How to understand the compilation error of rewriting the base class method?

try to change the sort (), method of LinkedList, which originally implements interface list, but always reports an error. Please point out:

import java.util.*;
public class TestSort {

    
LinkedList mtn = new LinkedList();//

public static void main(String[] args){
        new TestSort().go();
}
    public void go(){
        //
        mtn.add("L1");
        mtn.add("E2");
        mtn.add("M3");
        mtn.add("C4");
        
        Compare_str nc = new Compare_str();//
        
        /*:*/
        mtn.sort(nc);

    }

}
/ definition of comparator /
class Compare_str implements Comparator < String > {

        public int compare(String one ,String two) {
                    return one.compareTo(two);
                }

}
/ is here to test whether sort: can be overwritten in the basic class LinkedList /
class LinkedList implements List < String > {

public void sort(Compare_str testcomp){
    System.out.println("test system method!");
}
/*
*TestSort.java:30: : LinkedList, ListsubList(int,int)
*class LinkedList implements List<String>{
*^
*1 
*/
public LinkedList subList(int from ,int to){};//
/*
*TestSort.java:30: : LinkedList, ListlistIterator(int)
*class LinkedList implements List<String>{
*^
*1 
*/
public Iterator<String> listIterator(int m){};//
/*
*TestSort.java:30: : LinkedList, ListlistIterator(int)
*class LinkedList implements List<String>{
*^
*TestSort.java:47: : LinkedListlistIterator(int)ListlistIterator(int)
*    public Iterator<String> listIterator(int m){};//
*                            ^
  *Iterator<String>ListIterator<String>
  *, E:
*E ListObject
*2 
*/

}