如何强制 ViewPager 重新实例化其项目 [英] How to force ViewPager to re-instantiate its items

问题描述

我正在使用 ViewPager 允许用户在其视图之间滑动.有没有办法强制此 ViewPager 重新加载/重新实例化其视图，以防它们不再有效或需要刷新?我试图在其适配器上调用 notifyDataSetChanged() 但这不会再次调用 instantiateItem() 方法.

I am using ViewPager to allow user to swipe between its views. Is there a way how to force this ViewPager to reload/re-instantiate its views in case that they are no longer valid or needs to be refreshed? I tried to call notifyDataSetChanged() on its adapter but this does not invoke instantiateItem() method again.

这是从 ViewPager 及其适配器定义扩展而来的类.Bellow 是我想强制刷新项目时调用的 refresh() 方法.

Here is the class that extends from ViewPager and its adapter definision. Bellow is the refresh() method that I call when I want to force to refresh items.

public class DayFlipper extends ViewPager {

public class FlipperAdapter extends PagerAdapter {

    @Override
    public int getCount() {
        return DayFlipper.DAY_HISTORY;
    }

    @Override
    public void startUpdate(View container) {
    }

    @Override
    public Object instantiateItem(View container, int position) {
        Log.d(TAG, "instantiateItem(): " + position);

        Date d = DateHelper.getBot();
        for (int i = 0; i < position; i++) {
            d = DateHelper.getTomorrow(d);
        }

        d = DateHelper.normalize(d);

        CubbiesView cv = new CubbiesView(mContext);
        cv.setLifeDate(d);
        ((ViewPager) container).addView(cv, 0);
        // add map
        cv.setCubbieMap(mMap);
        cv.initEntries(d);
        return cv;
    }

    @Override
    public void destroyItem(View container, int position, Object object) {
        ((ViewPager) container).removeView((CubbiesView) object);
    }

    @Override
    public void finishUpdate(View container) {

    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        return view == ((CubbiesView) object);
    }

    @Override
    public Parcelable saveState() {
        return null;
    }

    @Override
    public void restoreState(Parcelable state, ClassLoader loader) {

    }

}

    ...

    public void refresh() {
    getAdapter().notifyDataSetChanged();
}
}

推荐答案

我找到了解决方案.这只是我的问题的一种解决方法，但目前是唯一的解决方案.

I have found a solution. It is just a workaround to my problem but currently the only solution.

ViewPager PagerAdapter 不更新视图

public int getItemPosition(Object object) {
   return POSITION_NONE;
}

有人知道这是否是一个错误吗?

Does anyone know whether this is a bug or not?

这篇关于如何强制 ViewPager 重新实例化其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！