How does adding a new node in the middle of a linked list occur?

To add a new node in the middle of a linked list in Java, you need to:

1. Create a new node with the desired value.
2. Find the node after which you want to insert the new node (for example, by traversing the list).
3. Set the new node's next reference to the next node of the found node.
4. Change the found node's next reference to point to the new node.

Example for a singly linked list:

class Node {
    int data;
    Node next;

    Node(int data) {
        this.data = data;
        this.next = null;
    }
}

// Insert a new node after prevNode
void insertAfter(Node prevNode, int newData) {
    if (prevNode == null) {
        System.out.println("Previous node cannot be null");
        return;
    }
    Node newNode = new Node(newData);
    newNode.next = prevNode.next;
    prevNode.next = newNode;
}

Thus, the new node ends up between prevNode and the next node.