Extraction code not passing validation

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I felt a little like shooting in the dark on this task since we haven't been given an example of code to extract a file from a Zip yet. But I assumed the copyData method would be used for that. I googled a few options and it seemed they used code similar to copyData with a few other bits. I tried to combine them together as best I could. And I assumed my first guess would fail but I was hoping it would give me a clue as to how to proceed. It did not. So, I have no idea if I'm even on the right track with this. Take a look and let me know if I am at least close.

It's time to try to extract something. To do this, add a public void extractAll(Path outputFolder) throws Exception method to the ZipFileManager class. The Path outputFolder parameter is the path to which we will extract our archive. You already have extensive experience working with zip entries and streams, so I'll only give you some hints on how to implement this method. You'll have to think carefully about how to do the following:
1. Check whether the zip file exists
2. If the outputFolder directory does not exist, then it needs to be created, along with all the folders that contain it.
3. Inside the archive, some files may be inside folders. In this case, the ZipEntry.getName() method doesn't exactly return the file name, as might be expected from the method name. Instead, it returns the file's relative path inside the archive. This relative path should be retained after the extraction process is complete, but it will become relative to the directory where we have extracted the archive
4. Implement the ZipExtractCommand class's execute() method by analogy with our implementation of ZipCreateCommand. Make a similar try-catch block, and simply change the displayed messages so that the user knows we are currently extracting an archive, and that we need the archive's full name and the directory to which we will extract the archive. Don't forget to call the ZipFileManager class's extractAll method, and not createZip like we did in the ZipCreateCommand
5. Run the program and enjoy the extracted results

Note:
Use Files.newInputStream(Path path) and Files.newOutputStream(Path path) to get read and write streams.

Requirements:

You need to create a public void extractAll(Path outputFolder) throws Exception method in the ZipFileManager class.
The extractAll(Path outputFolder) method must throw a NoSuchZipFileException if the archive file does not exist.
The extractAll(Path outputFolder) method must create the outputFolder directory if it doesn't exist.
The extractAll(Path outputFolder) method must extract all of the files from the archive into the outputFolder directory.
The ZipExtractCommand class's execute() method must get the ZipFileManager object and extract the files to the directory specified by the user.

package com.codegym.task.task31.task3110; import com.codegym.task.task31.task3110.exception.NoSuchZipFileException; import java.io.IOException; public class Archiver { public static void main(String[] args) throws IOException { Operation operation = null; do { try { operation = askOperation(); CommandExecutor.execute(operation); } catch (NoSuchZipFileException e) { ConsoleHelper.writeMessage("You didn't select an archive or you selected an invalid file."); } catch (Exception e) { ConsoleHelper.writeMessage("An error occurred. Please check the entered data."); } } while (operation != Operation.EXIT); } public static Operation askOperation() throws IOException { ConsoleHelper.writeMessage(""); ConsoleHelper.writeMessage("Select an operation:"); ConsoleHelper.writeMessage(String.format("\t %d - Zip files into an archive", Operation.CREATE.ordinal())); ConsoleHelper.writeMessage(String.format("\t %d - Add a file to an archive", Operation.ADD.ordinal())); ConsoleHelper.writeMessage(String.format("\t %d - Remove a file from an archive", Operation.REMOVE.ordinal())); ConsoleHelper.writeMessage(String.format("\t %d - Extract an archive", Operation.EXTRACT.ordinal())); ConsoleHelper.writeMessage(String.format("\t %d - View the contents of an archive", Operation.CONTENT.ordinal())); ConsoleHelper.writeMessage(String.format("\t %d - Exit", Operation.EXIT.ordinal())); return Operation.values()[ConsoleHelper.readInt()]; } }

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Lisa L

Level 47 , Nuremberg, Germany

24 April 2022, 21:19

Maybe try to create subdirs... Eg. the outFolder is /tmp/ and the zipEntries name is /a/b/c.txt then this resolves to /tmp/a/b/c.txt and you pass that path to your fileOut stream. However you'll get an exception cause a and b do not exist.

try {
            Path outFile = Paths.get("c:/temp/A/B/C.txt");

/*
            Path parent = outFile.getParent();
            if (!Files.exists(parent))
                Files.createDirectories(parent);
*/


            OutputStream out = Files.newOutputStream(outFile);
            out.write(68);
        } catch (IOException ioe) {
            throw new RuntimeException(ioe);
        }

Justin Smith

Level 41 , Greenfield, USA, United States

25 April 2022, 12:29

Ah, I see. I used createDirectories to create the location where the files should be extracted, but I need to use it again if the files in the zip are also in subfolders. This is what I have now. It still doesn't pass, though.

public void extractAll(Path outFolder) throws Exception
{
    if(!Files.isRegularFile(zipFile))
    {
        throw new NoSuchZipFileException();
    }
    if(Files.notExists(outFolder))
    {
        Files.createDirectories(outFolder);
    }
    try(ZipInputStream zipInputStream = new ZipInputStream(Files.newInputStream(zipFile)))
    {
        ZipEntry zipEntry = zipInputStream.getNextEntry();
        while(zipEntry != null)
        {
            Path filePath = outFolder.resolve(zipEntry.getName());
            if(Files.notExists(filePath.getParent()))
            {
                Files.createDirectories(filePath.getParent());
            }
            try(FileOutputStream fileOut = new FileOutputStream(filePath.toFile()))
            {
                copyData(zipInputStream, fileOut);
            }
            zipEntry = zipInputStream.getNextEntry();
        }
    }
}

Lisa L

Level 47 , Nuremberg, Germany

25 April 2022, 13:02

solution

I compared to mine and it looks similar... and copyData() looks good, too

public void extractAll(Path outputFolder) throws Exception {
    // Check whether the zip file exists
    if (!Files.isRegularFile(zipFile)) {
        throw new NoSuchZipFileException();
    }

    try (ZipInputStream zipInputStream = new ZipInputStream(Files.newInputStream(zipFile))) {
        // Create the output directory if it doesn't exist
        // probably not necessary cause we do that in the while loop again
        if (Files.notExists(outputFolder))
            Files.createDirectories(outputFolder);

        // Go through the contents of the zip stream (file)
        ZipEntry zipEntry = zipInputStream.getNextEntry();

        while (zipEntry != null) {
            String fileName = zipEntry.getName();
            Path fileFullName = outputFolder.resolve(fileName);

            // Create the necessary directories
            Path parent = fileFullName.getParent();
            if (Files.notExists(parent))
                Files.createDirectories(parent);

            try (OutputStream outputStream = Files.newOutputStream(fileFullName)) {
                copyData(zipInputStream, outputStream);
            }
            zipEntry = zipInputStream.getNextEntry();
        }
    }
}

Justin Smith

Level 41 , Greenfield, USA, United States

25 April 2022, 14:29

I think line 21 (in my code) is the problem. You have Files.newOutputStream. I am using new FileOutputStream with the toFile method. I got my code syntax when googling for how to extract the data here: https://zetcode.com/java/zipinputstream/ I'll see what happens if I change that part. Yep, that solved it! An example of why I don't like googling for the needed solution. 😅

Jakub Raczkowski

Level 41 , Polska, Poland

7 November 2023, 08:48

And for these of you who still struggle with this task, even after applying hints from Justin and Lisa, check your copyData() method. I had a simple:

while (in.available() > 0){
            out.write(in.read());
        }

This had passed previous validation, however I noticed it puts some weird 'ÿ' character at the end of my zipped text test file. When I changed it to the one from Justin, validation finally passed:

private void copyData(InputStream in, OutputStream out) throws Exception {

//        while (in.available() > 0){
//            out.write(in.read());
//        }

        byte[] buffer = new byte[8 * 1024];
        int len;
        while ((len = in.read(buffer)) > 0) {
            out.write(buffer, 0, len);
        }
    }