Interview guides / android

Corrupt draft cache: Android Interview Question

Corrupt draft cache interview question with a clear example answer for Android engineers. Practice with AceMobileInterview.

This is a common Android interview topic: Corrupt draft cache.

Below is a concise answer you can adapt in a real interview, then go deeper in the full AceMobileInterview track.

1. 1.Drafts vanish after process death; truncated JSON can crash on read. Fix atomicity and races (≈45–60 min).

   ## Scenario Draft JSON store is unsafe under kill + concurrent writes. ## How to investigate - Save rapidly while editing; force-stop app - Inspect filesDir draft file - Find `writeText` to final path + `!!` decode ## Planted bug 1: Non-atomic write **Symptom:** Truncated JSON **Root cause:** Direct write to destination **Fix:** Write temp + `renameTo` / `AtomicFile` ## Planted bug 2: Crash on bad JSON **Symptom:** Startup crash loop **Root cause:** Unchecked decode **Fix:** Catch; return empty draft; delete/quarantine bad file ## Planted bug 3: Concurrent read/write **Symptom:** Intermittent corruption **Root cause:** No mutex / single-thread executor around file access **Fix:** `Mutex` or single-thread dispatcher; debounce saves ## Optimization tips - `DataStore` is a strong modern answer—still explain atomicity underneath - Process death is normal; design for it ## What to say in the interview - How you reproduced partial writes - Why rename/AtomicFile matters