托管ViewPager活动上的片段生命周期

I have two fragments on an activity hosting them, by a ViewPager. When I update Fragment A's data , it doesn't on the display. So I figured I should play with the lifecycle...I placed locates at all of the lifecycle callbacks and none were invoked when I was sliding through the fragments. Don't the fragments change though the lifecycle when you slide between them? So how do you refresh their content ?I have two fragments on an activity hosting the