Create your own LinkedList - Java Data Structure

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Description

Create your own LinkedList

Demo Code



public class Main {
  public static void main(String[] args) {
    LinkedList linkedList = new LinkedList(); // creation of Linked List

    linkedList.insertFirst(11);//from  w w  w  .  j av a  2 s  .c om
    linkedList.insertFirst(21);
    linkedList.insertFirst(59);
    linkedList.insertFirst(14);
    linkedList.insertFirst(39);

    linkedList.displayLinkedList(); // display LinkedList

    System.out.print("Deleted Nodes: ");
    Node deletedNode = linkedList.deleteFirst(); // delete Node
    deletedNode.displayNode(); // display deleted Node.
    deletedNode = linkedList.deleteFirst(); // delete Node.
    deletedNode.displayNode(); // display deleted Node.

    System.out.println();// sysout used to format output
    linkedList.displayLinkedList(); // Again display LinkedList

  }

}

class Node {
  public int data;
  public Node next;

  public Node(int data) {
    this.data = data;
  }

  public void displayNode() {
    System.out.print(data + " ");
  }
}

class LinkedList {
  private Node first;

  public LinkedList() {
    first = null;
  }

  public void insertFirst(int data) {
    Node newNode = new Node(data); // Creation of New Node.
    newNode.next = first; // newLink ---> old first
    first = newNode; // first ---> newNode
  }

  /**
   * Deletes first Node of Singly LinkedList
   */
  public Node deleteFirst() {
    if (first == null) { // means LinkedList in empty, throw
                // exception.
      throw new LinkedListEmptyException("LinkedList doesn't contain any Nodes.");
    }
    Node tempNode = first; // save reference to first Node in
                // tempNode-
                // so that we could return saved
                // reference.
    first = first.next; // delete first Node (make first point to
              // second
              // node)
    return tempNode; // return tempNode (i.e. deleted Node)
  }

  /**
   * Display Singly LinkedList
   */
  public void displayLinkedList() {
    System.out.print("Displaying LinkedList [first--->last]: ");
    Node tempDisplay = first; // start at the beginning of
                  // linkedList
    while (tempDisplay != null) { // Executes until we don't find
                    // end of
                    // list.
      tempDisplay.displayNode();
      tempDisplay = tempDisplay.next; // move to next Node
    }
    System.out.println();

  }

  class LinkedListFullException extends RuntimeException {

    public LinkedListFullException() {
      super();
    }

    public LinkedListFullException(String message) {
      super(message);
    }

  }

  class LinkedListEmptyException extends RuntimeException {

    public LinkedListEmptyException() {
      super();
    }

    public LinkedListEmptyException(String message) {
      super(message);
    }

  }
}

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