CodeGym/Help with Java Tasks/Unsure of what the problem is

Level 26

Clarksville

11.10.2021
450views
7comments

Unsure of what the problem is

Question about the task

Under discussion

To my fellow CodeGym friends, I do not know what could possibly be wrong with my code. I have spent so long working on this, and I will admit to even cheating by looking at the solution. I fail to see any cause for my lack of validation. I hope that some of you experienced solvers out there can show me where I went wrong. - The top 2 points pass, the bottom 3 fail. Thanks, Dan

The main method accepts a list of arguments.
The first argument is the full path to the fileName file.
The second argument is the path to a ZIP file.
Add the fileName file to the archive inside the "new" directory.
If the archive already has a file with the same name in the "new" directory, then replace it.

Example input:
C:/result.mp3 C:/pathToTest/test.zip

Files inside test.zip:
a.txt b.txt

After running Solution.main, the test.zip archive must contain the following:
new/result.mp3
a.txt b.txt

Hint: you need to first save the contents of all of the zip entries somewhere,
and then write all the entities together with the added file to the archive.
Don't use the file system.

Requirements:

In the main method, create a ZipInputStream for the archive (main's second argument). You need to read all of its contents.
In the main method, create a ZipOutputStream for the archive (main's second argument).
You need to write the contents of the file passed to main as the first argument to the ZipOutputStream.
You need to write all of the other content read from the ZipInputStream to the ZipOutputStream.
The archive streams must be closed.

package com.codegym.task.task31.task3105; import java.io.*; import java.nio.file.Files; import java.util.HashMap; import java.util.Map; import java.util.zip.ZipEntry; import java.util.zip.ZipInputStream; import java.util.zip.ZipOutputStream; public class Solution { public static void main(String[] args) throws IOException { HashMap<ZipEntry, byte[]> fileMap = getContents(args[1]); FileOutputStream fileOutStream = new FileOutputStream(args[1]); ZipOutputStream zipOutStream = new ZipOutputStream(fileOutStream); File originalFile = new File(args[0]); zipOutStream.putNextEntry(new ZipEntry("new/" + originalFile.getName())); Files.copy(originalFile.toPath(), zipOutStream); zipOutStream.closeEntry(); for (Map.Entry pair : fileMap.entrySet()) { ZipEntry nextZip = (ZipEntry) pair.getKey(); byte[] content = (byte[]) pair.getValue(); String fileName = nextZip.getName(); if (!fileName.equals("new/" + originalFile.getName())) { zipOutStream.putNextEntry(nextZip); zipOutStream.write(content); zipOutStream.closeEntry(); } } zipOutStream.close(); fileOutStream.close(); } private static HashMap<ZipEntry, byte[]> getContents(String args1) throws IOException { HashMap<ZipEntry, byte[]> resultMap = new HashMap<>(); FileInputStream inStream = new FileInputStream(args1); ZipInputStream zipInStream = new ZipInputStream(inStream); ZipEntry nextEntry; // Loop where nextEntry is the next file available for reading while ((nextEntry = zipInStream.getNextEntry()) != null) { ByteArrayOutputStream byteArray = new ByteArrayOutputStream(); byte[] buffer = new byte[1024]; int length; // This loop puts up to 1024 bytes of info at a time into byteArray while ((length = zipInStream.read(buffer)) > 0) { byteArray.write(buffer, 0, length); } // Now byteArray contains all bytes from the nextEntry file resultMap.put(nextEntry, byteArray.toByteArray()); } return resultMap; } }

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Guadalupe Gagnon

Level 37 , Tampa, United States

11 October 2021, 18:00

Try closing the input streams. Other than that your code seems to work.

Dan

Level 26 , Clarksville, United States

Expert

11 October 2021, 19:30

After your comment, I added

zipInStream.close();
inStream.close();

on lines 60 and 61 just before

return resultMap;

in my getContents method. Unfortunately, This is what I get for results. As you can see the bottom 3 checks fail.

Guadalupe Gagnon

Level 37 , Tampa, United States

11 October 2021, 19:33

Another theory: Maybe the task wants the ZipOutput file order to match the order the ZipInput reads the files in. It should be easy to test with your code, try returning a LinkedHashMap instead of a HashMap.

Dan

Level 26 , Clarksville, United States

Expert

11 October 2021, 21:03

If I understand you correctly, you're saying I should try making fileMap into a LinkedHashMap instead of a regular HashMap. I tried what you recommended, changing fileMap into a LinkedHashMap, and iterating through it normally in an enhanced for-loop as shown below.

for (Map.Entry pair : fileMap.entrySet()) {
     ZipEntry nextZip = (ZipEntry) pair.getKey();
     byte[] content = (byte[]) pair.getValue();
}

I didn't change how that loop functions at all, and unfortunately the result is the same. the first 2 points pass, and the final 3 points fail. Thank you for your theory though. It shows that you have a good mind when it comes to this validation software.

Dan

Level 26 , Clarksville, United States

Expert

13 October 2021, 15:42

Ok this is really weird. I've re-wrote the whole thing 3 times now, and the closest I come to passing verification is by using a program that will not actually run at all. The program that they (CodeGym) have listed as their solution uses the following to initialize their fileInputStreams list:

List<String> fileNames = new ArrayList<>();
fileNames.addAll(Arrays.asList(args).subList(1, args.length));
Collections.sort(fileNames);

for (String name : fileNames) {
    fileInputStreams.add(new FileInputStream(name));
}

The problem with that, is that FileInputStream cannot detect compressed files. So when I copy their code exactly, it gives a FileNotFoundException as soon as the first FileInputStream is initialized. If, instead, you copy the parentdirectory of the compressed files for FileInputStream, and then go through ZipInputStream.getNextEntry() one at a time, grabbing the content and putting it into a HashMap, etc., you can avoid the FileNotFound exception, as shown below

List<FileInputStream> fileStreamList = new ArrayList<>();

for (int i = 0; i < filePathList.size(); i++) {
    Path parentDirectory = Paths.get(filePathList.get(i)).getParent();
    fileStreamList.add(new FileInputStream(parentDirectory.toString()));
}
ZipInputStream zipInStream = new ZipInputStream(new SequenceInputStream(Collections.enumeration(fileStreamList)));

BUT -- As soon as you use .getParent, validation will no longer recognize that you have created an inputStream, and will fail validation. I'm so confused. Why does their Solution not even work. Am I missing something obvious here?

Guadalupe Gagnon

Level 37 , Tampa, United States

13 October 2021, 15:47

Did you see the code I shared with you in message?

Dan

Level 26 , Clarksville, United States

Expert

13 October 2021, 15:48

No, let me search for it real quick.