Copying to new file

Question about the task

Building a file

Java Core, Level 8, Lesson 11

Under discussion

Why are the files not being copied and added to the new file?

Let's build a file from various pieces.
Read file names from the console.
Each file has a name: <someName>.partN.

For example, Lion.avi.part1, Lion.avi.part2, ..., Lion.avi.part37.

The file names are supplied in random order. The word "end" is used to stop reading in file names.
In the folder where all the files are located, create a file without the "part" suffix, i.e. without ".<partN>".

For example, Lion.avi.

Use a buffer to copy all the bytes from the partial files to the created file.
Copy the first in the proper order, first the first part, then the second, ..., finally - the last part.
Close the streams.

Requirements:

The program must read file names from the console until the word "end" is entered.
Create a stream to write to the file without the "part" suffix (".<partN>") in the folder with all the "part" files.
Copy all the bytes from the *.partN files to the new file.
You should use a buffer for the reading and writing.
The file streams must be closed.
Don't use static variables.

package com.codegym.task.task18.task1825; import java.io.*; import java.util.ArrayList; import java.util.Comparator; import java.util.Set; import java.util.TreeSet; /* Building a file */ public class Solution { public static void main(String[] args) throws IOException { BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); FileInputStream inputStream; FileOutputStream outputStream; String fileName = ""; String compiledFile = ""; Set<File> order = new TreeSet<>(); while (!(fileName = reader.readLine()).equals("end")) { if (fileName.contains(".part")) { compiledFile = fileName.split(".part")[0]; order.add(new File(fileName)); } } outputStream = new FileOutputStream(compiledFile); for (File each : order) { inputStream = new FileInputStream(each); byte[] data = new byte[inputStream.available()]; inputStream.read(data); outputStream.write(data); inputStream.close(); } outputStream.close(); } static class CompareFiles implements Comparator<File> { @Override public int compare(File o1, File o2) { return o1.getName().compareTo(o2.getName()); } } }

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Level 41 , Wilson, United States

11 September 2021, 16:27

From reading others' answers, I think what worked was to not use the File class so I didn't implement it as above. I don't know if it has something to do with the validator or not but that, BufferedOutputStream, BufferedInputStream, and just ensuring that the items are listed in order should fare thee well.

Guadalupe Gagnon

Level 37 , Tampa, United States

13 September 2021, 16:01

The problem in the above code is that the files were not sorted properly. The default would be to sort alphabetically, however in this code it should be sorted numerically. I would figure that your new code solved this problem. Run this code to see how "part#" is sorted alphabetically:

public static void main(String[] args) {
   // these would be "user" inputs
   String[] test = {"f.part1", "f.part2", "f.part3", "f.part11", "f.part12", "f.part21", "f.part22"};

   Set<File> files = new TreeSet<>();

   // adding the user inputs to the TreeSet<File>
   for(String x : test) files.add(new File(x));

   // print results
   System.out.println(files);
}