jāimportē java.util.ArrayDequepakete.

Lūk, kā mēs varam izveidot masīva deque Java:

 ArrayDeque animal = new ArrayDeque();

Šeit tips norāda masīva deque veidu. Piemēram,

 // Creating String type ArrayDeque ArrayDeque animals = new ArrayDeque(); // Creating Integer type ArrayDeque ArrayDeque age = new ArrayDeque();

ArrayDeque metodes

ArrayDequeKlase nodrošina realizācijas visiem metožu, kas atrodas Queueun Dequeinterfeisu.

Ievietojiet elementus Deque

1. Pievienojiet elementus, izmantojot add (), addFirst () un addLast ()

  • add() - ievieto norādīto elementu masīva deque beigās
  • addFirst() - ievieto norādīto elementu masīva deque sākumā
  • addLast()- ievieto norādīto masīva deque beigās (ekvivalents add())

Piezīme: Ja masīvs deque ir pilna, visas šīs metodes add(), addFirst()un addLast()met IllegalStateException.

Piemēram,

 import java.util.ArrayDeque; class Main ( public static void main(String() args) ( ArrayDeque animals= new ArrayDeque(); // Using add() animals.add("Dog"); // Using addFirst() animals.addFirst("Cat"); // Using addLast() animals.addLast("Horse"); System.out.println("ArrayDeque: " + animals); ) )

Rezultāts

 ArrayDeque: (kaķis, suns, zirgs)

2. Ievietojiet elementus, izmantojot piedāvājumu (), offerFirst () un offerLast ()

  • offer() - ievieto norādīto elementu masīva deque beigās
  • offerFirst() - ievieto norādīto elementu masīva deque sākumā
  • offerLast() - ievieto norādīto elementu masīva deque beigās

Piezīme: offer() , offerFirst()un offerLast()atgriež trueja veiksmīgi ievietota elements; ja masīva deque ir pilns, šīs metodes atgriežas false.

Piemēram,

 import java.util.ArrayDeque; class Main ( public static void main(String() args) ( ArrayDeque animals= new ArrayDeque(); // Using offer() animals.offer("Dog"); // Using offerFirst() animals.offerFirst("Cat"); // Using offerLast() animals.offerLast("Horse"); System.out.println("ArrayDeque: " + animals); ) )

Rezultāts

 ArrayDeque: (kaķis, suns, zirgs)

Piezīme: Ja masīva dekode ir pilna

  • add()metode mest izņēmums
  • ka offer()metode atgriežfalse

Piekļuve ArrayDeque elementiem

1. Piekļuves elementi, izmantojot getFirst () un getLast ()

  • getFirst() - atgriež masīva deque pirmo elementu
  • getLast() - atgriež masīva deque pēdējo elementu

Piezīme: Ja masīva deque ir tukšs, getFirst()un getLast()met NoSuchElementException.

Piemēram,

 import java.util.ArrayDeque; class Main ( public static void main(String() args) ( ArrayDeque animals= new ArrayDeque(); animals.add("Dog"); animals.add("Cat"); animals.add("Horse"); System.out.println("ArrayDeque: " + animals); // Get the first element String firstElement = animals.getFirst(); System.out.println("First Element: " + firstElement); // Get the last element String lastElement = animals.getLast(); System.out.println("Last Element: " + lastElement); ) )

Rezultāts

 ArrayDeque: (suns, kaķis, zirgs) pirmais elements: suns pēdējais elements: zirgs

2. Piekļūstiet elementiem, izmantojot peek (), peekFirst () un peekLast () metodi

  • peek() - atgriež masīva deque pirmo elementu
  • peekFirst()- atgriež masīva deque pirmo elementu (ekvivalents peek())
  • peekLast() - atgriež masīva deque pēdējo elementu

Piemēram,

 import java.util.ArrayDeque; class Main ( public static void main(String() args) ( ArrayDeque animals= new ArrayDeque(); animals.add("Dog"); animals.add("Cat"); animals.add("Horse"); System.out.println("ArrayDeque: " + animals); // Using peek() String element = animals.peek(); System.out.println("Head Element: " + element); // Using peekFirst() String firstElement = animals.peekFirst(); System.out.println("First Element: " + firstElement); // Using peekLast String lastElement = animals.peekLast(); System.out.println("Last Element: " + lastElement); ) )

Rezultāts

 ArrayDeque: (suns, kaķis, zirgs) galvas elements: suns pirmais elements: suns pēdējais elements: zirgs

Piezīme: Ja masīva dekode ir tukša peek(),, peekFirst()un getLast()met NoSuchElementException.

Noņemiet ArrayDeque elementus

1. Noņemiet elementus, izmantojot metodi remove (), removeFirst (), removeLast ()

  • remove() - atgriež un noņem elementu no masīva deque pirmā elementa
  • remove(element) - atgriež un noņem norādīto elementu no masīva deque galvas
  • removeFirst()- atgriež un noņem masīva deque pirmo elementu (ekvivalents remove())
  • removeLast() - atgriež un noņem masīva deque pēdējo elementu

Note: If the array deque is empty, remove(), removeFirst() and removeLast() method throws an exception. Also, remove(element) throws an exception if the element is not found.

For example,

 import java.util.ArrayDeque; class Main ( public static void main(String() args) ( ArrayDeque animals= new ArrayDeque(); animals.add("Dog"); animals.add("Cat"); animals.add("Cow"); animals.add("Horse"); System.out.println("ArrayDeque: " + animals); // Using remove() String element = animals.remove(); System.out.println("Removed Element: " + element); System.out.println("New ArrayDeque: " + animals); // Using removeFirst() String firstElement = animals.removeFirst(); System.out.println("Removed First Element: " + firstElement); // Using removeLast() String lastElement = animals.removeLast(); System.out.println("Removed Last Element: " + lastElement); ) )

Output

 ArrayDeque: (Dog, Cat, Cow, Horse) Removed Element: Dog New ArrayDeque: (Cat, Cow, Horse) Removed First Element: Cat Removed Last Element: Horse

2. Remove elements using the poll(), pollFirst() and pollLast() method

  • poll() - returns and removes the first element of the array deque
  • pollFirst() - returns and removes the first element of the array deque (equivalent to poll())
  • pollLast() - returns and removes the last element of the array deque

Note: If the array deque is empty, poll(), pollFirst() and pollLast() returns null if the element is not found.

For example,

 import java.util.ArrayDeque; class Main ( public static void main(String() args) ( ArrayDeque animals= new ArrayDeque(); animals.add("Dog"); animals.add("Cat"); animals.add("Cow"); animals.add("Horse"); System.out.println("ArrayDeque: " + animals); // Using poll() String element = animals.poll(); System.out.println("Removed Element: " + element); System.out.println("New ArrayDeque: " + animals); // Using pollFirst() String firstElement = animals.pollFirst(); System.out.println("Removed First Element: " + firstElement); // Using pollLast() String lastElement = animals.pollLast(); System.out.println("Removed Last Element: " + lastElement); ) )

Output

 ArrayDeque: (Dog, Cat, Cow, Horse) Removed Element: Dog New ArrayDeque: (Cat, Cow, Horse) Removed First Element: Cat Removed Last Element: Horse

3. Remove Element: using the clear() method

To remove all the elements from the array deque, we use the clear() method. For example,

 import java.util.ArrayDeque; class Main ( public static void main(String() args) ( ArrayDeque animals= new ArrayDeque(); animals.add("Dog"); animals.add("Cat"); animals.add("Horse"); System.out.println("ArrayDeque: " + animals); // Using clear() animals.clear(); System.out.println("New ArrayDeque: " + animals); ) )

Output

 ArrayDeque: (Dog, Cat, Horse) New ArrayDeque: ()

Iterating the ArrayDeque

  • iterator() - returns an iterator that can be used to iterate over the array deque
  • descendingIterator() - returns an iterator that can be used to iterate over the array deque in reverse order

In order to use these methods, we must import the java.util.Iterator package. For example,

 import java.util.ArrayDeque; import java.util.Iterator; class Main ( public static void main(String() args) ( ArrayDeque animals= new ArrayDeque(); animals.add("Dog"); animals.add("Cat"); animals.add("Horse"); System.out.print("ArrayDeque: "); // Using iterator() Iterator iterate = animals.iterator(); while(iterate.hasNext()) ( System.out.print(iterate.next()); System.out.print(", "); ) System.out.print("ArrayDeque in reverse order: "); // Using descendingIterator() Iterator desIterate = animals.descendingIterator(); while(desIterate.hasNext()) ( System.out.print(desIterate.next()); System.out.print(", "); ) ) )

Output

 ArrayDeque: (Dog, Cat, Horse) ArrayDeque in reverse order: (Horse, Cat, Dog)

Other Methods

Methods Descriptions
element() Returns an element from the head of the array deque.
contains(element) Searches the array deque for the specified element.
If the element is found, it returns true, if not it returns false.
size() Returns the length of the array deque.
toArray() Converts array deque to array and returns it.
clone() Creates a copy of the array deque and returns it.

ArrayDeque as a Stack

To implement a LIFO (Last-In-First-Out) stacks in Java, it is recommended to use a deque over the Stack class. The ArrayDeque class is likely to be faster than the Stack class.

ArrayDeque provides the following methods that can be used for implementing a stack.

  • push() - adds an element to the top of the stack
  • peek() - returns an element from the top of the stack
  • pop() - returns and removes an element from the top of the stack

For example,

 import java.util.ArrayDeque; class Main ( public static void main(String() args) ( ArrayDeque stack = new ArrayDeque(); // Add elements to stack stack.push("Dog"); stack.push("Cat"); stack.push("Horse"); System.out.println("Stack: " + stack); // Access element from top of stack String element = stack.peek(); System.out.println("Accessed Element: " + element); // Remove elements from top of stack String remElement = stack.pop(); System.out.println("Removed element: " + remElement); ) )

Output

 Stack: (Horse, Cat, Dog) Accessed Element: Horse Removed Element: Horse

ArrayDeque Vs. LinkedList Class

Both ArrayDeque and Java LinkedList implements the Deque interface. However, there exist some differences between them.

  • LinkedList supports null elements, whereas ArrayDeque doesn't.
  • Katrā sasaistītā saraksta mezglā ir saites uz citiem mezgliem. Tāpēc ir LinkedListnepieciešams vairāk krātuves nekā ArrayDeque.
  • Ja jūs ieviešat rindu vai deque datu struktūru, ArrayDequevisticamāk , ka an ātrāka par a LinkedList.

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