ViewPager，FragmentStatePagerAdapter，ListFragment每个片段的单独列表数据

Question

我有一个ViewPager，其中包含动态页数。每个页面都需要从数据库中读取并显示该页面的数据集。

我比较当前选择的页面标题与数据库“用户名”中的第一个值，以检查数据是否与该页面相关。

我的片段虽然没有正确显示数据。我试图在onCreateView中设置一个arrayAdapter，但它并没有调用创建每个片段。在我的测试案例中，我有三个片段，user1，user2，user3。 onCreateView最初是在user1上调用的，然后当我滑回到user2时再次调用onCreateView，而不再为user1或user3再次调用。

我需要能够为每个片段专门设置arrayAdapter，因为每个片段都会显示不同的值数组。

PagerAdapter

public class ExamplePagerAdapter extends FragmentStatePagerAdapter implements TitleProvider{ 

     private Map<Integer, UserFragment> mPageReferenceMap = new HashMap<Integer, UserFragment>(); 

     public ExamplePagerAdapter(FragmentManager fm) { 
      super(fm); 
     } 

     @Override 
     public int getCount() { 
      return user; 
     } 

     @Override 
     public Fragment getItem(int position) { 
      Fragment fragment = new UserFragment(); 

      Bundle args = new Bundle(); 
      fragment.setArguments(args);   
      return fragment; 
     } 

     @Override 
     public String getTitle(int pos) { 
      return "@"+users[pos].getName(); 
     } 

     @Override 
     public void destroyItem(View container, int position, Object object) {    
      mPageReferenceMap.remove(Integer.valueOf(position)); 
     } 
    } 

UserFragment

public class UserFragment extends ListFragment { 
     Context ctx; 
     View v; 
     Button mAddEntry; 
     static int p; 
     static ArrayList<String> entryArray; 

     @Override 
     public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
      ctx = container.getContext(); 
      if (v != null) 
       return v; 

      v = inflater.inflate(R.layout.user_fragment, container, false); 
      mAddEntry = (Button) v.findViewById(R.id.entry_b); 
      mAddEntry.setOnClickListener(new OnClickListener() { 
       @Override 
       public void onClick(View v) { 
        Bundle b = new Bundle(); 
        b.putInt("pos", p); 
        Intent mi = new Intent(v.getContext(), EntryAdd.class); 
        mi.putExtras(b); 
        startActivity(mi); 
       } 
      });    
      updateUserFrag(); 
      return v;  
     }  

     public void updateUserFrag() {   
      entryArray = new ArrayList<String>(); 
      StringBuilder sb = new StringBuilder(); 
      final DBAdapter db = new DBAdapter(ctx); 
      db.open(); 
      Cursor c = db.getAllEntries(); 
      try { 
       while (c.moveToNext()) { 
        if (c.getString(0).equals(MainActivity.users[p].getName())) { 
         sb.append(c.getString(1)); 
         entryArray.add(sb.toString()); 
        } 
       } 
      } catch (Exception e) {} 
      c.close(); 
      db.close(); 

      ArrayAdapter<String> a = new ArrayAdapter<String>(ctx, android.R.layout.simple_list_item_1, entryArray); 
      setListAdapter(a); 
     } 

} 

基本上，我只需要我可以使用给每个片段其创建时其数据的方法。 onCreateView（）不会为每个片段调用，所以这对我没有用。

UPDATE 我想我已经差不多了，但是我无法弄清楚这最后一部分。我使用TitlePageIndicators onPageSelected方法发送数据到我的片段处理程序。

TitlePageIndicator indicator = (TitlePageIndicator)findViewById(R.id.indicator); 
    indicator.setViewPager(pager, 0); 
    indicator.setOnPageChangeListener(new OnPageChangeListener() { 
     @Override 
     public void onPageSelected(int position) { 
       Message msg = UserFragment.handy.obtainMessage(); 
       Bundle b = new Bundle(); 
       b.putInt("m", 0); 
       b.putInt("p", position); 
       b.putStringArrayList("e", updateUserFrag(position)); 
       msg.setData(b); 
       UserFragment.handy.handleMessage(msg);     
     } 

处理器

static Handler handy = new Handler() { 
     public void handleMessage(Message msg) { 
      int p = msg.getData().getInt("p"); 
      int m = msg.getData().getInt("m"); 
      ArrayList<String> e = msg.getData().getStringArrayList("e"); 

      switch (m) { 
       case 0: 
        Log.d("HANDLER", Integer.toString(p)); 
        for (int i=0;i<e.size();i++) { 
         //Log.d("ENTRY", e.get(i)); 
        } 
       break; 
      } 
     } 
    }; 

的问题是，该处理程序被调用的时候，一个ArrayAdapter已经设置了，我能找到一种方法来触发数据的刷新。

Answer 1

@Override 
    public void onPageSelected(int position) { 
      Message msg = UserFragment.handy.obtainMessage(); 
      Bundle b = new Bundle(); 
      b.putInt("m", 0); 
      b.putInt("p", position); 
      b.putStringArrayList("e", updateUserFrag(position)); 
      msg.setData(b); 
      UserFragment.handy.handleMessage(msg);     
    } 

    public ArrayList<String> updateUserFrag (int p) {   
     entryArray = new ArrayList<String>(); 
     StringBuilder sb = new StringBuilder(); 
     DBAdapter db = new DBAdapter(this); 
     db.open(); 
     Cursor c = db.getAllEntries(); 
     try { 
      while (c.moveToNext()) { 
       if (c.getString(0).equals(users[p].getName())) { 
        sb.append(c.getString(1)); 
        entryArray.add(sb.toString()); 
       } 
      } 
     } catch (Exception e) {} 
     c.close(); 
     db.close(); 
     return entryArray;   
    } 

UserFragment

public class UserFragment extends ListFragment { 
     Context ctx; 
     View v; 
     Button mAddEntry; 
     static int p; 
     static ArrayList<String> entryArray; 
     static ArrayAdapter<String> a; 

     @Override 
     public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
      ctx = container.getContext(); 
      if (v != null) 
       return v; 

      v = inflater.inflate(R.layout.user_fragment, container, false); 
      mAddEntry = (Button) v.findViewById(R.id.entry_b); 
      mAddEntry.setOnClickListener(new OnClickListener() { 
       @Override 
       public void onClick(View v) { 
        Bundle b = new Bundle(); 
        b.putInt("pos", p); 
        Intent mi = new Intent(v.getContext(), EntryAdd.class); 
        mi.putExtras(b); 
        startActivity(mi); 
       } 
      });  
      updateUserFrag(p); 
      return v;  
     }  

     public void updateUserFrag (int p) {   
      entryArray = new ArrayList<String>(); 
      a = new ArrayAdapter<String>(ctx, android.R.layout.simple_list_item_1, entryArray); 
      setListAdapter(a); 
     } 

     static Handler handy = new Handler() { 
      public void handleMessage(Message msg) { 
       int p = msg.getData().getInt("p"); 
       int m = msg.getData().getInt("m"); 
       ArrayList<String> e = msg.getData().getStringArrayList("e"); 

       switch (m) { 
        case 0: 
         Log.d("HANDLER", Integer.toString(p)); 
         entryArray.clear(); 
         for (int i=0;i<e.size();i++) { 
          entryArray.add(e.get(i)); 
         } 
         a.notifyDataSetChanged(); 
        break; 
       } 
      } 
     };  
}