Fragment visibility judgment

1. Fragment is used between activities:
This situation is the simplest, because the life cycle of the fragment at this time is consistent with the life cycle of the activity.When there is another activity, as long as you monitor the onResume and onPause methods of Fragment, you can judge whether it is displayed or hidden (as for the meaning of these two methods, I will not say more, if you don’t understand, go to the life cycle of activity and fragment by yourself)

@Overridepublic void onResume() {super.onResume();}@Overridepublic void onPause() {super.onPause();}

2. Fragment in ViewPager
The onResume() and onPause() methods will not be called when the Fragment in ViewPager is switched left and right.Because these two methods follow the life cycle of the activity, at this time we can reset the setUserVisibleHint(boolean isVisibleToUser) method in the fragment to monitor whether the Fragment is visible

@Overridepublic voidsetUserVisibleHint(booleanisVisibleToUser) {super.setUserVisibleHint(isVisibleToUser);if(isVisibleToUser){//visible}else{//Invisible}}

3. Use the show() and hide() methods to display and hide fragments
In this case, the fragment is switched to another fragment in an activity, then the above two monitors you willIt is useless to find it. At this time, we can listen to the onHiddenChanged(boolean hidden) method to determine whether it is visible to the user.

@Overridepublic void onHiddenChanged(booleanhidden) {super.onHiddenChanged(hidden);if(hidden){//Invisible}else{//visible}}