Fix arrivals onBackPressed() on Android 13+

[robertgodfrey]

Problem

Pressing back while viewing a stop's arrivals exited the app instead of dismissing the panel and returning to the map.

Root cause

HomeActivity overrode onBackPressed() to handle panel dismissal, but this override was silently bypassed on Android 13+ (API 33+). Modern Android routes back presses through WindowOnBackInvokedDispatcher → AndroidX OnBackPressedDispatcher, whose fallback calls ComponentActivity.super.onBackPressed() directly — skipping subclass overrides entirely. The app has used androidx.activity:activity-ktx:1.9.3 for about 2 years, which made this the behavior on all currently-supported devices.

Fix

Migrate the back press logic from onBackPressed() into an OnBackPressedCallback registered with getOnBackPressedDispatcher() in onCreate(). This is the API that both the AndroidX dispatcher and the OS-level OnBackInvokedDispatcher actually invoke, and it works correctly on all API levels (not just 13+).

Behavior

• Panel expanded/anchored → collapse to header
• Panel collapsed → dismiss arrivals, return to map
• No panel showing → exit as before

Before:

before.mp4

After:

after.mp4

• Apply the AndroidStyle.xml style template to your code in Android Studio.

• Run the unit tests with gradlew connectedObaGoogleDebugAndroidTest to make sure you didn't break anything

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Summary by CodeRabbit

• Chores
  • Updated back button navigation handling to use modern Android framework patterns.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 1be213d6-965b-4fc6-8194-46f12be5d246

📥 Commits

Reviewing files that changed from the base of the PR and between e65872a and 47b34a8.

📒 Files selected for processing (1)

• onebusaway-android/src/main/java/org/onebusaway/android/ui/HomeActivity.java

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📝 Walkthrough

Walkthrough

HomeActivity migrates system back press handling from the deprecated onBackPressed() override to the modern OnBackPressedDispatcher callback pattern. The sliding panel collapse and map focus clear logic is preserved in the callback registered during onCreate().

Changes

Back Press Handling Migration

Layer / File(s)	Summary
Migrate to OnBackPressedDispatcher onebusaway-android/src/main/java/org/onebusaway/android/ui/HomeActivity.java	Import OnBackPressedCallback, register a callback in onCreate() to intercept back presses and collapse the sliding panel when expanded/anchored or clear map focus when collapsed, then remove the deprecated onBackPressed() override. Behavior remains identical.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely summarizes the main change: fixing the back button behavior on Android 13+ by moving from onBackPressed() override to OnBackPressedDispatcher callback.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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[aaronbrethorst]

Rob, this is a really nicely scoped fix. The root-cause writeup in the PR description is genuinely illuminating — pinning the silent bypass on WindowOnBackInvokedDispatcher → OnBackPressedDispatcher → ComponentActivity.super.onBackPressed() skipping subclass overrides is exactly the kind of explanation that makes a one-file diff easy to land with confidence. The Before/After videos are also a great touch.

I cross-checked the migration against the official Android docs (Provide custom back navigation; Add support for the predictive back gesture) and the implementation matches the documented pattern step-for-step.

Critical Issues (0 found)

None.

Important Issues (0 found)

None.

Suggestions (1 found)

• The fallback inside handleOnBackPressed() uses the documented setEnabled(false); getOnBackPressedDispatcher().onBackPressed(); pattern, which permanently disables the callback after first fallback [HomeActivity.java:428-429]. In practice this is fine for HomeActivity because the only time the fallback runs is when no panel is showing and the activity is about to finish, so the disabled state never matters. Worth being aware of as a subtle behavior of this idiom, but no change needed here.

Follow-up (out of scope, tracked separately)

The same Android 13+ bug almost certainly affects two other activities still using the deprecated onBackPressed() override:

• TripPlanActivity.java:261-267 — has panel-collapse logic structurally identical to the bug fixed here.
• InfrastructureIssueActivity.java:722-726 — its post-back spinner reset is being silently skipped on API 33+.

I've opened #1566 to track these migrations so they don't get lost.

thanks for knocking this out!