android - 如何获取 ViewPager 当前 View ，这是在 onPageSelected 中向用户显示的 View

Question

我用这种方式获取ViewPager的当前View:

private class OuterAdapter extends PagerAdapter{

    private SwipingVideoPage currentPage;

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        SwipingVideoPage page = new SwipingVideoPage();
        container.addView(page);
        return page;
    }

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

    @Override
    public void setPrimaryItem(ViewGroup container, int position, Object object) {
        currentPage = (SwipingVideoPage)object;
        super.setPrimaryItem(container, position, object);
    }

    public SwipingVideoPage getCurrenPage() {
        return currentPage;
    }
}

我想我可以调用 ViewPager.getAdapter.getCurrentPage() 来获取当前 View 。但我发现它在 ViewPager.OnPageChangeListener.onPageSelected() 中不起作用:

private class OuterChangeListener implements ViewPager.OnPageChangeListener {

    @Override
    public void onPageSelected(int position) {
        ((OuterAdapter)outerViewPager.getAdapter()).getCurrenPage()  //this returns the previous shown view, not the right one
    }
}

也许 onPageSelected() 在 setPrimaryItem() 之前被调用，这是正确的吗？

以及如何在onPageSelected() 中获取ViewPage 的主视图？

Answer 1

正如@Mohammad Fareed所说，我没有在ViewPager中找到直接获取当前页面的方法。

所以我用这种方式来解决问题:

private Map<Integer, View> pageMap;     //records all the pages in the ViewPager
private SwipingVideoPage currentPage;

private class OuterAdapter extends PagerAdapter{

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        SwipingVideoPage page = new SwipingVideoPage();
        container.addView(page);
        pageMap.put(position, page);    //add page
        return page;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        container.removeView((View)object);
        pageMap.remove(position);      //remove page which is removed from ViewPager
    }
}

private class OuterChangeListener extends ViewPager.SimpleOnPageChangeListener {

    @Override
    public void onPageSelected(int position) {
        currentPage = pageMap.get(position);    //get current page
    }
}

我在我的项目中使用了这些代码，到目前为止效果很好。