Java - Delete the first node of the Linked List

In this method, the first node of the linked list is deleted. For example - if the given list is 10->20->30->40 and the first node is deleted, the list becomes 20->30->40.

Deleting the first node of the Linked List is very easy. If the head is not null then create a temp node pointing to head and move head to the next of head. Then delete the temp node.

The function pop_front is created for this purpose. It is a 3-step process.

void pop_front() {
  if(this.head != null) {
    
    //1. if head is not null, create a
    //   temp node pointing to head
    Node temp = this.head;
    
    //2. move head to next of head
    this.head = this.head.next;
    
    //3. delete temp node
    temp = null;  
  }
}

The below is a complete program that uses above discussed concept of deleting the first node of the linked list.

//node structure
class Node {
    int data;
    Node next;
};

class LinkedList {
  Node head;

  LinkedList(){
    head = null;
  }

  //Add new element at the end of the list
  void push_back(int newElement) {
    Node newNode = new Node();
    newNode.data = newElement;
    newNode.next = null; 
    if(head == null) {
      head = newNode;
    } else {
      Node temp = new Node();
      temp = head;
      while(temp.next != null)
        temp = temp.next;
      temp.next = newNode;
    }    
  }

  //Delete first node of the list
  void pop_front() {
    if(this.head != null) {
      Node temp = this.head;
      this.head = this.head.next;
      temp = null;  
    }
  }

  //display the content of the list
  void PrintList() {
    Node temp = new Node();
    temp = this.head;
    if(temp != null) {
      System.out.print("The list contains: ");
      while(temp != null) {
        System.out.print(temp.data + " ");
        temp = temp.next;
      }
      System.out.println();
    } else {
      System.out.println("The list is empty.");
    }
  }    
};

// test the code
public class Implementation { 
  public static void main(String[] args) {
    LinkedList MyList = new LinkedList();

    //Add four elements in the list.
    MyList.push_back(10);
    MyList.push_back(20);
    MyList.push_back(30);
    MyList.push_back(40);
    MyList.PrintList(); 

    //Delete the first node
    MyList.pop_front();
    MyList.PrintList();  
  }
}

The above code will give the following output:

The list contains: 10 20 30 40
The list contains: 20 30 40