AAD Practice Questions

The Layout Inspector has a specific feature to track and display recomposition counts for each composable in real-time. By enabling this, a developer can interact with the app and see exactly which composables are recomposing and which are being skipped, making it the primary tool for diagnosing performance issues related to unnecessary recompositions.

The @Test annotation from the org.junit.Test package is used to mark a public function as a test case that the JUnit test runner should execute.

When Room detects a schema version mismatch and no migration path is provided, it will throw an IllegalStateException to prevent data corruption. The error message will explicitly state that a migration is missing. This is the default, safe behavior.

This correctly identifies the fundamental difference. LaunchedEffect is itself a composable and is used to run suspend functions in response to lifecycle events or state changes. rememberCoroutineScope is a hook that provides a CoroutineScope that can be used in non-composable contexts, like event handlers (onClick), to launch coroutines that are still scoped to the composition.

True. To improve system performance and battery life, Android 8.0 (API 26) placed significant restrictions on what apps can do in the background. One of these restrictions was that apps can no longer use their manifest to register a receiver for most implicit broadcasts (broadcasts not specifically targeted at the app). Apps must instead use Context.registerReceiver() to register a receiver at runtime, which is tied to the lifecycle of a component.

This is the correct and idiomatic way. You first add a Modifier.testTag("submit_button") to the Button composable in your app code. Then, in your test, you use the onNodeWithTag finder to locate the node and chain an assertion like assertIsDisplayed().

The @Entity annotation is used to mark a data class as a table in the Room database. Room will create a table based on the properties defined in this class.

State hoisting is a pattern of moving state up the composable tree to make child composables stateless. By doing this, the child composable (e.g., a single profile item) becomes dependent only on the inputs it receives. The state (like the 'like' status) is held by the parent, which can then decide to recompose only the specific child whose data has changed, rather than the entire list. This prevents unnecessary recompositions and improves performance.

conflate() is designed for this exact scenario. When the collector is busy and cannot process an emission, conflate ensures that intermediate values are dropped, but the most recent value is always buffered and delivered to the collector as soon as it's ready. This prevents the collector from being overwhelmed while guaranteeing the UI eventually reflects the latest state.

This constraint ensures the work will only run when the device is on an unmetered network, which is typically Wi-Fi. This correctly addresses one of the requirements.

This constraint defers the work until the device's battery is not considered low. This fulfills the requirement related to battery level.