activity与fragment交叉生命周期
与https://blog.csdn.net/u010513497/article/details/50961042结果一致。
与https://blog.csdn.net/shuijianbaozi/article/details/52994525不一致，可能是设置fragment的方式不一样。
待解决的疑问：什么情况下fragment调用onInflate()
Fragment生命周期
①Activity加载Fragment的时候,依次调用下面的方法: onAttach -> onCreate -> onCreateView -> onActivityCreated -> onStart ->onResume ②当我们弄出一个悬浮的对话框风格的Activity,或者其他,就是让Fragment所在的Activity可见,但不获得焦点 onPause ③当对话框关闭,Activity又获得了焦点: onResume ④当我们替换Fragment,并调用addToBackStack()将他添加到Back栈中 onPause -> onStop -> onDestoryView ！！注意,此时的Fragment还没有被销毁哦!!! ⑤当我们按下键盘的回退键，Fragment会再次显示出来: onCreateView -> onActivityCreated -> onStart -> onResume ⑥如果我们替换后,在事务commit之前没有调用addToBackStack()方法将 Fragment添加到back栈中的话;又或者退出了Activity的话,那么Fragment将会被完全结束, Fragment会进入销毁状态 onPause -> onStop -> onDestoryView -> onDestory -> onDetach
只有一个activity
有可以通过底部的三个tab切换不同的fragment
第一次进入APP
2022-02-16 22:10:07.603 26756-26756/com.example.bottomnavigationactivityapp I/MyMainActivity: onCreate: 2022-02-16 22:10:07.726 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onAttach: 2022-02-16 22:10:07.726 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onCreate: 2022-02-16 22:10:07.726 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onCreateView: 2022-02-16 22:10:07.729 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onActivityCreated: 2022-02-16 22:10:07.729 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onViewStateRestored: 2022-02-16 22:10:07.732 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onStart: 2022-02-16 22:10:07.733 26756-26756/com.example.bottomnavigationactivityapp I/MyMainActivity: onStart 2022-02-16 22:10:07.737 26756-26756/com.example.bottomnavigationactivityapp I/MyMainActivity: onResume 2022-02-16 22:10:07.738 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onResume: home 2022-02-16 22:10:32.210 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onPause: 2022-02-16 22:10:32.210 26756-26756/com.example.bottomnavigationactivityapp I/MyMainActivity: onPause 2022-02-16 22:10:32.248 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onStop: 2022-02-16 22:10:32.248 26756-26756/com.example.bottomnavigationactivityapp I/MyMainActivity: onStop: 2022-02-16 22:10:32.255 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onSaveInstanceState: 在stop后调用 重新点开（此时程序未退出） 2022-02-16 22:10:48.743 26756-26756/com.example.bottomnavigationactivityapp I/MyMainActivity: onRestart: 2022-02-16 22:10:48.745 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onStart: 2022-02-16 22:10:48.746 26756-26756/com.example.bottomnavigationactivityapp I/MyMainActivity: onStart 2022-02-16 22:10:48.747 26756-26756/com.example.bottomnavigationactivityapp I/MyMainActivity: onResume 2022-02-16 22:10:48.748 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onResume: 切换第二个fragment 2022-02-16 22:11:31.134 26756-26756/com.example.bottomnavigationactivityapp I/My------Dashboard------Fragment: onAttach: 2022-02-16 22:11:31.134 26756-26756/com.example.bottomnavigationactivityapp I/My------Dashboard------Fragment: onCreate: 2022-02-16 22:11:31.139 26756-26756/com.example.bottomnavigationactivityapp I/My------Dashboard------Fragment: onActivityCreated: 2022-02-16 22:11:31.140 26756-26756/com.example.bottomnavigationactivityapp I/My------Dashboard------Fragment: onViewStateRestored: 2022-02-16 22:11:31.140 26756-26756/com.example.bottomnavigationactivityapp I/My------Dashboard------Fragment: onStart: 2022-02-16 22:11:31.140 26756-26756/com.example.bottomnavigationactivityapp I/My------Dashboard------Fragment: onResume: 2022-02-16 22:11:31.142 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onPause: 2022-02-16 22:11:31.142 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onStop: 2022-02-16 22:11:31.283 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onDestroyView: 点击第一个fragment导航栏对应的TAb，创建了新的homefragment。Tag1="从第二个fragment点击第一个fragment对应的TAB，此时创建了新的homefragment"
tab2022-02-16 22:11:56.795 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onAttach: 2022-02-16 22:11:56.795 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onCreate: 2022-02-16 22:11:56.796 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onCreateView: 2022-02-16 22:11:56.799 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onActivityCreated: 2022-02-16 22:11:56.799 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onViewStateRestored: 2022-02-16 22:11:56.799 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onStart: 2022-02-16 22:11:56.800 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onResume: 2022-02-16 22:11:56.801 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onDestroy: 这应该是上一个homefragment 2022-02-16 22:11:56.801 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onDetach: 这应该是上一个homefragment 2022-02-16 22:11:56.801 26756-26756/com.example.bottomnavigationactivityapp I/My------Dashboard------Fragment: onPause: 2022-02-16 22:11:56.801 26756-26756/com.example.bottomnavigationactivityapp I/My------Dashboard------Fragment: onStop: 2022-02-16 22:11:56.953 26756-26756/com.example.bottomnavigationactivityapp I/My------Dashboard------Fragment: onDestroyView: 2022-02-16 22:11:56.953 26756-26756/com.example.bottomnavigationactivityapp I/My------Dashboard------Fragment: onDestroy: 2022-02-16 22:11:56.953 26756-26756/com.example.bottomnavigationactivityapp I/My------Dashboard------Fragment: onDetach:
点击返回按钮：退出了APP
2022-02-16 22:15:13.693 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onPause:
2022-02-16 22:15:13.693 26756-26756/com.example.bottomnavigationactivityapp I/MyMainActivity: onPause
2022-02-16 22:15:14.204 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onStop:
2022-02-16 22:15:14.205 26756-26756/com.example.bottomnavigationactivityapp I/MyMainActivity: onStop:
2022-02-16 22:15:14.218 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onDestroyView:
2022-02-16 22:15:14.219 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onDestroy:
2022-02-16 22:15:14.219 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onDetach:
2022-02-16 22:15:14.220 26756-26756/com.example.bottomnavigationactivityapp I/MyMainActivity: onDestroy:
再次进入app（与第一次进入app相同）
2022-02-16 22:16:35.872 26756-26756/com.example.bottomnavigationactivityapp I/MyMainActivity: onCreate:
2022-02-16 22:16:35.920 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onAttach:
2022-02-16 22:16:35.921 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onCreate:
2022-02-16 22:16:35.921 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onCreateView:
2022-02-16 22:16:35.923 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onActivityCreated:
2022-02-16 22:16:35.923 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onViewStateRestored:
2022-02-16 22:16:35.924 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onStart:
2022-02-16 22:16:35.924 26756-26756/com.example.bottomnavigationactivityapp I/MyMainActivity: onStart
2022-02-16 22:16:35.925 26756-26756/com.example.bottomnavigationactivityapp I/MyMainActivity: onResume
2022-02-16 22:16:35.926 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onResume:
点击第二个fragment
2022-02-16 22:17:08.680 26756-26756/com.example.bottomnavigationactivityapp I/My------Dashboard------Fragment: onAttach:
2022-02-16 22:17:08.680 26756-26756/com.example.bottomnavigationactivityapp I/My------Dashboard------Fragment: onCreate:
2022-02-16 22:17:08.684 26756-26756/com.example.bottomnavigationactivityapp I/My------Dashboard------Fragment: onActivityCreated:
2022-02-16 22:17:08.684 26756-26756/com.example.bottomnavigationactivityapp I/My------Dashboard------Fragment: onViewStateRestored:
2022-02-16 22:17:08.684 26756-26756/com.example.bottomnavigationactivityapp I/My------Dashboard------Fragment: onStart:
2022-02-16 22:17:08.685 26756-26756/com.example.bottomnavigationactivityapp I/My------Dashboard------Fragment: onResume:
2022-02-16 22:17:08.686 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onPause:
2022-02-16 22:17:08.686 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onStop:
2022-02-16 22:17:08.835 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onDestroyView:
点击返回，返回了先前的fragment。注意与这儿与tag1出的操作不同，没有生成新的homefragment。
2022-02-16 22:18:01.121 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onCreateView:
2022-02-16 22:18:01.125 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onActivityCreated:
2022-02-16 22:18:01.126 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onViewStateRestored:
2022-02-16 22:18:01.126 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onStart:
2022-02-16 22:18:01.126 26756-26756/com.example.bottomnavigationactivityapp I/My------Home------Fragment: onResume:
2022-02-16 22:18:01.127 26756-26756/com.example.bottomnavigationactivityapp I/My------Dashboard------Fragment: onPause:
2022-02-16 22:18:01.127 26756-26756/com.example.bottomnavigationactivityapp I/My------Dashboard------Fragment: onStop:
2022-02-16 22:18:01.307 26756-26756/com.example.bottomnavigationactivityapp I/My------Dashboard------Fragment: onDestroyView:
2022-02-16 22:18:01.308 26756-26756/com.example.bottomnavigationactivityapp I/My------Dashboard------Fragment: onDestroy:
2022-02-16 22:18:01.308 26756-26756/com.example.bottomnavigationactivityapp I/My------Dashboard------Fragment: onDetach:
Activity生命周期
异常生命周期下数据的onSaveInstanceState的使用
onSaveIntanceState方法和onRestoreInstanceState方法是成对出现的，在正常的生命周期下是不会被调用的，除非在异常生命周期下会被调用用来保存和恢复数据。
异常生命生命周期下常见有两种，分贝为资源相关的系统配置发生改变时（如横竖屏切换时显示不同的图片资源）和系统资源不足回收低优先级的Activity导致的Activity重建。
实现过程为当Activity发生异常时，Activity调用onSaveInstanceState方法中使用Bundle存储数据，然后Activity会委托Window去保存数据，接着window委托父类继续保存数据，顶层为ViewGroup,到达顶层后然后再去通知各个子View去保存数据。onSaveInstanceState调用发生在onStop方法之前，和onPause方法没有前后之分，执行onDestory方法销毁当前的Activity，然后创建新的Activity，使用onCreate和onRestoreIntanceState方法去恢复数据。这两个都可以进行数据恢复，但是区别在于onRestoreIntanceState一旦调用的话其中的Bundle参数一定会有值，而onCreate不一定，在正常生命周期下的Bundle参数就是为空，此使用onCreate方法就进行判空处理，官方建议使用onRestoreIntanceState进行处理数据恢复。
当系统资源不足时，系统会按照低优先级回收Activity,这种情况下也会触发onSaveInstanceState方法的进行数据保存以及onRestoreIntanceState方法进行数据恢复。回收优先级分为三种后台、可见但非前台等级。
总而言之，系统只有在Activity异常终止的情况下调用onSaveInstanceState和onRestoreIntanceState进行数据保存与恢复。其他情况下不会调用。
在fragment的构造方法获取不到相应activity的taskId，可能是这个时候activity还没有创建好。并没有对应的taskId
