Writing to a file (internal storage) and sharing it via mail/bluetooth.as a .txt file

Question

I've picked up Android only today (so I'm as new to this as it can get) and I'm trying to achieve this:

Let user input some data. Save this data as a .txt file. (in Internal Storage since my target phone will not have an SD Card). Read this .txt file and share it as an attachment via mail or share it through any other means. (Bluetooth/Whatsapp/Facebook/Drive) etc.

Here is the issue:

I'm able to let the user save the data. I'm also able to read it back. HOWEVER, when I try to share it, it goes as plain text. i.e., if I share it via GMail, it does not go as a text file attachment, rather the text itself goes as the body of the mail. Sharing it via bluetooth makes it a .html file, which can still solve my purpose provided it could be sent via mail.

My Code:

Saving data (which comes as a stream of bytes) to file:

@Override
public void onReceivedData(byte[] arg0) {
    data = new String(arg0, "UTF-8");
    String filename = "testFile.txt";
    FileOutputStream outputStream;
    try {
        outputStream = openFileOutput(filename, Context.MODE_APPEND);
        outputStream.write(data.getBytes());
        //The following 2 lines just for feedback
        data = data.concat(" Wrote to file");
        tvAppend(textView, data);
        outputStream.close();
    } catch (Exception e) {
        e.printStackTrace();
    }
}

Reading from file and sending as attachment:

Approach 1 (which results in plaintext):

    char c;
    int i;
    String dataToSend = "";
    String filename = "testFile.txt";
    FileInputStream inputStream;
    try {
        inputStream = openFileInput(filename);
        while((i=inputStream.read())!=-1)
        {
            c=(char)i;
            dataToSend += c;
        }
        inputStream.close();
    } catch (Exception e) {
        e.printStackTrace();
    }
    sendIntent.putExtra(Intent.EXTRA_TEXT, dataToSend);
    sendIntent.setType("text/plain");
    startActivity(sendIntent);

Approach 2 (which fails to work):

Intent sendIntent = new Intent();
sendIntent.setAction(Intent.ACTION_SEND);
try{
    String filePath = getFilesDir().getAbsolutePath();
    File file = new File(filePath, "testFile.txt");
    sendIntent.putExtra(Intent.EXTRA_STREAM, Uri.fromFile(file));
}
catch (Exception e)
    e.printStackTrace();
}
sendIntent.setType("*/*");
startActivity(sendIntent);

In this approach, I get the Share dialog box, but all attachments/bluetooth transfers fail.

Error messages:

Bluetooth: Unknown File; Request can't be handled correctly

Gmail Attachment:

Permission denied for the attachment

Can anyone guide me on this? I did go through the "Note" of the following and also read the documentation pages for ContentProvider and FileProvider but couldn't get it to work. I tried the "filepaths.xml" approach also but to no use, hence not posting code relevant to that approach.

Any help would be appreciated. Thanks in advance.

Answer 1

 getFilesDir() 

Delivers path to private internal memory. Reachable for your app only. The mail app has no access.

Use getExternalFilesDir() instead. Also when you write the file using FileOutputStream.

On Android 7.0 this will not work either and you have to use a file content provider then.