Could someone tell me whats wrong in my code?

Question about the task

Building a file

Java Core, Level 8, Lesson 11

Under discussion

Hi, it keeps saying that i didnt closed the streams but i think i did or am i wrong? Thanks in advance

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.nio.ByteBuffer; import java.nio.charset.StandardCharsets; 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)); String readString; TreeSet<String> treeSet = new TreeSet<>(); ArrayList<String> list = new ArrayList<>(); int count = 1; while ((!(readString = reader.readLine()).equals("end"))) { String filePath = "C:/temp/" + readString; try (FileOutputStream stream = new FileOutputStream(filePath)) { } treeSet.add(new StringBuilder(filePath).reverse().toString()); } for (String s : treeSet) { list.add(new StringBuilder(s).reverse().toString()); } try (FileOutputStream stream = new FileOutputStream("C:/temp/Lion.avi")) { for (String s : list) { try (FileInputStream stream1 = new FileInputStream(s)) { byte[] buffer = new byte[stream1.available()]; while (stream1.available() > 0) { int bytesRead = stream1.read(buffer); stream.write(buffer, 0 ,bytesRead); } } } } } }

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Guadalupe Gagnon

Level 37 , Tampa, United States

8 March 2022, 21:18

useful

#1 The task does not say that the files are located on your computer. Adding "C:/" to the beginning of each file read in will automatically fail validation. #2 I think that this line:

treeSet.add(new StringBuilder(filePath).reverse().toString());

by reversing the input String is an attempt to put the number of the part at the start of the String and sort by by that, but it does not work. While that may work if the part numbers are only between 1 and 9, what would be the results when you have over 10 files? Example: If you take the numbers 1-15 as Strings, reverse them, and sort them alphabetically the result would be: 01, 1, 11, 2, 21, 3, 31, 4, 41, 5, 51, 6, 7, 8 ,9 Which is sorted correctly in alphabetic order. #3 The task specifically says that the code should figure out the file name from the parts given. This code hard codes in "lion.avi" as the file name which will automatically be another validation fail. So to pass this task the code needs to be abstracted more to remove any hard references to the location of files on your computer as well as the file name "lion.avi". You will also need to fix the logical mistake that sorting numbers alphabetically does not sort them numerically as well as making sure not to reverse the digits in the part numbers.