Android viewpager：添加/刪除頁面時出現奇怪的錯誤

我不知道如何解釋這個，所以我上傳了一個視頻Youtube. 當我添加頁面時，一切正常。如果我從列表的末尾開始並逐步移動到第一頁，也刪除頁面作品，但如果我刪除了0-端之間的地方，然後我添加頁面，則會出現空白頁。片段被創建，但觀點不是。Android viewpager：添加/刪除頁面時出現奇怪的錯誤

我的代碼有問題嗎？是的，我已經看到this的問題，返回POSITION_NONE不是一種選擇，因爲我正在從web上下載內容並在listview中顯示它的應用程序，所以每次用戶刪除頁面時重新創建片段不是很有效。

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<Fragment> fragmentslist; 
    private SectionsPagerAdapter mPagerAdapter; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     fragmentslist = new ArrayList<Fragment>(); 
     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：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:tools="http://schemas.android.com/tools" 
android:layout_width="match_parent" 
android:layout_height="match_parent"> 

<android.support.v4.view.ViewPager 
    android:id="@+id/pager" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent"> 
</android.support.v4.view.ViewPager>

fragment_layout.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
android:layout_width="fill_parent" 
android:layout_height="fill_parent" 
android:id="@+id/relativelayout"> 

<TextView 
    android:id="@+id/textView1" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_centerHorizontal="true" 
    android:layout_centerVertical="true" 
    android:text="Large Text" 
    android:textSize="40sp" />

來源

2013-04-25 user1888162