findFragmentById

findFragmentById is a method commonly found in Android development frameworks, specifically within the FragmentManager class. Its primary purpose is to locate and retrieve a Fragment instance that has been previously added to the activity or another fragment, identified by a unique integer ID.

When you add a Fragment to your activity's layout, either statically in XML or dynamically through code, you typically assign it an ID. This ID acts as a key, allowing you to later reference and interact with that specific Fragment. The findFragmentById method uses this assigned ID to search through the fragments currently managed by the FragmentManager.

If a Fragment with the specified ID is found, the method returns a reference to that Fragment object. This allows you to then call methods on the Fragment, such as accessing its views, calling its public methods, or manipulating its state. If no Fragment is found with the given ID, the method returns null. This is a crucial method for managing the lifecycle and interaction of Fragments within an Android application, enabling dynamic UI updates and complex fragment-based navigation.