Check existence DB and table in Android

How to know if the database exists?

For this you need to know the path where you created the database, and use this method, which tries the connection to determine if it actually exists:

private boolean checkDataBase(String Database_path) {
    SQLiteDatabase checkDB = null;
    try {
        checkDB = SQLiteDatabase.openDatabase(Database_path, null, SQLiteDatabase.OPEN_READONLY);
        checkDB.close();
    } catch (SQLiteException e) {
        Log.e("Error", "No existe la base de datos " + .getMessage());
    }
    return checkDB != null;
}

How to know if the table of a SQlite Database exists?

For that you can use this method which looks for the table record within the table sqlite_masterand checks if it exists by name:

public boolean isTableExists(String nombreTabla) {
    boolean isExist = false;
    Cursor cursor = db.rawQuery("select DISTINCT tbl_name from sqlite_master where tbl_name = '" + nombreTabla + "'", null);
    if (cursor != null) {
        if (cursor.getCount() > 0) {
            isExist = true;
        }
        cursor.close();
    }
    return isExist;
}