onCreate
onStart
onResume
onPause
onStop
onDestroy
当Activity在异常情况下终止时: onSaveInstanceState onRestoreInstanceState
横竖屏切换的生命周期：onPause() --> onSaveInstanceState() --> onStop() --> onDestory() --> onCreate() --> onStart() --> onRestoreInstanceState() --> onResume()
singleInstancePerTask(android 12)
onNewIntent
int FLAG_ACTIVITY_BROUGHT_TO_FRONT
This flag is not normally set by application code, but set for you by the system as described in the launchMode documentation for the singleTask mode. int FLAG_ACTIVITY_CLEAR_TASK
If set in an Intent passed to Context.startActivity(), this flag will cause any existing task that would be associated with the activity to be cleared before the activity is started. int FLAG_ACTIVITY_CLEAR_TOP
If set, and the activity being launched is already running in the current task, then instead of launching a new instance of that activity, all of the other activities on top of it will be closed and this Intent will be delivered to the (now on top) old activity as a new Intent. int FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET
This constant was deprecated in API level 21. As of API 21 this performs identically to FLAG_ACTIVITY_NEW_DOCUMENT which should be used instead of this. int FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS
If set, the new activity is not kept in the list of recently launched activities. int FLAG_ACTIVITY_FORWARD_RESULT
If set and this intent is being used to launch a new activity from an existing one, then the reply target of the existing activity will be transferred to the new activity. int FLAG_ACTIVITY_LAUNCHED_FROM_HISTORY
This flag is not normally set by application code, but set for you by the system if this activity is being launched from history. int FLAG_ACTIVITY_LAUNCH_ADJACENT
This flag is only used for split-screen multi-window mode. int FLAG_ACTIVITY_MATCH_EXTERNAL
If set in an Intent passed to Context.startActivity(), this flag will attempt to launch an instant app if no full app on the device can already handle the intent. int FLAG_ACTIVITY_MULTIPLE_TASK
This flag is used to create a new task and launch an activity into it. int FLAG_ACTIVITY_NEW_DOCUMENT
This flag is used to open a document into a new task rooted at the activity launched by this Intent. int FLAG_ACTIVITY_NEW_TASK
If set, this activity will become the start of a new task on this history stack. int FLAG_ACTIVITY_NO_ANIMATION
If set in an Intent passed to Context.startActivity(), this flag will prevent the system from applying an activity transition animation to go to the next activity state. int FLAG_ACTIVITY_NO_HISTORY
If set, the new activity is not kept in the history stack. int FLAG_ACTIVITY_NO_USER_ACTION
If set, this flag will prevent the normal Activity.onUserLeaveHint() callback from occurring on the current frontmost activity before it is paused as the newly-started activity is brought to the front. int FLAG_ACTIVITY_PREVIOUS_IS_TOP
If set and this intent is being used to launch a new activity from an existing one, the current activity will not be counted as the top activity for deciding whether the new intent should be delivered to the top instead of starting a new one. int FLAG_ACTIVITY_REORDER_TO_FRONT
If set in an Intent passed to Context.startActivity(), this flag will cause the launched activity to be brought to the front of its task’s history stack if it is already running. int FLAG_ACTIVITY_REQUIRE_DEFAULT
If set in an intent passed to Context.startActivity(), this flag will only launch the intent if it resolves to a single result. int FLAG_ACTIVITY_REQUIRE_NON_BROWSER
If set in an intent passed to Context.startActivity(), this flag will only launch the intent if it resolves to a result that is not a browser. int FLAG_ACTIVITY_RESET_TASK_IF_NEEDED
If set, and this activity is either being started in a new task or bringing to the top an existing task, then it will be launched as the front door of the task. int FLAG_ACTIVITY_RETAIN_IN_RECENTS
By default a document created by FLAG_ACTIVITY_NEW_DOCUMENT will have its entry in recent tasks removed when the user closes it (with back or however else it may finish()). int FLAG_ACTIVITY_SINGLE_TOP
If set, the activity will not be launched if it is already running at the top of the history stack. int FLAG_ACTIVITY_TASK_ON_HOME
If set in an Intent passed to Context.startActivity(), this flag will cause a newly launching task to be placed on top of the current home activity task (if there is one).
一个任务是用户作业的一个堆栈, 堆栈中保存Activity实例