How to retrieve data from linked list java

Question

Hi, I am trying create a linked list to store some data. How can I retrieve the actual data from the list values and not the item's object reference.

public class myList()
{
    private LinkedList<Node> list = null;

    public myList()
    {
        list = new LinkedList<Node>();
    }

    public void addX(Node x)
    {
       list.add(x)
    }

    public void print()
    {
        for(int i = 0; i<list.size(); i++)
        {
            System.out.println(list.get(i));
        }

     }
}

public class Node
{
    private String x;
    private int y;
    private int z;

    public Node(String x, int y, int z)
    {
        this.x = x;
        this.y = y;
        this.z = z;
    }
}

public static void main (String[] args)
{
    myList.addX(new Node(x,1,2));
    myList.print();
}

When I run this it prints the memory address/reference instead of the actual values. What am I doing wrong? Example output: Node@838378c7

Any help is appreciated.

Thanks.

Your code has numerous errors. It does not compile. Post valid code. — Susam Pal, Apr 10 '14 at 11:39

score 3 · Answer 1 · answered Apr 10 '14 at 11:39

3

toString() method in Object is

public String toString() {
return getClass().getName() + "@" + Integer.toHexString(hashCode());
}

which is exactly what will get printed. You need to override it in Node class to show your output of toString().

answered Apr 10 '14 at 11:39

Aniket Thakur

66,731
38
279
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score 0 · Answer 2 · edited May 23 '17 at 10:33

0

The output you see is generated by the default toString()-method, to get an output format of your choice you need to override the toString()-method.

For more information see this question

edited May 23 '17 at 10:33

Community

1
1

answered Apr 10 '14 at 11:37

LionC

3,106
1
22
31

score 0 · Answer 3 · answered Apr 10 '14 at 11:40

You are printing the Node class object which does not have a toString() method, and so it uses the the toString() of the Object class which prints the output that you see.

Override to toString() method and print the content in the the way you want in that method so that the output when when printing a Node object is as you expect it to be

score 0 · Accepted Answer · answered Apr 10 '14 at 11:41

Override the toString method on the Node class:

public class Node
{
    private String x;
    private int y;
    private int z;

    public Node(String x, int y, int z)
    {
        this.x = x;
        this.y = y;
        this.z = z;
    }

    @Override
    public String toString() {
        return x + "/" + y + "/" + z;
    }
}

This example returns the x, y and z values with a "/" seperator between each. However, you can obviously change the return value of the toString method to suit how you would like your data displayed.

This tutorial explains the concept quite well.

How to retrieve data from linked list java

4 Answers4