Fix #2075: Fix ViewModel not clearing on NavigationState pop (nav3)

[ArpitDhoundiyal]

This PR fixes issue [#2075]
where ViewModel.onCleared() was not being called when a screen was popped from the navigation stack, and only triggered when the app was fully closed.

Previously, with nav3 NavigationState, ViewModel.onCleared()
was not being triggered when a NavEntry was removed from the stack.

This was happening because ViewModelStore was not being cleared on pop.
Added rememberViewModelStoreNavEntryDecorator with
removeViewModelStoreOnPop = { true } to ensure that
ViewModelStore is cleared when the entry is removed.

Verified via logs that onCleared() is now properly invoked
when navigating away from the screen.

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a critical memory management issue within the navigation system by ensuring that ViewModel.onCleared() is reliably invoked when a screen is removed from the navigation stack. This prevents potential resource leaks and improves the overall stability and resource utilization of the application. The fix involves a specific configuration change to the navigation state decorators, alongside routine dependency updates.

Highlights

• ViewModel Lifecycle Fix: Resolved an issue where ViewModel.onCleared() was not being called when a screen was popped from the navigation stack, leading to potential memory leaks.
• Navigation State Configuration: Configured rememberViewModelStoreNavEntryDecorator with removeViewModelStoreOnPop = { true } to ensure the ViewModelStore is properly cleared upon navigation entry removal.
• Dependency Updates: Updated the Android Gradle Plugin and Android Tools versions to 9.0.1 and 32.0.1 respectively.

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Changelog

• core/navigation/src/main/kotlin/com/google/samples/apps/nowinandroid/core/navigation/NavigationState.kt
  • Enabled removeViewModelStoreOnPop for rememberViewModelStoreNavEntryDecorator to ensure ViewModelStore clearing on navigation pop.
• feature/topic/impl/src/main/kotlin/com/google/samples/apps/nowinandroid/feature/topic/impl/TopicViewModel.kt
  • Added an unused android.util.Log import.
  • Introduced minor whitespace changes.
• gradle/libs.versions.toml
  • Upgraded androidGradlePlugin from 9.0.0 to 9.0.1.
  • Upgraded androidTools from 32.0.0 to 32.0.1.

Activity

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[gemini-code-assist]

Code Review

This pull request correctly addresses an issue where ViewModels were not being cleared when a screen was popped from the navigation stack. The fix, which involves setting removeViewModelStoreOnPop = { true } in rememberViewModelStoreNavEntryDecorator, is appropriate and directly solves the problem described. The PR also includes some dependency updates and formatting changes. I've identified one minor issue regarding an unused import that should be removed.

[gemini-code-assist]

This Log import is unused within the file and should be removed to maintain code cleanliness. It was likely added for debugging during development and is no longer needed.