All these nio tasks are frustrating as hell...

Frage zur Aufgabe

In der Diskussion

code works and CG is nitpicking, wanting to see that one special thing they don't talk about in their descriptions. What about here. I'm reading the zip archive. So what is the problem? Do they ask to read the zips content into memory? Do they just want me to try to validate more than 100 times? The FileTree task already drove me crazy (rally this time). It's about nio and they ask for File. Then lambdas don't work on their server, next type inference throws errors on CG box. Renaming has to be done right away otherwise you're in validation hell. After 30 tries I added a linebreak between written file contents and finally it worked. Why can't they just say 'we want to see things exactly this or that way... to the POINT'. This pisses me off big time. Sorry guys 😜🤪 Oh, I just see that CG is using the version where I commented out the try block to see if that is the problem. So don't mind the missing close calls.

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.

Anforderungen:

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.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.nio.file.*; 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 { if (args[0] == null || args[1] == null) throw new IllegalArgumentException(); Path fileName = Paths.get(args[0]); Path zipFile = Paths.get(args[1]); Path newPath = Paths.get("new"); // here we copy the content of the zipFile Path tempZip = Files.createTempFile("zip", ".zip"); // try (ZipInputStream zin = new ZipInputStream(new FileInputStream(zipFile.toString())); // ZipOutputStream zout = new ZipOutputStream(new FileOutputStream(tempZip.toString()))) { ZipInputStream zin = new ZipInputStream(new FileInputStream(zipFile.toString())); ZipOutputStream zout = new ZipOutputStream(new FileOutputStream(tempZip.toString())); // get the realtive path of the filename to add inside the zip archive, as said we want to check if it exists String toAddRealativePath = newPath.resolve(fileName.getFileName()).toString(); // loop over all zipEntries of the orig file ZipEntry zipEntry; while ((zipEntry = zin.getNextEntry()) != null) { // we have the input zip entry open // first check if it matches the name of the toAdd file, if so, skip if (!zipEntry.getName().equals(toAddRealativePath)) { // then create a ZipEntry for the output file, the temp file // it has the same credentials as the in zipEntry ZipEntry outZipEntry = new ZipEntry(zipEntry); zout.putNextEntry(outZipEntry); // copy, I use a byte array as buffer instead of a BufferedStream int len; byte[] buffer = new byte[1024 * 8]; while ((len = zin.read(buffer)) > 0) { // available did not work zout.write(buffer, 0, len); } zout.closeEntry(); zin.closeEntry(); } } // now add the fileName ZipEntry outZipEntry = new ZipEntry(toAddRealativePath); zout.putNextEntry(outZipEntry); // instead of using the copy method it probably would be more consistent to outsource the copy routine above // and reuse this as method here Files.copy(fileName, zout); zout.closeEntry(); //} // end try // if we are here, then no exception occurred and we can move the temp zip file to the orig location Files.deleteIfExists(zipFile); Files.move(tempZip, zipFile); } }

Kommentare (6)

Beliebt
Neu
Alt

Du musst angemeldet sein, um einen Kommentar schreiben zu können

Guadalupe Gagnon

Level 37 , Tampa, United States

14 Dezember 2021, 15:03

First, get rid of lines 18 and 19. If no args are passed in then args[0] will be an empty input and there wont be an args[1], so that would throw an index out of bounds exception when trying to check if it is null. Second, line 26 in codegym will automatically fail any task where it does not specifically state to create a temp file. My theory is that this is because the validation system is not a computer with a storage device. It uses reflection to intercept calls to the different aspects of the tested program (method calls, streams, etc) to test that the directions are being followed. When the conditions don't specify to create a temp file then the ability to intercept that call is not programmed in and exceptions occur. Also, the last couple of lines (66 and 67) are most likely going to create problems with validation because of my theory of the validation system not having/being a hard drive. ↑ one, two, or all three of these is why every requirement is failing When they say to save all the data somewhere, I believe they are meaning in the short term (such as a collection). I personally used HashMap on this task to save the path of each file and the bytes. Try removing the above, then switching to storing the data within a code structure and see what the results are.

Lisa

Level 41

14 Dezember 2021, 20:43

OK, little bit more green now. I have rewritten nearly everything. A class as data holder that I can add to the map instead of a Byte array. That map I fill in the beginning. Then I create a ZipOutputStream overwriting the original zip, first adding the args[0] file and then the rest of the original zip. As the approach before it's working without issues (visible to me) when I did my tests still no luck validating. I really hate these tasks. CG would better do some fine tuning here than to add no beginners tasks. Totally annoying. Eg. that: zout.write(Files.readAllBytes(fileName)); won't validate. Mentor tells me to use Files.copy() and then ... bad luck, baby, requirements 3 and 4 didn't do it.

Lisa

Level 41

14 Dezember 2021, 20:43

public static void main(String[] args) throws IOException {

    Path fileName = Paths.get(args[0]);
    Path zipFile = Paths.get(args[1]);
    Path newPath = Paths.get("new");
    // map to hold the content of the zip
    Map<ZipEntry, Entry> zipContent = zipToMap(zipFile);


    try (ZipOutputStream zout = new ZipOutputStream(new FileOutputStream(args[1]))) {
        // get the realtive path of the filename to add inside the zip archive, as said we want to check if it exists
        Path toAddRealativePath = newPath.resolve(fileName.getFileName());
        // add the args[0] file to the zip file
        zout.putNextEntry(new ZipEntry(toAddRealativePath.toString()));
        // zout.write(Files.readAllBytes(fileName)); //  not validating either, mentor talks about:Files.copy()
        Files.copy(fileName, zout); // still no luck... f..ck
        zout.closeEntry();

        // write all data from the map back to the zip except new/filename
        for (Map.Entry<ZipEntry, Entry> element : zipContent.entrySet()) {
            ZipEntry zipEntry = element.getKey();
            Entry entry = element.getValue();

            if (!Paths.get(zipEntry.getName()).equals(toAddRealativePath)) { // don't copy over the eventually existing fileName
                zout.putNextEntry(zipEntry);
                zout.write(entry.getContent());
                zout.closeEntry();
            }
        }
    }
}

Lisa

Level 41

14 Dezember 2021, 20:44

private static Map<ZipEntry, Entry> zipToMap(Path zipFile) throws IOException {
    Map<ZipEntry, Entry> map = new HashMap<>(); // create the map
    try (ZipInputStream zin = new ZipInputStream(new FileInputStream(zipFile.toString()))) { // ZipInputStream
        ZipEntry zipEntry;
        while ((zipEntry = zin.getNextEntry()) != null) { // loop over all ZipEntries
            try (ByteArrayOutputStream baos = new ByteArrayOutputStream()) { // open a ByteArrayOutputStream to save the read ZipEntry
                int len;
                byte[] buffer = new byte[1024 * 8];
                while ((len = zin.read(buffer)) > 0) // read the zipEntry
                    baos.write(buffer, 0, len); // and write it to the ByteArrayOutputStream

                // save data in baos and ZipEntry to map
                map.put(zipEntry, new Entry(baos.toByteArray())); // Entry is just a data container so I do not need to use a wrapper
            }
            zin.closeEntry(); // close current ZipEntry before iterating over the next
        }
    }
    return map;
}

class Entry {
    private byte[] content;

    public Entry(byte[] content) {
        this.content = content;
    }

    public byte[] getContent() {
        return content;
    }
}

Lisa

Level 41

14 Dezember 2021, 20:59

after playing with the unzipping task I've seen that this won't validate, too. And the reason there was the usage of Path objects (validation did not recognize a Path.toString in a streams constructor). So I think this may be here the reason, too. Tomorrow I'll rewrite this task to only use the old File class instead of Path. Maybe this will help.

Lisa

Level 41

16 Dezember 2021, 09:12

@*#%!$ Task, for now you won... but I'll be back! THAT IS A ThREAT!