[英]How to change fragment inside getItem of FragmentStatePagerAdapter
我有這段代碼,我想根據某些布爾值更改FragmentStatePageAdapter的第一個片段(在viewpager內部)。
inner class MainFragmentAdapter(fragmentManager: FragmentManager) :
FragmentStatePagerAdapter(fragmentManager) {
override fun getCount(): Int {
return MainView.Fragments.values().size
}
override fun getItem(position: Int): Fragment? {
return when (position) {
0 -> {
if (booleanOne && !booleanTwo) {
FragmentOne.newInstance()
} else if (booleanTwo && !booleanOne) {
FragmentTwo.newInstance()
} else {
FragmentThree.newInstance()
}
}
else -> null
}
}
}
到目前為止,我發現的唯一解決方案是,當我個人知道其中一個布爾值已更改時,我只是做了類似的事情:
_fragmentAdapter = MainFragmentAdapter(getLifecycleFragmentManager())
fragmentViewPager.adapter = _fragmentAdapter
因此,我只是再次設置了適配器,但是這樣做似乎不可行。 我不能強迫它再次計算getItem嗎?
在您的類中進行這些更改, notifyDataSetChanged()
然后重寫getItemPosition()
,它將在每次通知時調用,然后只返回各自的常量POSITION_NONE
如果您想查看新的更改),否則返回POSITION_UNCHANGED
inner class MainFragmentAdapter(fragmentManager: FragmentManager) :
FragmentStatePagerAdapter(fragmentManager) {
override fun getCount(): Int {
return MainView.Fragments.values().size
}
override fun getItem(position: Int): Fragment? {
return when (position) {
0 -> {
if (booleanOne && !booleanTwo) {
FragmentOne.newInstance()
} else if (booleanTwo && !booleanOne) {
FragmentTwo.newInstance()
} else {
FragmentThree.newInstance()
}
notifyDataSetChanged();
}
else -> null
}
}
override fun getItemPosition(@NonNull `object`: Any): Int {
// this method will be called for every fragment in the ViewPager
return if (`object` is FragmentOne) {
POSITION_UNCHANGED // don't force a reload
} else {
// POSITION_NONE means something like: this fragment is no longer valid
// triggering the ViewPager to re-build the instance of this fragment.
POSITION_NONE
}
}
}
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