It's probably some stupid little think but i don't see it. Please help...
package com.codegym.task.task18.task1825;
import java.io.*;
import java.sql.SQLOutput;
import java.util.*;
/*
Building a file
*/
public class Solution {
public static void main(String[] args) throws IOException {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
String fileName;
Map<Integer, String> files = new HashMap<>();
while (!(fileName = reader.readLine()).equals("end")) {
int partNumber = Integer.parseInt(fileName.split("\\.part")[1]);
files.put(partNumber, fileName);
}
reader.close();
if (!files.isEmpty()) {
String newFileName = files.get(1).split("\\.part")[0];
FileOutputStream fileOutputStream = new FileOutputStream(newFileName);
List<Integer> partsNo = new ArrayList<>(files.keySet());
Collections.sort(partsNo);
for (Integer file : partsNo) {
FileInputStream fileInputStream = new FileInputStream(new File(files.get(file)));
byte[] buffer = new byte[fileInputStream.available()];
fileInputStream.read(buffer);
fileOutputStream.write(buffer);
fileInputStream.close();
}
fileOutputStream.close();
}
}
}