Implement linked list in java

[Nilesh Srivastava]

Hi,

Can anyone tell me how to implement linked list in java without using JAVA API's.

Regards

[Neeraj Dheer]

hi Nilesh! you want the entire code?? i am sure you dont want the entire code, only a starting point, right?

since you know linked lists, i will not talk on that. the key concept while implementing linked lists in Java is that objects are always passed by reference.

here is a sample implementation. this is bare bones implementation, but i think sufficient to get you started.

class Info
{
 
//all info goes here

}
 
class Node
{
 
Info info;

Node nextNode;

Node addNode(Info zInfo)
{

info = zInfo;

nextNode = null;


//return this node that we just created
return this;

}

//method to set the next node in the list
void setNextNode(Node zNode)
{

node = zNode;

}

node getnextnode()
{

return node;

}

}

//all linked list related functionality(traversal, addition of a node, deletion of a node etc) here...
class LinkedList
{
 
Node firstNode;

void addNodeInTheEnd(Info zInfo)
{

//if list is empty

if(firstNode == null)
{

firstNode = addNode(new Info());// create Info object with the info and pass

return;

}

//list exists. add in the end

Node currentNode = firstnode;

//traverse till end of list and add node in the end
while(currentNode.getNextNode != null)
{

currentNode = currentNode.getNextNode();

}

currentNode.setNextNode(addNode(new Info());

}

}

[Adam Vinueza]

Neeraj outlined the basic idea, but here are a couple of details you might keep in mind.

1) Java's garbage collection features make removing a Node from a linked list easier, as you don't have to explicitly set a pointer to a Node to null.

2) When implementing a remove(Object key) method for your own linked list, you'll start to appreciate why Java included Iterator interfaces. You might want to implement your own iterator() function in your linked list that returns a special implementation of Iterator to remove Nodes in your linked list. That will make your code more readable and more OO.