Retrieving elements from a link list

[titan5]

I need to create a list which contains objects of a particular class. I am having problem in retrieving the objects back from the list.
Here is my code for insertion into list-

import java.util.LinkedList;
import java.util.ListIterator;

public class listchek {

    int i;
    String name;

    public listchek(int k, String n)
    {
        i=k;
        name=n;
    }
        static LinkedList<listchek> list;

    public static void add(listchek lc)
    {
        list.add(lc);
    }

    public static void getlistelements()
    {


    }

}

 class insert
{
    public static void main(String arg[])
    {
        listchek ob1=new listchek(1, "first");
        listchek ob2=new listchek(2, "sec");
        listchek ob3=new listchek(3, "third");
        listchek ob4=new listchek(4, "fourth");

        listchek.add(ob1);
        listchek.add(ob2);
        listchek.add(ob3);
        listchek.add(ob4);


    }
}

How do i get the object values back from list?

[cale.macdonald]

Look @ the get method inside linked list

[titan5]

Look @ the get method inside linked list

Tried that.

List has elements of type listchek (class). I want to store it in a variable V.
If I am not wrong i think I can access the further class variables by V.i and V.name.

What should be the type of V? I tried creating - listchek V; but its giving an error.

N I was trying to use the listIterator method also so that I can get all the elements one by one.

[NormR1]

Comment on your variable name: V
Coding conventions for variables say they start with a lowercase letter.
Single letter names are not selfdocumenting as far as what the variable is used for. Use a name what when read shows what the variable contains or what it is used for.
The exceptions are for loop control variables: i,j,k

What should be the type of V? I tried creating - listchek V; but its giving an error.

When you get an error, please copy and paste the full text here.

[cale.macdonald]

Edit: What Norm said

[titan5]

Comment on your variable name: V
Coding conventions for variables say they start with a lowercase letter.
Single letter names are not selfdocumenting as far as what the variable is used for. Use a name what when read shows what the variable contains or what it is used for.
The exceptions are for loop control variables: i,j,k

Oh oh I was just giving an example that suppose if I use a variable V to get the list objects!!!
I just wanted to know its tyoe that I should use...

When you get an error, please copy and paste the full text here.

Ok here's my function-

public static void getlistelements()
	{
		listchek element;
		
		element=list.listIterator(0);  //Error : Type mismatch: cannot convert from ListIterator<listchek> to listchek
		
	}

What I want to do is I want to access the 4 objects which I have entered added in the list.

[NormR1]

Type mismatch: cannot convert from ListIterator<listchek> to listchek

The error message says it all. The variable element is of type: listchek.
The listIterator does NOT return an object of that type. You need to read the API doc for the listIterator method and see what type it returns.

[titan5]

The error message says it all. The variable element is of type: listchek.
The listIterator does NOT return an object of that type. You need to read the API doc for the listIterator method and see what type it returns.

Okk I managed to correct this a bit.

mport java.util.LinkedList;
import java.util.ListIterator;

public class listchek {
	
	int i;
	String name;
	
	public listchek(int k, String n)
	{
		i=k;
		name=n;
	}
		static LinkedList<listchek> list;
	
	public static void add(listchek lc)
	{
		list.add(lc);
	}

	public static void printlist()
	{
		ListIterator<listchek> element;
		
		element=list.listIterator(0);  
		
	}
	

}

public class Insert {

	public static void main(String arg[])
	{
		listchek ob1=new listchek(1, "first");
		listchek ob2=new listchek(2, "sec");
		listchek ob3=new listchek(3, "third");
		listchek ob4=new listchek(4, "fourth");
		
		listchek.add(ob1);
		listchek.add(ob2);
		listchek.add(ob3);
		listchek.add(ob4);
		
			
	}
}

When I run this code I get error in line 18 and 41 above. -
Exception in thread "main" java.lang.NullPointerException
at Test.listchek.add(listchek.java:21)
at Test.Insert.main(Insert.java:12)

M not getting the reason behind it :(

[NormR1]

The reason for a NPE is because you have not given a value to a variable and the variable is null.
To prevent getting a NPE, either assign a value to the variable
or test if the variable is null before trying to use it.

Where do you give "list" a value? You need something like:
list = A_VALID_VALUE_FOR_LIST;

[titan5]

The reason for a NPE is because you have not given a value to a variable and the variable is null.
To prevent getting a NPE, either assign a value to the variable
or test if the variable is null before trying to use it.

Where do you give "list" a value? You need something like:
list = A_VALID_VALUE_FOR_LIST;

The list which I have created should store objects of listchek.

I have created different objects of listchek and given them values. The I am passing it to list to be added.
I think the values are being passed to the object's variables int and String. How do I give values to the object then to store them in the list?

[NormR1]

How do I give values to the object

Use the class's constructor to give values to the object.
Or use settor methods to give values to a class object to save

store them in the list?

Use a method to add the objects to the list

[titan5]

Use the class's constructor to give values to the object.
Or use settor methods to give values to a class object to save

Use a method to add the objects to the list

Tats what I have done!! i am passing the values to the object through listchek constructor only..

N I have defined a separate method to add it to the list!

[NormR1]

Please P the C showing what U have D.

[titan5]

Please P the C showing what U have D.

I have already posted the code..
N I have solved the problem myself. The was a problem in the linkedlist declaration.

Neways thnx:)

[NormR1]

G L