How to implement LinkedList data structure in Java?

1. Introduction

• Linked List is part of the Collection framework in the java.util package.

• The implementation of LinkedList data structure, which is a linear data structure in which elements are not stored in consecutive positions , and each element is a separate object, Has data part and address part.

• Elements are linked using pointers and addresses. Each element is called a node

2. Java linked list methods

Method	Description
add(int index, E element)	This method inserts the specified element at the specified position in this list.
add(E e)	This method appends the specified element to the end of this list.
addAll(int index, Collection c)	This method inserts all elements in the specified collection into this list, starting at the specified position.
addAll(Collection c)	This method appends all elements in the specified collection to the end of this list, in the order they are returned by the iterator of the specified collection .
addFirst(E e)	This method inserts the specified element at the beginning of this list.
addLast(E e)	This method appends the specified element to the end of this list.
clear()	This method removes all elements from this list.
clone()	This method returns a shallow copy of this LinkedList.
contains(Object o)	This method returns true if this list contains the specified element.
descendingIterator()	This method returns an iterator of the elements in this deque in reverse order.
element()	This method retrieves but does not remove the head (first element) of this list.
get(int index)	This method returns the element at the specified position in this list.
getFirst()	This method returns the first element in this list.
getLast()	This method returns the last element in this list.
indexOf(Object o)	This method returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element .
lastIndexOf(Object o)	This method returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element.
listIterator(int index)	This method returns a list iterator of the elements in this list (in appropriate order), starting at the specified position in the list.
offer(E e)	This method adds the specified element to the tail (last element) of this list.
offerFirst(E e)	This method inserts the specified element at the front of this list.
offerLast(E e)	This method inserts the specified element at the end of this list.
peek()	This method retrieves but does not remove the head (first element) of this list.
peekFirst()	This method retrieves but does not delete the first element of this list, or returns null if this list is empty.
peekLast()	This method retrieves but does not delete the last element of this list, or returns null if this list is empty.
poll()	This method retrieves and removes the head (first element) of this list.
pollFirst()	This method retrieves and removes the first element of this list, or returns null if this list is empty.
pollLast()	This method retrieves and removes the last element of this list, or returns null if this list is empty.
pop()	This method pops an element from the stack represented by this list.
push(E e)	This method pushes an element onto the stack represented by this list.
remove()	This method retrieves and removes the head (first element) of this list.
remove(int index)	This method removes the element at the specified position in this list.
remove(Object o)	This method removes the first occurrence of the specified element from this list, if it exists.
removeFirst()	This method removes and returns the first element from the list.
removeFirstOccurrence(Object o)	This method removes the first occurrence of the specified element in this list (when traversing the list from beginning to end).
removeLast()	This method removes and returns the last element from the list.
removeLastOccurrence(Object o)	This method removes the last occurrence of the specified element in this list (when the list is traversed from beginning to end).
set(int index, E element)	This method replaces the element at the specified position in this list with the specified element.
size()	This method returns the number of elements in this list.
spliterator()	This method creates a late-bound and fail-fast Spliterator on the elements in this list.
toArray()	This method returns an array containing all the elements in this list in correct order (from the first element to the last element).
toArray(T[] a)	This method returns an array containing this list in correct order (from first element to last element) all elements of the returned array; the runtime type of the returned array is the type of the specified array.
toString()	This method returns a string containing all the elements in this list in the correct order (from the first element to the last element) , each element is separated by commas, and the string is enclosed in square brackets.

3. Code

public class T1 {
    public static void main(String[] args) {
        LinkedList<String> ll = new LinkedList<String>();
        ll.add("B");
        ll.addLast("C");
        ll.addFirst("D");
        ll.add(2, "E");
        System.out.println(ll);
    }
}

 [D, B, E, C]

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