Android-ViewPager适配器，在实例化适配器之前设置主要项目 [英] Android - ViewPager Adapter, set primary item before adapter is instantiated

问题描述

我知道我能做到

 viewPager.setCurrentItem(position) 

将我的视图寻呼机设置在所需位置.我的问题是在实例化适配器之前是否以及如何执行此操作.

to set my view pager at the desired position. My question is if and how i can do this before the adapter is instantiated.

意思是，如果我这样做

pagerAdapter = new ViewPagerAdapter(arg1,arg2....);
viewPager.setAdapter(pagerAdapter);
viewPager.setCurrentItem(position);

首先构建项目0，然后再构建所需位置的项目.这花费了两倍的时间...在我的适配器中，每个项目都需要大量的工作来构建，因此，如果可能的话，最好避免构建0位置的项目.也许是通过在适配器的实例化处将所需位置作为参数传递的??

item 0 is first build and after that the item at the desired position is also build. Which takes double the time...In my adapter each item needs quite a lot of work to be build, so it would be best to avoid the 0 position item to be build if possible. Maybe by passing the desired position as an argument at the adapter's instantiation...?

有什么办法吗?

推荐答案

您可以通过调用onRestoreInstanceState来欺骗viewpager在设置适配器之前从给定位置开始，如下所示:

You can fool the viewpager to start at a given position before the adapter is set, by calling onRestoreInstanceState, like this:

int currentItem = 5;

Parcel parcel = Parcel.obtain();
writeParcelable(BaseSavedState.EMPTY_STATE, 0);

writeInt(currentItem);
writeParcelable(null, 0);

setDataPosition(0);
SavedState savedState = ViewPager.SavedState.CREATOR.createFromParcel(parcel);

mPager.onRestoreInstanceState(savedState);

mPager.setAdapter(mAdapter);

这篇关于Android-ViewPager适配器，在实例化适配器之前设置主要项目的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！