Даже первый пункт не проходит
package com.javarush.task.task18.task1803;
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
/*
Самые частые байты
*/
public class Solution {
public static void main(String[] args) throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
String fileName = br.readLine();
br.close();
ArrayList<Integer> byteArrayList = new ArrayList<>();
FileInputStream fis = new FileInputStream(fileName);
while (fis.available() > 0) {
int i = fis.read();
byteArrayList.add(i);
}
fis.close();
ArrayList<Integer> frequencyOfBytes = new ArrayList<>(byteArrayList.size());
for (int i = 0; i < frequencyOfBytes.size(); i++) {
frequencyOfBytes.set(i, Collections.frequency(byteArrayList, byteArrayList.get(i)));
}
int max = Collections.max(frequencyOfBytes); // find max of frequency
ArrayList<Integer> maxFrequencyBytes = new ArrayList<>(byteArrayList.size());
for (int i = 0; i < maxFrequencyBytes.size(); i++){
if (frequencyOfBytes.get(i) == max & !maxFrequencyBytes.contains(byteArrayList.get(i))) maxFrequencyBytes.add(byteArrayList.get(i));
}
for (Integer i: maxFrequencyBytes) {
System.out.print(i + " ");
}
}
}