片段在没有调用 onCreate 的情况下初始化

Question

So I have a fragment inside a viewpager which is contained inside a fragment which is getting initialize'd as shown in the debugger but doesn't have it's onCreate,onCreateView or any such methods being called. The activity containing has a bottom navigation view and contains 4 such fragments and this issue is only happening in 1 such fragment.

All these fragments and viewpagers and fragments inside them are created on the oncreate of the activity. If I move the logic to create the fragment to when a bottom tab is clicked, this issue gets solved on.

How is this possible ?

Answer 1

Only the currently active fragment and the two directly adjecant fragments are created when the viewpager is first shown. so the fragment for the first page, the fragment for the page shown if you "scroll to the left" and the fragment for the page shown when you "scroll to the right". the 4th fragment will be created when it is put in the next adjecant position.

so if you have fragments a,b,c,d in a viewpager like -a-[b]-cd- where b is the first visible page, only a,b and c will be created at startup. when you scroll to c -ab-[c]-d- onCreate for fragment d will be called.

Answer 2

You can control number of pages/fragments preloaded when you launch your activity by setting it's off Screen Page Limit on your view pager adapter. like this

• mViewPager.setOffScreenPageLimit(limit)

If you set limit to 0 than only first fragment would be load.

https://spotandroid.com/2016/11/23/android-tricks-viewpager-and-offscreen-tabs/

https://techcodegeek.wordpress.com/2015/06/23/android-viewpager-and-performance-improvements/

Answer 3

需要更多详细信息才能了解您的问题。您所提供的信息无法理解您面临的问题。