How do I backup a SQLite Database to a SD Card?

Question

How do I backup a SQLite Database to a SD Card? I have looked at many examples on here and none of them work for me. I have added the following lines to my manifest:

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

and the following to a fragment with a textview to click on and perform the backup:

    // Find the Text View that displays the Backup Database Button //
    TextView backupDatabaseTextView = (TextView) rootview.findViewById(R.id.backup_database_text_view);

    // Set a click listener on the backup database text view //
    backupDatabaseTextView.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {

            exportDB();

        }
    });

and the following method:

private void exportDB() {
    try {
        File sd = Environment.getExternalStorageDirectory();
        File data = Environment.getDataDirectory();

        if (sd.canWrite()) {
            String currentDBPath = "//data//" + "com.budgettrackpro.android.budgettrackpro"
                    + "//databases//" + "budgettrackpro.db";
            String backupDBPath = "BudgetTrackPro";
            File currentDB = new File(data, currentDBPath);
            File backupDB = new File(sd, backupDBPath);

            FileChannel src = new FileInputStream(currentDB).getChannel();
            FileChannel dst = new FileOutputStream(backupDB).getChannel();
            dst.transferFrom(src, 0, src.size());
            src.close();
            dst.close();
            Toast.makeText(getActivity(), "Backup Successful!",
                    Toast.LENGTH_SHORT).show();

        }
    } catch (Exception e) {

        Toast.makeText(getActivity(), "Backup Failed!", Toast.LENGTH_SHORT)
                .show();

    }
}

Answer 1

When I debug, it finds the sd card but then drops to the bottom of the try catch

I do not know how to interpret that, as I do not know which lines in that code you think represent "finds the sd card". For example, your code has nothing to do with removable storage.

So, here are various issues, in descending order of likelihood of being the source of your current difficulty (though you should fix all of them):

No Runtime Permission Support

You are running on Android 8.1. Since Android 6.0, you need to request certain permissions at runtime, and WRITE_EXTERNAL_STORAGE is among those permissions.

Hardcoded Database Path

String currentDBPath = "//data//" + "com.budgettrackpro.android.budgettrackpro"
                + "//databases//" + "budgettrackpro.db";

Never hardcode paths. Replace that with:

File currentDB = getActivity().getDatabasePath("budgettrackpro.db");

(and get rid of the File currentDB = new File(data, currentDBPath); line, as you will no longer need it)

Not Logging the Exception

While you are developing an app, log all exceptions. Add this line above your Toast.makeText() line in your catch block:

Log.e(getClass().getSimpleName(), "Exception backing up database", e);

Then, use LogCat to examine the stack trace associated with any crashes.

Doing I/O on the Main Application Thread

At best, your UI will be frozen for the duration of the exportDB() call, and your users will think that your app is broken. At worst, you will crash, because either:

• The backup is taking too long and tying up the main application thread, or
• StrictMode complains about the disk I/O on the main application thread

Please move this work to a background thread.

Not Making the Backup Visible to the User

Even once you create the file, the user will not be able to see that it exists without rebooting or waiting a few hours.