💦 😲 📍 Java: passing parameters by value or by reference ✌🏽 🤦 🚢

A simple explanation of the principles of parameter passing in Java.

Many programmers often confuse which parameters in Java are passed by value and which by reference. Let's visualize this process, and then you will see how simple everything is.

Let's start with the basics.

Data is passed between methods via parameters. There are two ways to pass parameters:

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class Node {
   int data;
   Node next;
   Node(int d){
       data = d;
       next = null;
   }
}
class LinkedList {
   public static Node push(Node head, int data) {
       Node newNode = new Node(data);
       newNode.next = head;
       head = newNode;
       return head;
   }
   public static void deleteNode(Node head, int position) {
  
       // List is empty
       if (head == null){
           return;
       }

      // If position is 1st, removing head node
      if (position == 1) {
          head = head.next;
          return;
      }
      Node prevNode = head;
      int i = 2;
      while (prevNode != null && i != position) {
          prevNode = prevNode.next;
          i++;
      }
     // When position is more than number of node
     if (prevNode == null || prevNode.next == null) {
         return;
     }
     prevNode.next = prevNode.next.next;
   }
   public static void printList(Node head) {
       Node currNode = head;
       while (currNode != null) {
           System.out.print(currNode.data + " ");
           currNode = currNode.next;
       }
   }
   public static void main(String[] args) {
       Node head = null;
       head = push(head, 5);
       head = push(head, 4);
       head = push(head, 3);
       head = push(head, 2);
       head = push(head, 1);
       System.out.println("Created Linked list is: ");
       printList(head);

       // Delete node at position 2
       deleteNode(head, 2);

       System.out.println("\nLinked List after Deletion at position 2: ");
       printList(head);
   }
}

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Removing the first node of a singly linked list

public static Node deleteNode(Node head, int position) {
   // List is empty
   if (head == null){
      return head;
   }

   // If position is 1st, removing head node
   if (position == 1) {
       head = head.next;
       return head;
   }
   Node prevNode = head;
   int i = 2;
   while (prevNode != null && i != position) {
       prevNode = prevNode.next;
       i++;
   }
   // When position is more than number of node
   if (prevNode == null || prevNode.next == null) {
       return head;
   }
   prevNode.next = prevNode.next.next;
   return head;
}
public static void main(String[] args) {
   Node head = null;
   head = push(head, 5);
   head = push(head, 4);
   head = push(head, 3);
   head = push(head, 2);
   head = push(head, 1);
   System.out.println("Created Linked list is: ");
   printList(head);

   // Delete node at position 2
   head = deleteNode(head, 2);

   System.out.println("\nLinked List after Deletion at position 2: ");
   printList(head);
}
//Rest of the code remains same

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Java: passing parameters by value or by reference

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