Подскажите что не так с решением?

package com.javarush.task.task18.task1823;

import java.io.*;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;

/*
Нити и байты
*/

public class Solution {
    public static Map<String, Integer> resultMap = new HashMap<String, Integer>();

    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        String file = null;
        //ReadThread readThread;
        while(true){
            file = reader.readLine();

            if(!(file.equals("exit"))){
                ReadThread thread = new ReadThread(file);
                thread.start();
            }else
                break;
        }
        reader.close();
    }

    public static class ReadThread extends Thread {
        String fileName;
        public ReadThread(String fileName) throws IOException {
            //implement constructor body
            super();
            this.fileName = fileName;
        }
        public void run(){
            try {
                ArrayList<Integer> list2 = new ArrayList<>();
                FileInputStream fileInputStream = new FileInputStream(fileName);
                fileInputStream.close();
                Map<Integer, Integer> map = new HashMap<>();
                while (fileInputStream.available() > 0) {
                    int n = fileInputStream.read();
                    list2.add(n);
                }
                int count=0;
                int n = 0;
                int element=0;
                for(int i = 0; i<list2.size();i++){
                    for(int j=0;j<list2.size();j++){
                        if(list2.get(i).equals(list2.get(j))){
                            count++;
                        }
                    }
                    if(count>n){
                        n = count;
                        element = list2.get(i);
                    }
                    count=0;
                }
                fileInputStream.close();
                resultMap.put(fileName, element);

            }catch (Exception e){
                e.printStackTrace();
            }
        }
        // implement file reading here - реализуйте чтение из файла тут
    }
}