import java.util.*;

public class LinkedListDemo
{
    public static void main(String[] args)
    {
        LinkedList link=new LinkedList();
        link.add("a");
        link.add("b");
        link.add(new Integer(10));
        System.out.println("The contents of array is" + link);
        System.out.println("The size of an linkedlist is" + link.size());

        link.addFirst(new Integer(20));
        System.out.println("The contents of array is" + link);
        System.out.println("The size of an linkedlist is" + link.size());

        link.addLast("c");
        System.out.println("The contents of array is" + link);
        System.out.println("The size of an linkedlist is" + link.size());

        link.add(2,"j");
        System.out.println("The contents of array is" + link);
        System.out.println("The size of an linkedlist is" + link.size());

        link.add(1,"t");
        System.out.println("The contents of array is" + link);
        System.out.println("The size of an linkedlist is" + link.size());

        link.remove(3);
        System.out.println("The contents of array is" + link);
        System.out.println("The size of an linkedlist is" + link.size());
    }
}

this is the error i got..

--------------------Configuration: <Default>--------------------
Note: C:\Users\Fajutag\Documents\Java Saved Files\LinkedListDemo.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.

Process completed.

can someone tell me what should i do on this..

either ignore it, or don't use unchecked or unsafe operations ....
if you want more information about what the 'problem' (it's more a remark then a problem, but still) is: do as the message suggests and recompile with the
-Xlint:unchecked
argument.

but how do i compile with that Xlint:unchecked?..

its simple

currently you are compiling this way
javac <className.java>

You can add the option "-Xlint:unchecked" during compilation like below

javac -Xlint:unchecked <className.java>

But it is not necessary. You can ignore the message straight away

or you add that argument as compile argument in the ide you use.
but, as mentioned before, it is rather a remark. the application does compile and run.

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