В чем ошибка
package com.javarush.task.task18.task1825;
import java.io.*;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.Set;
import java.util.TreeSet;
/*
Собираем файл
*/
public class Solution {
public static void main(String[] args) throws IOException {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
String s;
String[] a = new String[1];
int [] allParts = new int[256];
while (!((s = reader.readLine()).equals("end"))){
a = s.split(".part");
try (FileInputStream fileInputStream = new FileInputStream(s)) {
while (fileInputStream.available()>0){
allParts[Integer.parseInt(s.substring(s.length()-1))] = fileInputStream.read();
}
}
}
FileOutputStream final1 = new FileOutputStream(a[0]);
for (int i = 0; i <allParts.length ; i++) {
if (allParts[i]!=0) {
final1.write(allParts[i]);
}
}
final1.close();
}
}