What is the difference between using commit and commitNow in the context of transactions and database operations?

In Android, when working with fragment transactions or databases, the methods commit and commitNow differ in execution time:

• commit() — puts the transaction in a queue for execution. It will be executed asynchronously in the future, usually in the next message processing cycle. This helps avoid blocking the UI thread.

• commitNow() — executes the transaction immediately, synchronously. This means all transaction operations will be completed before returning from the method.

Example with FragmentTransaction:

supportFragmentManager.beginTransaction()
    .replace(R.id.container, MyFragment())
    .commit() // Asynchronous

supportFragmentManager.beginTransaction()
    .replace(R.id.container, MyFragment())
    .commitNow() // Synchronous

Using commitNow is useful when you need to immediately get the result of the transaction, for example, to work with the added fragment right away. However, commitNow cannot be used if the transaction is added to the back stack.

In the context of databases (e.g., SQLite), commit usually means confirming the transaction changes, but in Android API for working with transactions, the concepts of beginTransaction(), setTransactionSuccessful(), and endTransaction() are more commonly used.