How do I implement a Linked List in Java?

Question

What's the best way to make a linked list in Java?

Answer 1

Java has a LinkedList implementation, that you might wanna check out. You can download the JDK and it's sources at java.sun.com.

Answer 2

That question is timely and hilarious. Thanks!

Answer 3

You should check your textbook and class notes.

Answer 4

I hope you don't get too many down votes for making a joke. I love the homework tag, nice touch.

Answer 5

I lol'd.

Answer 6

Oh I see, you were just pretending to be a 29 year old developer/users group founder in all those other questions, this is the real you. . . .right?

Answer 7

Vote down requires 100 reputation. :\

Answer 8

Use java.util.LinkedList. Like this:

list = new java.util.LinkedList()

Answer 9

You can just read the source code of how Java implements it, comes with every JDK.

Answer 10

Implement it in C.

Answer 11

I second the statement about using java's LinkedList class, but you could also man up and code your own from scratch.

Answer 12

The obvious solution to developers familiar to Java is to use the LinkedList class already provided in java.util. Say, however, you wanted to make your own implementation for some reason. Here is a quick example of a linked list that inserts a new link at the beginning of the list, deletes from the beginning of the list and loops through the list to print the links contained in it. Enhancements to this implementation include making it a double-linked list, adding methods to insert and delete from the middle or end, and by adding get and sort methods as well.

Note: In the example, the Link object doesn't actually contain another Link object - nextLink is actually only a reference to another link.

class Link {
    public int data1;
    public double data2;
    public Link nextLink;

    //Link constructor
    public Link(int d1, double d2) {
     data1 = d1;
     data2 = d2;
    }

    //Print Link data
    public void printLink() {
     System.out.print("{" + data1 + ", " + data2 + "} ");
    }
}

class LinkList {
    private Link first;

    //LinkList constructor
    public LinkList() {
     first = null;
    }

    //Returns true if list is empty
    public boolean isEmpty() {
     return first == null;
    }

    //Inserts a new Link at the first of the list
    public void insert(int d1, double d2) {
     Link link = new Link(d1, d2);
     link.nextLink = first;
     first = link;
    }

    //Deletes the link at the first of the list
    public Link delete() {
     Link temp = first;
     first = first.nextLink;
     return temp;
    }

    //Prints list data
    public void printList() {
     Link currentLink = first;
     System.out.print("List: ");
     while(currentLink != null) {
      currentLink.printLink();
      currentLink = currentLink.nextLink;
     }
     System.out.println("");
    }
}  

class LinkListTest {
    public static void main(String[] args) {
     LinkList list = new LinkList();

     list.insert(1, 1.01);
     list.insert(2, 2.02);
     list.insert(3, 3.03);
     list.insert(4, 4.04);
     list.insert(5, 5.05);

     list.printList();

     while(!list.isEmpty()) {
      Link deletedLink = list.delete();
      System.out.print("deleted: ");
      deletedLink.printLink();
      System.out.println("");
     }
     list.printList();
    }
}

Answer 13

Its much better to use java.util.LinkedList, because it's probably much more optimized, than the one that you will write.

Answer 14

this linked list creation is right that program create a linked list with out using linkedclass. by dev dixit

Answer 15

ur code is not thread safe..

Answer 16

The above linked list display in opposite direction. I think the correct implementation of insert method should be

public void insert(int d1, double d2) { 
    Link link = new Link(d1, d2); 

    if(first==null){
        link.nextLink = null;
        first = link; 
        last=link;
    }
    else{
        last.nextLink=link;
        link.nextLink=null;
        last=link;
    }
} 

Answer 17

The delete function has a memory leak! The variable first should be set to NULL!