android runtime_error ai_generated true

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example/com.example.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object android.os.Bundle.getSerializable(java.lang.String)' on a null object reference

ID: android/activity-recreated-savedinstancestate-null

Also available as: JSON · Markdown · 中文
92%Fix Rate
89%Confidence
1Evidence
2023-12-01First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
Android 11 (API 30) active — — —
Android 14 (API 34) active — — —
AndroidX Activity 1.8.0 active — — —

Root Cause

Activity is recreated (e.g., after rotation or process death) and `savedInstanceState` is null, but the code attempts to retrieve a serializable object from the bundle without null check.

generic

中文

活动被重新创建（例如，旋转或进程终止后），`savedInstanceState` 为 null，但代码尝试从 bundle 中检索可序列化对象而没有进行空检查。

Official Documentation

https://developer.android.com/guide/components/activities/activity-lifecycle#saving-state

Workarounds

  1. 95% success Add a null check before accessing the bundle: `if (savedInstanceState != null) { val data = savedInstanceState.getSerializable("key") }` 
    Add a null check before accessing the bundle: `if (savedInstanceState != null) { val data = savedInstanceState.getSerializable("key") }`
  2. 90% success Use `onSaveInstanceState` to persist data and `onRestoreInstanceState` to restore it safely with null checks: `override fun onRestoreInstanceState(savedInstanceState: Bundle) { super.onRestoreInstanceState(savedInstanceState); if (savedInstanceState.containsKey("key")) { val data = savedInstanceState.getSerializable("key") } }` 
    Use `onSaveInstanceState` to persist data and `onRestoreInstanceState` to restore it safely with null checks: `override fun onRestoreInstanceState(savedInstanceState: Bundle) { super.onRestoreInstanceState(savedInstanceState); if (savedInstanceState.containsKey("key")) { val data = savedInstanceState.getSerializable("key") } }`

中文步骤

  1. Add a null check before accessing the bundle: `if (savedInstanceState != null) { val data = savedInstanceState.getSerializable("key") }`
  2. Use `onSaveInstanceState` to persist data and `onRestoreInstanceState` to restore it safely with null checks: `override fun onRestoreInstanceState(savedInstanceState: Bundle) { super.onRestoreInstanceState(savedInstanceState); if (savedInstanceState.containsKey("key")) { val data = savedInstanceState.getSerializable("key") } }`

Dead Ends

Common approaches that don't work:

  1. 70% fail

    This only prevents recreation due to orientation changes, not process death or other configuration changes (e.g., locale). The NPE still occurs in other scenarios.

  2. 90% fail

    Calling super.onCreate() is already standard practice; the NPE occurs because `savedInstanceState` itself is null, not because it's accessed before super call.