CodeGym/Help with Java Tasks/Red lights everywhere!

Level 41

Rybnik

03.06.2021
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10comments

Red lights everywhere!

Question about the task

Adding a file to an archive

Java Collections, Level 1, Lesson 6

Under discussion

It's my second approach - still all I can see is red light! Any sugesstions ?

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.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.nio.file.*; import java.util.HashMap; import java.util.Map; import java.util.zip.ZipEntry; import java.util.zip.ZipInputStream; import java.util.zip.ZipOutputStream; /* Adding a file to an archive */ public class Solution { public static void main(String[] args) throws IOException { //My new strategy: //1 - create Map with file content as byte[] and file-name as String //2 - put to Map file-to-add-to-archive with it's name prefixed with "new\" //3 - Unzip all files from archive to Map //4 - Iterate through map and write bytes to entries Map<byte[],String> map = new HashMap<>(); //1 is done! //2 - put to Map file-to-add-to-archive with it's name prefixed with "new\" File fileToAddToArchive = new File(args[0]); //file to add to archive FileInputStream fileInputStream = new FileInputStream(fileToAddToArchive); while (fileInputStream.available()>0){ byte[] byteArray = new byte[124]; fileInputStream.read(byteArray); map.put(byteArray, "new\\" + fileToAddToArchive.getName()); } fileInputStream.close(); //2 is done! //printMap(map); //3 - Unzip all files from archive to Map File zipFile = new File(args[1]); //archive ZipInputStream zipInputStream = new ZipInputStream(new FileInputStream(zipFile)); ZipEntry a; while ((a = zipInputStream.getNextEntry())!=null){ if (a.getName().equals("new\\" + Paths.get(args[0]).getFileName())) continue; if (!a.isDirectory()) { //if this is not a directory (this function is not working properly) while (zipInputStream.available() > 0) { byte[] byteArray = new byte[124]; zipInputStream.read(byteArray); map.put(byteArray,a.getName()); zipInputStream.closeEntry(); } } } zipInputStream.closeEntry(); zipInputStream.close(); //3 is done! //printMap(map); //4 - Iterate through map and write bytes to entries ZipOutputStream zipOutputStream = new ZipOutputStream(new FileOutputStream(args[1])); for (Map.Entry<byte[],String> para : map.entrySet()){ zipOutputStream.putNextEntry(new ZipEntry(para.getValue())); zipOutputStream.write(para.getKey()); } zipOutputStream.flush(); zipOutputStream.close(); //4 is done! } }

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Daniel

Level 41 , Rybnik, Poland

6 June 2021, 13:38

I tried this code with files much bigger than buffer and works great but validator is stubborn as a mule! - but now I'm just wondering how big can a ByteArrayOutputStream be ? Integer.MAX_VALUE ? What about bigger files ? Even in CodeGym solution there is only space available for max int - what do you think ?

Daniel

Level 41 , Rybnik, Poland

5 June 2021, 13:41

Thanks for the hint - now I'm using ByteArrayOutputStream to create a byte[] but nothing changed Look here please:

//3 - Unzip all files from archive to Map
        File zipFile = new File(args[1]); //archive
        ZipInputStream zipInputStream = null;
        try {
            zipInputStream = new ZipInputStream(new FileInputStream(zipFile));
            ZipEntry a;
            byte[] byteArray = new byte[1024];
            while ((a = zipInputStream.getNextEntry())!=null) {
                if (a.getName().equals("new\\" + Paths.get(args[0]).getFileName())) continue;
                while (zipInputStream.available() > 0) {
                    ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
                    int length = 0;
                    while ((length = zipInputStream.read(byteArray)) > 0) {
                        byteArrayOutputStream.write(byteArray, 0, length);
                    }
                    map.put(byteArrayOutputStream.toByteArray(), a.getName());
                    zipInputStream.closeEntry();
                }
            }
            zipInputStream.closeEntry();
            zipInputStream.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        //3 is done!

Guadalupe Gagnon

Level 37 , Tampa, United States

6 June 2021, 19:08

Remove lines 10, 18, and 20. Did you also fix the problem in step 2 as well as step 3? Also, what are the catch blocks for? The default behavior for uncaught exceptions is to print the stack trace. It doesn't make sense to code this behavior in, especially since if there is an error here the program shouldn't continue to step 4.

Daniel

Level 41 , Rybnik, Poland

6 June 2021, 19:44

I // lines 10, 18 and 20, I have fixed also step 2 and also // lines for step 2 - program still works good but all lights are red. About try-catch -> I think I need to wrap all my code into one big try blokc -> I will do it later and check again

Guadalupe Gagnon

Level 37 , Tampa, United States

6 June 2021, 22:34

dont do that. Just add to main that it throws Exception: psvm(S[] a) throws Exception That is the same exact thing as wrapping in a big "try catch" when your catch block isn't used to handle an exception.

Daniel

Level 41 , Rybnik, Poland

7 June 2021, 08:32

Still nothing :(, still works fine with 3 pdf files > 50Mb inside zip and 1 pdf file >50Mb to add to archive All works great:

public class Solution {
    public static void main(String[] args) throws IOException {
        //My new strategy:
        //1 - create Map with file content as byte[] and file-name as String
        //2 - put to Map file-to-add-to-archive with it's name prefixed with "new\"
        //3 - Unzip all files from archive to Map
        //4 - Iterate through map and write bytes to entries

        //File fileToAddToArchive = new File(args[0].substring(1)); //file to add to archive
        File fileToAddToArchive = new File(args[0]); //file to add to archive
        //File zipFile = new File(args[1].substring(1)); //archive
        File zipFile = new File(args[1]); //archive

        Map<byte[],String> map = new HashMap<>(); //Map to store file content and names
        //1 is done!

        //2 - put to Map file-to-add-to-archive with it's name prefixed with "new\"
        FileInputStream fileInputStream = new FileInputStream(fileToAddToArchive);
        ByteArrayOutputStream byteArrayOutputStream1 = new ByteArrayOutputStream();
        byte[] byteArray1 = new byte[1024];
        while (fileInputStream.available()>0){
            int length1=0;
            length1=fileInputStream.read(byteArray1);
            byteArrayOutputStream1.write(byteArray1,0,length1);
        }
        map.put(byteArrayOutputStream1.toByteArray(), "new/" + fileToAddToArchive.getName());
        fileInputStream.close();
        //2 is done!

Daniel

Level 41 , Rybnik, Poland

7 June 2021, 08:32

Rest of code:

//3 - Unzip all files from archive to Map
        ZipInputStream zipInputStream = new ZipInputStream(new FileInputStream(zipFile));
        ZipEntry a;
        byte[] byteArray = new byte[1024];
        while ((a = zipInputStream.getNextEntry())!=null) {
            if (a.getName().equals("new/" + Paths.get(String.valueOf(fileToAddToArchive)).getFileName())) continue;
            ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
            int length = 0;
            while ((length = zipInputStream.read(byteArray)) > 0) {
                byteArrayOutputStream.write(byteArray, 0, length);
            }
            map.put(byteArrayOutputStream.toByteArray(), a.getName());
            zipInputStream.closeEntry();
            }
            zipInputStream.close();
        //3 is done!

        //4 - Iterate through map and write bytes to entries
        ZipOutputStream zipOutputStream = new ZipOutputStream(new FileOutputStream(zipFile));
        for (Map.Entry<byte[],String> para : map.entrySet()){
            zipOutputStream.putNextEntry(new ZipEntry(para.getValue()));
            zipOutputStream.write(para.getKey());
        }
        zipOutputStream.flush();
        zipOutputStream.close();
        //4 is done!
    }
}

Guadalupe Gagnon

Level 37 , Tampa, United States

7 June 2021, 13:25

The only real issue I see with the code is that:

zipOutputStream.closeEntry();

should be after:

ipOutputStream.write(para.getKey());

(this is in the loop that writes back to the ZipFile)

Daniel

Level 41 , Rybnik, Poland

7 June 2021, 14:00

Added but nothing changed :

//4 - Iterate through map and write bytes to entries
        ZipOutputStream zipOutputStream = new ZipOutputStream(new FileOutputStream(zipFile));
        for (Map.Entry<byte[],String> para : map.entrySet()){
            ZipEntry zipEntry = new ZipEntry(para.getValue());
            zipEntry.setSize(para.getKey().length);
            zipOutputStream.putNextEntry(zipEntry);
            zipOutputStream.write(para.getKey());
            zipOutputStream.closeEntry();
        }
        zipOutputStream.flush();
        zipOutputStream.close();
        //4 is done!
    }
}

Guadalupe Gagnon

Level 37 , Tampa, United States

4 June 2021, 16:25

#1 The files can be any size. You are reading the the first file 124 bytes at a time. That is going to end up with the map being, in completely random order, a whole bunch pieces of the whole file of byte[] arrays that are 124 bytes. This isn't going to work. #1a This mistake is also repeated when reading each file in the zip directory