Fetch elements from LinkedList


There are several methods given in the linked list to retrieve the inserted elements. Each method has its own importance.
E.g. If user wants to retieve the first element from the list, it can choose among get(int index), getFirst(), element(), peek() or peekFirst() methods but there usages are different like get(int index) method provides the element from any given position(index) whereas getFirst(), element(), peek() or peekFirst() methods returns only first element from the list.

Let us see the different usages of these methods:

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package net.raj.test.list;

import java.util.LinkedList;

/**
 * @author Raj Saxena
 *
 */
public class LinkedListRetrieveImpl {
 public static void main(String... args) {
  // Declare an LinkedList
  LinkedList<String> list = new LinkedList<>();

  list.add("one");
  list.add("two");
  list.add("three");
  list.add("four");
  list.add("five");

  System.out.println("Original LinkedList :: " + list.toString());
  
  // Get an element from specified index
  System.out.println("Element at position 3 :: " + list.get(3));

  // Get the first element in this list
  System.out.println("First Element :: " + list.getFirst());
  
  // Retrieves, but does not remove, the head (first element) of this list
  System.out.println("Head Element  :: " + list.element() + " and Current LinkedList :: " + list.toString());
  
  // Retrieves, but does not remove, the head (first element) of this list
  System.out.println("Peek Element  :: " + list.peek() + " and Current LinkedList :: " + list.toString());
  
  // Retrieves, but does not remove, the first element of this list, or returns null if this list is empty
  System.out.println("Peek First Element :: " + list.peekFirst() + " and Current LinkedList :: " + list.toString());
  
  // Retrieves, but does not remove, the last element of this list, or returns null if this list is empty
  System.out.println("Peek Last Element :: " + list.peekLast() + " and Current LinkedList :: " + list.toString());
  
  // Retrieves and removes the head (first element) of this list
  System.out.println("Poll Element :: " + list.poll() + " and Modified LinkedList :: " + list.toString());
  
  // Retrieves and removes the first element of this list, or returns null if this list is empty
  System.out.println("Poll First Element :: " + list.pollFirst() + " and Modified LinkedList :: " + list.toString());
  
  // Retrieves and removes the last element of this list, or returns null if this list is empty
  System.out.println("Poll Last Element :: " + list.pollLast() + " and Modified LinkedList :: " + list.toString());
  
  // Get the last element in this list
  System.out.println("Last Element :: " + list.getLast() + " and Modified LinkedList :: " + list.toString());  
  
 }
}


Output:
Original LinkedList :: [one, two, three, four, five]
Element at position 3 :: four
First Element :: one
Head Element  :: one and Modified LinkedList :: [one, two, three, four, five]
Peek Element  :: one and Modified LinkedList :: [one, two, three, four, five]
Peek First Element :: one and Modified LinkedList :: [one, two, three, four, five]
Peek Last Element :: five and Modified LinkedList :: [one, two, three, four, five]
Poll Element :: one and Modified LinkedList :: [two, three, four, five]
Poll First Element :: two and Modified LinkedList :: [three, four, five]
Poll Last Element :: five and Modified LinkedList :: [three, four]
Last Element :: four and Modified LinkedList :: [three, four]

Look at my other posts:
Stack in Java
Custom Stack Implementation
Set Interface in Java
Custom Doubly LinkedList Implementation
Custom LinkedList Implementation
How to fetch elements from LinkedList
List Traversal
How to insert elements in List
How to remove element from list
How to declare Linked List and Implement
LinkedList Traversal In Reverse Sequential Order
ArrayList in Java
How to declare array list in java

Some other interesting blogs:
IOT and Big Data Technologies
Sustainability Cloud

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