Java Server Side to find longest isogram from a list of strings

Question

A client is sending a server a paragraph in the form of a list of string, each string is one line of the paragraph, number of lines, and an operation to do. Server side I need to find the longest isogram in the paragraph and return it to the client.

Here is what I have so far but I do not think it is correct:

public  static  String  long_isogram(List<String> par){
       int n = par.size();
       String tempWordOne = "";
       String tempWordTwo = "";
       for (int i = 0; i < n; i++){
            String[] arrOfStr = par.get(i).split(" ");
       }
       for (int i = 0; i < arrOfStr.size(); i++){
           for (int j = 0; j < arrOfStr[i].length; j++){
               for (int k = j + 1; k < arrOfStr[i].length; k++){
                   if (arrOfStr[i].charAt(j) != arrOfStr[i].charAt(k)){
                        tempWordOne = arrOfStr[i];
                        if(tempWordOne.length() > tempWordTwo.length()){
                            tempWordTwo = tempWordOne;
                        }
                   }
               }
           }
       }
    }//end long_isogram