Android viewpager:添加/删除页面时的奇怪错误

我不知道如何解释这个,所以我在Youtube上传了一个video。 当我添加页面时,一切正常。 如果我从列表的末尾开始并逐步移动到第一页,也删除页面工作,但如果我删除0之间和之后的某处我添加页面,我得到一个空白页面。 片段已创建但视图不是。

我的代码有问题吗? 是的,我已经看到了这个问题,返回POSITION_NONE不是一个选项,因为应用程序我正在从web下载内容并将其显示在listview中,因此每次用户删除页面时重新创建片段都不是很有效。

 Button click: Result: Add page [Fragment 1] Add page [Fragment 1][Fragment 2] Add page [Fragment 1][Fragment 2][Fragment 3] remove page(position2) [Fragment 1][Fragment 2] remove page(position1) [Fragment 1] Add page [Fragment 1][Fragment 2] remove page(position1) [Fragment 1] remove page(position0) ---No pages--- Add page [Fragment 0] Add page [Fragment 0][Fragment 1] Add page [Fragment 0][Fragment 1][Fragment 2] add page [Fragment 0][Fragment 1][Fragment 2][fragment 3] remove page(position2) [Fragment 0][Fragment 1][Fragment 3] add page [Fragment 0][Fragment 1][Fragment 3][Blank page] remove page(position0) [Fragment 1][Fragment 3][Fragment 3][Blank page] 

MainActivity.class

  public class MainActivity extends FragmentActivity { private static final String TAG = "MainActivity"; private ViewPager mViewpager; private ArrayList fragmentslist; private SectionsPagerAdapter mPagerAdapter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); fragmentslist = new ArrayList(); mPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager()); mViewpager = (ViewPager)findViewById(R.id.pager); mViewpager.setAdapter(mPagerAdapter); mViewpager.setOffscreenPageLimit(4); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.main, menu); return true; } @Override public boolean onOptionsItemSelected (MenuItem item){ switch(item.getItemId()){ case R.id.menu_add_page: Bundle bundle = new Bundle(); bundle.putInt("Position", fragmentslist.size()); fragment frag = new fragment(); frag.setArguments(bundle); fragmentslist.add(frag); mPagerAdapter.notifyDataSetChanged(); mViewpager.setCurrentItem(fragmentslist.indexOf(frag)); Log.i(TAG, "Add fragment"); break; case R.id.menu_remove_page: if(fragmentslist.size() > 0){ mPagerAdapter.removeItem(mViewpager.getCurrentItem()); } Log.i(TAG, "Removing page " + mViewpager.getCurrentItem()); break; } return true; } public class SectionsPagerAdapter extends FragmentPagerAdapter { public SectionsPagerAdapter(FragmentManager fm) { super(fm); } @Override public Fragment getItem(int position) { return fragmentslist.get(position); } @Override public int getCount() { return fragmentslist.size(); } @Override public int getItemPosition(Object object){ int index = fragmentslist.indexOf(object); if(index != -1){ Log.i(TAG, "Position: " + index); return index; } else{ Log.i(TAG, "POSITION_NONE"); return POSITION_NONE; } } public void removeItem(int position){ Fragment fragment = (Fragment)fragmentslist.get(position); getSupportFragmentManager().beginTransaction().remove(fragment).commit(); fragmentslist.remove(position); notifyDataSetChanged(); } } public static class fragment extends Fragment{ private String colors[] = {"#FF0000", "#00FF00", "#FFFF00", "#FF6600"}; public View onCreateView(LayoutInflater inflater, ViewGroup root, Bundle savedInstanceState){ View mView = inflater.inflate(R.layout.fragment_layout, null); RelativeLayout layout = (RelativeLayout)mView.findViewById(R.id.relativelayout); TextView text = (TextView)mView.findViewById(R.id.textView1); int position = this.getArguments().getInt("Position"); text.setText("Page: " + position); layout.setBackgroundColor(Color.parseColor(colors[position])); Log.i("fragment", "Page: " + position + " view created"); return mView; } } } 

activity_main.xml中:

    

fragment_layout.xml

   

在添加或删除列表中的项目之前,请尝试执行mViewpager.setAdapter(null)。 然后,将适配器设置回mPagerAdapter。 似乎ViewPager不是为处理插入或删除而设计的,除了从列表末尾开始。

我有可能对您有用的示例代码。 看看ViewPager示例 。