Collections

I study a tutorial about JAVA and this was an example of it about collections.However when i try to call method sort,the system can not find it.Why?I have imported java.util.*

Code :

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package collections;
 
import java.util.*;//library
 
public class Collections {
 
    //Purpose:Create an ArrayList which stores strings
    public static void main(String[] args) {
        List<String> l = new ArrayList();
 
        String first="Hello";
 
        l.add(first);
        l.add(" world");
        l.add("JAVA");
 
        l.set(2,"JAVA2");//set modifies a value of the list
 
        Collections.sort(l);//sort the list
 
        System.out.println(l);
        System.out.println("Size of the list = " + l.size());
 
        int i = l.indexOf(" world");//will return the position of <world>
        System.out.println("String <world> is at " + i + " cell");
 
        l.remove("JAVA2");//will remove the first appearence of <JAVA2>
 
        l.clear();//removes all the elements of the list
        if(l.isEmpty()) 
            System.out.println("empty list");
        System.out.println(l);
    }
}

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The error occurs at this line Collections.sort(l);//sort the list

Your class's name is also Collections, try renaming your class and see what happens :)

Do not write classes with names that conflict with the java API - you've named your class Collections, and it does not have a method named sort. The java.util.Collections class does, however java will not be able to find it. Rename your class (recommended), or explicitly call the method you wish to call (java.util.Collections.sort(l))
Edit: too slow. elamre beat me to it.

Hmm..I see what happened.Thank you very much!