ViewPager InstantiateItem() Return 位置值错误

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，viewpager return 在滑动 activity 上实例化项目时位置值错误。

向右滑动

正确位置：1、2、3（第 2、3 和 4 页）

Return 错误的位置改为：2, 3, 4

向左滑动

正确位置：3、2、1（第 4、3 和 2 页）

Return 错误的位置改为：2, 1, 0

我想从 instantiateItem() 获取位置值，以便从 "views" 数组列表的特定位置获取视图，以显示在 viewpager 上。错误的位置会导致显示错误的视图。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

您不需要使用视图数组列表：

class SamplePagerAdapter extends PagerAdapter {

    // for example
    List<String> str = new ArrayList<String>();

    public SamplePagerAdapter(List<String> str){
          this.str = str;
    }

    private void addPage(String item) {
        str.add(item);
        notifyDataSetChanged();
    }

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

     @Override
     public View instantiateItem(ViewGroup container, int position) {
         LayoutInflater inflater = LayoutInflater.from(container.getContext());
         View v = inflater.inflate(R.layout.image_text_1, container, false);
         // Your code. (don't use addView);
         return v;
     }
}

并在 onClick 方法中：

public void OnClick(View v){
     adapter.addPage("New page")
}

Answer 2

好像不是instantiateItem()的问题。我从 setPrimaryItem() 获取当前视图。

private View mCurrentView;

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

ViewPager InstantiateItem() Return 位置值错误

ViewPager InstantiateItem() Return Wrong Value of Position

android

layout-inflater

android-viewpager