ViewPager PagerAdapter 不更新视图 [英] ViewPager PagerAdapter not updating the View

问题描述

我正在使用兼容性库中的 ViewPager.我已经成功地让它显示了几个我可以翻阅的视图.

I'm using the ViewPager from the compatibility library. I have succussfully got it displaying several views which I can page through.

但是，我很难弄清楚如何使用一组新的视图更新 ViewPager.

However, I'm having a hard time figuring out how to update the ViewPager with a new set of Views.

我尝试了各种方法，例如调用 mAdapter.notifyDataSetChanged()、mViewPager.invalidate() 甚至每次我想使用时都创建一个全新的适配器一个新的数据列表.

I've tried all sorts of things like calling mAdapter.notifyDataSetChanged(), mViewPager.invalidate() even creating a brand new adapter each time I want to use a new List of data.

没有任何帮助，文本视图与原始数据保持不变.

Nothing has helped, the textviews remain unchanged from the original data.

更新:我做了一个小测试项目，几乎可以更新视图.我将粘贴下面的课程.

Update: I made a little test project and I've almost been able to update the views. I'll paste the class below.

似乎没有更新的是第二个视图，B"仍然存在，按下更新按钮后它应该显示Y".

What doesn't appear to update however is the 2nd view, the 'B' remains, it should display 'Y' after pressing the update button.

public class ViewPagerBugActivity extends Activity {

    private ViewPager myViewPager;
    private List<String> data;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        data = new ArrayList<String>();
        data.add("A");
        data.add("B");
        data.add("C");

        myViewPager = (ViewPager) findViewById(R.id.my_view_pager);
        myViewPager.setAdapter(new MyViewPagerAdapter(this, data));

        Button updateButton = (Button) findViewById(R.id.update_button);
        updateButton.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                updateViewPager();
            }
        });
    }

    private void updateViewPager() {
        data.clear();
        data.add("X");
        data.add("Y");
        data.add("Z");
        myViewPager.getAdapter().notifyDataSetChanged();
    }

    private class MyViewPagerAdapter extends PagerAdapter {

        private List<String> data;
        private Context ctx;

        public MyViewPagerAdapter(Context ctx, List<String> data) {
            this.ctx = ctx;
            this.data = data;
        }

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

        @Override
        public Object instantiateItem(View collection, int position) {
            TextView view = new TextView(ctx);
            view.setText(data.get(position));
            ((ViewPager)collection).addView(view);
            return view;
        }

        @Override
        public void destroyItem(View collection, int position, Object view) {
             ((ViewPager) collection).removeView((View) view);
        }

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

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

        @Override
        public void restoreState(Parcelable arg0, ClassLoader arg1) {
        }

        @Override
        public void startUpdate(View arg0) {
        }

        @Override
        public void finishUpdate(View arg0) {
        }
    }
}

推荐答案

将 FragmentPagerAdapter 更改为 FragmentStatePagerAdapter.

覆盖 getItemPosition() 方法并返回 POSITION_NONE.

Override getItemPosition() method and return POSITION_NONE.

最终，它会在视图寻呼机上监听 notifyDataSetChanged().

Eventually, it will listen to the notifyDataSetChanged() on view pager.

这篇关于ViewPager PagerAdapter 不更新视图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！