# Java program to find middle of a linked list

## How to find middle of a linked list?

In here we are learning about a Java program to find the middle of a linked list. To find a middle of a linked , before that we should know that the number of link nodes are even or odd . If it’s odd then we have to take two pointer’s p1 and p2 as shown in the diagram p1 will move forward by one node and p2 will move forward two nodes. When p2 reaches the end of a linked list at that time p1 will be at the middle node of the linked list. ## Insertion in the middle of linked list in Java

Java program to find the middle of a linked list, (even case) When given number of link nodes are even we will follow the same fashion ad we are doing in odd case but over here we will divide the number of link nodes by 2 so as to get the middle node of a linked list

### Example:

input: 1–>2–>3–>4–>5

output

3

The middle of a given linked list is 3 ## Algorithm.

Step 1– Start

Step 2– Initialize a class

Step 3– Give input

Step 4– Node constructor

Step 6– Add a function to find the size of a linked list. // return this.size

Step 7 – Check whether the linked list is empty or not // return this.size () == 0

Step 8– run a loop for traversing the pointer and then print the linked list

Step 9– Add a node in the beginning.

Step 10– Create a temp node which points towards the head

Step 11– Linked list is empty, then head and tail both is temp

Step 12– add a function for finding the mid node.

Step 13– Take two pointers p1 and p2

Step 14– Move p1 by one node and p2 by two nodes

Step 15– When p2 reaches the end of a linked list, p1 will point to the middle node.

Step 16– End.

## Java Program to find middle of a Linked List

Run
```import java.lang.*;

{
// not using parameterized constructor would by default
// force head instance to become null
// Node head = null;  // can also do this, but not required

// Node Class
class Node
{
int data;
Node next;

Node (int x)		// parameterized constructor
{
data = x;
next = null;
}
}
public Node insert (int data)
{
// Creating newNode memory & assigning data value
Node newNode = new Node (data);
// assigning this newNode's next as current head node

// re-assigning head to this newNode

}

public void display ()
{
//as linked list will end when Node reaches Null
while (node != null)
{
System.out.print (node.data + " ");
node = node.next;
}
System.out.println ();
}

public int mid ()
{
return this.midNode ().data;
}

//Function to find the mid node
private Node midNode ()
{

//Take two pointers p1 and p2

//Move p1 by one node and p2 by two nodes
while (p2.next != null && p2.next.next != null)
{
p1 = p1.next;
p2 = p2.next.next;
}

//When p2 reaches the end, p1 will point to the mid node
return p1;

}

}

class Main
{
public static void main (String args[])
{

ll.insert (6);
ll.insert (5);
ll.insert (3);
ll.insert (4);
ll.insert (2);

ll.display ();

System.out.println ("Middle of the linked list is :- ");
System.out.println (ll.mid ());

}
}
```
```Output:

2 4 3 5 6
Middle of the linked list is :-
3
```

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