Get boolean from database using Android and SQLite

java

prompt-engineering

best-practices

dataframe

byNikita Barsukov·Dec 27, 2024

When you need to retrieve a boolean from an SQLite database in Android, you need to remember that it is stored as an integer (0 or 1). Use a Cursor to fetch the integer and convert it into a boolean:

// Oh look, someone left a query at our door. Let's pick it up.
Cursor cursor = database.query("myTable", new String[]{"myBooleanColumn"}, null, null, null, null, null);
// If the query returns an eerie 1, then Ghost in the Shell must be real!
boolean myBoolean = cursor.moveToFirst() && cursor.getInt(0) == 1;
cursor.close();

Here, myTable and myBooleanColumn are placeholders for your table and boolean column respectively. The query function is called to fetch the column and getInt is used to convert the first column of the cursor row into a boolean.

Fetching booleans stored as strings

If the booleans are stored as strings, use this piece of magic:

// It's "true" I swear! getString promises to return a boolean, as long as it doesn't forget its glasses.
boolean myBoolean = "true".equalsIgnoreCase(cursor.getString(boolean_column_index));

Here, equalsIgnoreCase is used with caution to handle any case variations in the database values while storing booleans.

Choosing the right method for the job

It’s prime time to remember that SQLite doesn't natively support boolean types. Hence, we deal with booleans as either integers (0/1) or strings ("false"/"true"). So, you must match the method to the respective data type. Using getInt() for integer representation and getString() for string representation ensures smooth sailing in all circumstances.

Lay the golden rules for your booleans

Half the battle is won if you have a strategy for storing booleans. Here are some rules and recommendations to keep in mind:

Using integers to store booleans

Consistency: It’s a binary world, stick with 0 or 1.
Retrieval: With the truth table in mind, use cursor.getInt(boolean_column_index) == 1.

Using strings to store booleans

Consistency: Stick with the brotherhood of lowercase or the aristocracy of uppercase when storing.
Retrieval: Drop cursor.getString(boolean_column_index).equalsIgnoreCase("true") into the magic hat and ... voilà!

Preventing conflicts

Confusion: No mix and matching of 0 and "false", 1 and "true".
Solution: Stick to one method, and if change is the only constant, then have a migration plan.