Error reading Android SQLite database using Kotlin

Question

When running the code below I get the error message:

java.lang.RuntimeException: Unable to start activity
 ComponentInfo{com.example.songapp/com.example.songapp.MainActivity}: java.io.FileNotFoundException:
 /data/data/com.example.songapp/databases/songs.db: open failed: ENOENT (No such file or directory)

The code that gives error is this:

@Throws(IOException::class)
fun copyDataBase(context: Context, OUTPUT_DB_PATH: String, DB_NAME: String) {
    print("*** in copyDataBase ***")
    // Path to output database path (application database path).
    var APP_DB_FILE_PATH = OUTPUT_DB_PATH + "/" + DB_NAME

    // Path to input database file.
    var INPUT_DB_PATH = "database/" + DB_NAME

    // Open your local db as the input stream
    // This is how to get path from assets directory
    val databaseInput: InputStream = context.assets.open(INPUT_DB_PATH)

    // Open the empty db as the output stream
    val databaseOutput: OutputStream = FileOutputStream(APP_DB_FILE_PATH)

    // Transfer bytes from the inputfile to the outputfile
    val buffer = ByteArray(1024)
    var length: Int
    while (databaseInput.read(buffer).also { length = it } > 0) {
        databaseOutput.write(buffer, 0, length)
    }

    // Close the streams
    databaseOutput.flush()
    databaseOutput.close()
    databaseInput.close()
}

This is being called in the main activity as follows:

var DB_PATH = "/data/data/com.example.songapp/databases/"
var DB_NAME = "songs.db"

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        // Get context and supply it to the function
        // This is where error happens, by disabling this the app run successful.
        copyDataBase(this, DB_PATH, DB_NAME)

        setContent {
            Column() {
                TopAppBar(title = { Text(text = "Nyimbo") })
                ScrollableColumn(Modifier.fillMaxWidth()
                    .padding(10.dp)) {
                    lyricsPageComposable(lyricsMap = songMap)
                }
            }
        }
    }
}

I have a pre-populated SQLite database in the assets directory assets/database/songs.db and I expect it to be copied into /data/data/com.example.songapp/databases/songs.db. I do not know how to check whether copying has succeeded. What am I missing here? I know that the database file could not be found. Is that the path is not right? Could it be that the database was not copied? How could I tell? I'm using a physical Android phone for testing the app.

Answer 1

When running the code below I get the error message

Most likely, /data/data/com.example.songapp/databases/ does not yet exist as a directory.

This is being called in the main activity as follows

Please do not hard-code paths. You can get the standard location for a database by calling getDatabasePath() on your Activity or other Context.

I do not know how to check whether copying has succeeded

If you are using Android Studio, the Device File Explorer tool, docked by default on the right, will let you browse the filesystem of your device.