android - ViewPager InstantiateItem() 返回错误的位置值

Question

我是 android 编程的初学者。我正在使用按钮 onclick 使用下面的代码将新页面添加到 viewpager。但是，在滑动 Activity 中实例化项目时，viewpager 返回错误的位置值。

向右滑动

正确位置:1、2、3(第2、3、4页)

改为返回错误的位置:2、3、4

向左滑动

正确位置:3、2、1(第 4、3、2 页)

改为返回错误的位置:2、1、0

我想从 instantiateItem() 获取位置值，以从“views”数组列表的特定位置获取 View ，以显示在 viewpager 上。错误的位置会导致显示错误的 View 。希望可以有人帮帮我!!!提前致谢。

添加按钮:

findViewById(R.id.btnAdd).setOnClickListener(new OnClickListener() {    
            @Override
            public void onClick(View v) {
                LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                View itemView = inflater.inflate(R.layout.image_text_1, null);

                // the array list
                views.add(itemView);

                pagerAdapter.notifyDataSetChanged();

            }
        });

ViewPager:

private class SlideAdapter extends PagerAdapter {
              ArrayList<View> views = new ArrayList<View>();

              @Override
              public int getItemPosition (Object object)
              {
                  int index = views.indexOf((View)object);
                  if(views.contains((View)object)){
                      return index;
                  }else{
                      return POSITION_NONE;
                  }     
              }

              @Override
              public Object instantiateItem (ViewGroup container, final int position)
              {
                    //for example, when I swipe to the right from page 1 to page 2, the int position return value of 2 instead of 1.
                    View v = views.get(position);

                    imagePage = (ImageView) v.findViewById(R.id.imgSlide);
                    imagePage.setOnLongClickListener(null);
                    imagePage.setLongClickable(true);
                    imagePage.setOnLongClickListener(btnImageChoose);
                    ((ViewPager)container).addView(v, 0);
                    return v;
              }

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

              @Override
              public int getCount ()
              { 
                  return views.size();
              }

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

              public int addView (View v)
              {
                return addView (v, views.size());
              }

              public int addView (View v, int position)
              {
                views.add (position, v);
                return position;
              }

              public int removeView (ViewPager pager, View v)
              {
                return removeView (pager, views.indexOf (v));
              }

              public int removeView (ViewPager pager, int position)
              {
                pager.setAdapter (null);
                views.remove (position);
                pager.setAdapter (this);

                return position;
              }

              public View getView (int position)
              {
                return views.get (position);
              }

            }

Answer 1

似乎不是 instantiateItem() 的问题。我从 setPrimaryItem() 获取当前 View 。

private View mCurrentView;

@Override
public void setPrimaryItem(ViewGroup container, int position, Object object) {
    mCurrentView = (View)object;
}