создал файл без .partN
String parentDir = new File(firstFile).getParent();
String resultFileName = firstFile.substring(0, firstFile.lastIndexOf(".part"));package com.javarush.task.task18.task1825;
import java.io.*;
import java.nio.file.Files;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.Scanner;
import java.util.Set;
import java.util.TreeSet;
/*
Собираем файл
*/
public class Solution {
public static void main(String[] args) throws IOException {
Scanner scanner = new Scanner(System.in);
List<String> list = new ArrayList<>();
String fileName = scanner.nextLine();
while (!fileName.equals("end")) {
list.add(fileName);
fileName = scanner.nextLine();
}
scanner.close();
list.sort(String::compareTo);
// Получаем путь и имя результирующего файла
String firstFile = list.get(0);
String parentDir = new File(firstFile).getParent();
String resultFileName = firstFile.substring(0, firstFile.lastIndexOf(".part"));
String fullPath = (parentDir != null ? parentDir + File.separator : "") + resultFileName;
try (FileOutputStream outputStream = new FileOutputStream(fullPath)) {
byte[] buffer = new byte[1024];
for (String partFile : list) {
try (FileInputStream inputStream = new FileInputStream(partFile)) {
int bytesRead;
while ((bytesRead = inputStream.read(buffer)) != -1) {
outputStream.write(buffer, 0, bytesRead);
}
}
}
}
}
}