面试问题 activity生命周期，当设备旋转时android生命周期方法的调用顺序

来源：互联网发布：js attr方法编辑：程序博客网时间：2024/05/22 13:09

特别注意onSaveInstanceState并不是生命周期方法

当设备旋转时，通过Log可以看出：

设备销毁Activity实例：

01-05 20:07:11.289 7860-7860/? D/QuizActivity: onPause(Bundle) called01-05 20:07:11.290 7860-7860/? I/QuizActivity: onSaveInstanceState01-05 20:07:11.290 7860-7860/? D/QuizActivity: onStop(Bundle) called01-05 20:07:11.317 7860-7860/? D/QuizActivity: onDestroy(Bundle) called

重建Activity实例：

01-05 20:07:11.353 7860-7860/? D/QuizActivity: onCreate(Bundle) called01-05 20:07:11.373 7860-7860/? D/QuizActivity: onStart(Bundle) called01-05 20:07:11.377 7860-7860/? D/QuizActivity: onResume(Bundle)called

*继续深入

当我把setting->developer option->Don’t keep activities打开后再进行测试：

点击Back键

01-05 21:15:38.946 13590-13590/? D/QuizActivity: onPause(Bundle) called01-05 21:15:39.878 13590-13590/? D/QuizActivity: onStop(Bundle) called01-05 21:15:39.886 13590-13590/? D/QuizActivity: onDestroy(Bundle) called

发现onSaveInstanceState并没有被调用

点击Home键

01-05 21:17:43.975 13590-13590/? D/QuizActivity: onPause(Bundle) called01-05 21:17:44.723 13590-13590/? I/QuizActivity: onSaveInstanceState01-05 21:17:44.723 13590-13590/? D/QuizActivity: onStop(Bundle) called01-05 21:17:44.741 13590-13590/? D/QuizActivity: onDestroy(Bundle) called

当把Don’t keep activities选项关闭后再进行上述相同测试发现：

唯一不同的是点击Home键依次执行：

01-05 21:17:43.975 13590-13590/? D/QuizActivity: onPause(Bundle) called01-05 21:17:44.723 13590-13590/? I/QuizActivity: onSaveInstanceState01-05 21:17:44.723 13590-13590/? D/QuizActivity: onStop(Bundle) called

Activity没有被Destroy

而点击Back键，Activity都会被销毁（也不会保存activity的状态，即：不调用onSaveInstanceState）。可以理解为Back键相当于通知系统“用户不再需要当前的Activity”。

内容参考：Android编程权威指南

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