A complete working Java program to demonstrate all insertion methods on linked list

package linked.list;

/**
*
* @author SHASHI
*/
// A complete working Java program to demonstrate all insertion methods
// on linked list
class LinkedList
{
Node head; // head of list

/* Linked list Node*/
class Node
{
int data;
Node next;
Node(int d) {data = d; next = null; }
}

/* Inserts a new Node at front of the list. */
public void push(int new_data)
{
/* 1 & 2: Allocate the Node &
Put in the data*/
Node new_node = new Node(new_data);

/* 3. Make next of new Node as head */
new_node.next = head;

/* 4. Move the head to point to new Node */
head = new_node;
}

/* Inserts a new node after the given prev_node. */
public void insertAfter(Node prev_node, int new_data)
{
/* 1. Check if the given Node is null */
if (prev_node == null)
{
System.out.println(“The given previous node cannot be null”);
return;
}

/* 2 & 3: Allocate the Node &
Put in the data*/
Node new_node = new Node(new_data);

/* 4. Make next of new Node as next of prev_node */
new_node.next = prev_node.next;

/* 5. make next of prev_node as new_node */
prev_node.next = new_node;
}

/* Appends a new node at the end. This method is 
defined inside LinkedList class shown above */
public void append(int new_data)
{
/* 1. Allocate the Node &
2. Put in the data
3. Set next as null */
Node new_node = new Node(new_data);

/* 4. If the Linked List is empty, then make the
new node as head */
if (head == null)
{
head = new Node(new_data);
return;
}

/* 4. This new node is going to be the last node, so
make next of it as null */
new_node.next = null;

/* 5. Else traverse till the last node */
Node last = head;
while (last.next != null)
last = last.next;

/* 6. Change the next of last node */
last.next = new_node;
return;
}

/* This function prints contents of linked list starting from
the given node */
public void printList()
{
Node tnode = head;
while (tnode != null)
{
System.out.print(tnode.data+” “);
tnode = tnode.next;
}
}

/* Driver program to test above functions. Ideally this function
should be in a separate user class. It is kept here to keep
code compact */
public static void main(String[] args)
{
/* Start with the empty list */
LinkedList llist = new LinkedList();

// Insert 6. So linked list becomes 6->NUllist
llist.append(6);

// Insert 7 at the beginning. So linked list becomes
// 7->6->NUllist
llist.push(7);

// Insert 1 at the beginning. So linked list becomes
// 1->7->6->NUllist
llist.push(1);

// Insert 4 at the end. So linked list becomes
// 1->7->6->4->NUllist
llist.append(4);

// Insert 8, after 7. So linked list becomes
// 1->7->8->6->4->NUllist
llist.insertAfter(llist.head.next, 8);

System.out.println(“\nCreated Linked list is: “);
llist.printList();
}
}

OUTPUT

Created Linked list is:
1 7 8 6 4