When testing everything works
package com.codegym.task.task18.task1803;
import java.io.FileInputStream;
import java.io.*;
import java.util.*;
/*
Most frequent bytes
*/
public class Solution {
public static void main(String[] args) throws IOException {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
String fileName= reader.readLine();
FileInputStream inStream = new FileInputStream(fileName);
ArrayList<Integer> array = new ArrayList<>();
ArrayList<Integer>array1= new ArrayList<>();
int sum = 0;
int endsum = 0;
while (inStream.available() > 0) {
int data = inStream.read();
array.add(data);
}
inStream.close();
reader.close();
for (int i = 0; i < array.size(); i++) {
for (int j = i + 1; j < array.size(); j++) {
if (array.get(i).equals(array.get(j))) {
sum++;
}
}
if (sum > endsum) {
endsum = sum;
array1.add(array.get(i));
sum = 0;
}
}
for (int result : array1) {
System.out.print(result + " ");
}
}
}