unmodifiableList(List list)

[saikrishna cinux]

i am using Linkedlist in my program and i want to make it unmodifiable thru out my program so i am using this method


LinkedList<Object> l=new LinkedList<Objectl.add("a");
l.add("b");
l.add("c");
l.add("d");
List list=Collections.unmodifiableList(l);//here is an error

while i use arraylist,vector in place of linkedlist it is not showing any error

why?
linkedlist is also implementing the List interface as arraylist and vector does


:roll:


please somebody give me the best suggestion with example( iam learning OOPs through collection frame work)

[Jaikiran Pai]

Whats the exception that you are getting. The following program works using LinkedList:

package org.myapp;
 
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
 
public class Test {
 
/**
 * @param args
 */
public static void main(String[] args) {
LinkedList<Object> l = new LinkedList<Object>();
l.add("a");
l.add("b");
l.add("c");
l.add("d");
List list=Collections.unmodifiableList(l);
System.out.println("Size: " + list.size());
}
 
}

[Edwin Dalorzo]

I run your code and there are no errors in it.

What errors do you receive? Compile time? Run time?

LinkedList<Object> l=new LinkedList<Object>();
l.add("a");
l.add("b");
l.add("c");
l.add("d");
List list=Collections.unmodifiableList(l);//there is no error here

[Tony Morris]

You are likely receiving a compile-time warning.
List list=Collections.unmodifiableList(l);//here is an error
Try this:
List<Object> list=Collections.unmodifiableList(l);//here is an error

As a side note, I strongly recommend against using collections in this way (or even at all).