Android Kotlin: Getting a FileNotFoundException with filename chosen from file picker?

Question

I'm working on an Android application where one of the features is to let the user choose a file to open (I'm wanting to open a plain text .txt file). I've worked on Android apps before with Java, but for this one, I'm using Kotlin, and it's my first time using Kotlin.

I currently have the app display a file chooser and let the user tap the file they want to open. Then I'm trying to use a File object to open the file and do a forEachLine loop. But for some reason, it's throwing a java.io.FileNotFoundException (No such file or directory) with the file chosen from the file picker. I'm not sure what's wrong, and if I have to do some conversion to convert the file path?

The code for my 'load' button:

val btn_load: Button = findViewById<Button>(R.id.btn_load_puzzle)
    btn_load.setOnClickListener {
        val intent = Intent()
            .setType("*/*")
            .setAction(Intent.ACTION_GET_CONTENT)

        startActivityForResult(Intent.createChooser(intent, "Select a file"), 111)
    }

My function to respond to the file selection:

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    super.onActivityResult(requestCode, resultCode, data)

    // Selected a file to load
    if ((requestCode == 111) && (resultCode == RESULT_OK)) {
        val selectedFilename = data?.data //The uri with the location of the file
        if (selectedFilename != null) {
            val filenameURIStr = selectedFilename.toString()
            if (filenameURIStr.endsWith(".txt", true)) {
                val msg = "Chosen file: " + filenameURIStr
                val toast = Toast.makeText(applicationContext, msg, Toast.LENGTH_SHORT)
                toast.show()
                File(selectedFilename.getPath()).forEachLine {
                    val toast = Toast.makeText(applicationContext, it, Toast.LENGTH_SHORT)
                    toast.show()
                }
            }
            else {
                val msg = "The chosen file is not a .txt file!"
                val toast = Toast.makeText(applicationContext, msg, Toast.LENGTH_LONG)
                toast.show()
            }
        }
        else {
            val msg = "Null filename data received!"
            val toast = Toast.makeText(applicationContext, msg, Toast.LENGTH_LONG)
            toast.show()
        }
    }
}

The FileNotFound exception is thrown on the line where it creates the File object to do the forEachLine loop:

java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=111, result=-1, data=Intent { dat=content://com.android.externalstorage.documents/document/0000-0000:Sudoku puzzles/hard001.txt flg=0x1 }} to activity {com.example.sudokusolver/com.example.sudokusolver.MainActivity}: java.io.FileNotFoundException: /document/0000-0000:Sudoku puzzles/hard001.txt (No such file or directory)

Answer 1

If you are getting "msf:xxx" in URI, use below solution where I have created temp file in app cache directory and deleted same file after completion of my task:

if (id != null && id.startsWith("msf:")) {
                    final File file = new File(mContext.getCacheDir(), Constant.TEMP_FILE + Objects.requireNonNull(mContext.getContentResolver().getType(imageUri)).split("/")[1]);
                    try (final InputStream inputStream = mContext.getContentResolver().openInputStream(imageUri); OutputStream output = new FileOutputStream(file)) {
                        final byte[] buffer = new byte[4 * 1024]; // or other buffer size
                        int read;

                        while ((read = inputStream.read(buffer)) != -1) {
                            output.write(buffer, 0, read);
                        }

                        output.flush();
                        return file;
                    } catch (IOException ex) {
                        ex.printStackTrace();
                    }
                    return null;
                }

I have fixed this issue and it's working 100% for msf. :)

Also Delete the temp file after the completion of your work:

private void deleteTempFile() {
        final File[] files = requireContext().getCacheDir().listFiles();
        if (files != null) {
            for (final File file : files) {
                if (file.getName().contains(Constant.TEMP_FILE)) {
                    file.delete();
                }
            }
        }
    }

Here TEMP_FILE value is "temp."

Answer 2

You cannot open a Java File on a ÙRI converted to a String, the "path" section of the URI has no relation to a physical file location.

Use a contentResolver to get a Java FileDescriptor to open the file with.

val parcelFileDescriptor: ParcelFileDescriptor =
            contentResolver.openFileDescriptor(uri, "r")
    val fileDescriptor: FileDescriptor = parcelFileDescriptor.fileDescriptor

This method is compatible with Android 10 where file paths for non App private directories are not usuable.

https://developer.android.com/training/data-storage/shared/documents-files

Answer 3

Open a Bitmap file given its URI:

private Bitmap getBitmapFromUri(Uri uri) throws IOException {
    ParcelFileDescriptor parcelFileDescriptor =
            getContentResolver().openFileDescriptor(uri, "r");
    FileDescriptor fileDescriptor = parcelFileDescriptor.getFileDescriptor();
    Bitmap image = BitmapFactory.decodeFileDescriptor(fileDescriptor);
    parcelFileDescriptor.close();
    return image;
}

Answer 4

For msf: file uri format, present from Andorid 10.

you can check this solution: https://stackoverflow.com/a/68827976/15342371

This fetch path without copying the file.