使用EndlessAdapter與SimpleAdapter的NullPointerException

Question

我使用Commonsguy與SimpleAdapter的EndlessAdapter。當我向下滾動而沒有問題時，我可以加載數據，但是當我向上滾動時，我有一個NullPointerException異常。問題是在方法

@Override 
public View getView(int position, View convertView,ViewGroup parent) { 
    return wrapped.getView(position, convertView, parent); 
} 

從類AdapterWrapper。

撥打wrapped.getView(position, convertView,parent)引發了例外，我不知道爲什麼。

這是我實現的EndlessAdapter：

//Inner class in SearchTextActivity 
    class DemoAdapter extends EndlessAdapter { 

     private RotateAnimation rotate = null; 

     DemoAdapter(ArrayList<HashMap<String, String>> result) { 
     super(new SimpleAdapter(SearchTracksActivity.this, 
     result, 
     R.layout.textlist_item, 
     PROJECTION_COLUMNS, 
     VIEW_MAPPINGS)); 

     rotate = new RotateAnimation(0f, 
     360f, 
     Animation.RELATIVE_TO_SELF, 
     0.5f, 
     Animation.RELATIVE_TO_SELF, 
     0.5f); 
     rotate.setDuration(600); 
     rotate.setRepeatMode(Animation.RESTART); 
     rotate.setRepeatCount(Animation.INFINITE); 
     } 

     @Override 
     protected View getPendingView(ViewGroup parent) { 
     View row=getLayoutInflater().inflate(R.layout.textlist_item, null); 

     View child=row.findViewById(R.id.title); 
     child.setVisibility(View.GONE); 

     child=row.findViewById(R.id.username); 
     child.setVisibility(View.GONE); 

     child=row.findViewById(R.id.throbber); 
     child.setVisibility(View.VISIBLE); 
     child.startAnimation(rotate); 

     return row; 
     } 


     @Override 
     @SuppressWarnings("unchecked") 
     protected void rebindPendingView(int position, View row) { 
     HashMap<String, String> res = (HashMap<String, String>)getWrappedAdapter().getItem(position); 


     View child=row.findViewById(R.id.title); 
     ((TextView)child).setText(res.get("title")); 
     child.setVisibility(View.VISIBLE);  

     child=row.findViewById(R.id.username); 
     ((TextView)child).setText(res.get("username")); 
     child.setVisibility(View.VISIBLE); 

     ImageView throbber=(ImageView)row.findViewById(R.id.throbber); 
     throbber.setVisibility(View.GONE); 
     throbber.clearAnimation(); 

     } 

     boolean mFinal = true; 

     @Override 
     protected boolean cacheInBackground() { 

     EditText searchText = (EditText)findViewById(R.id.searchText); 
     String textToSearch = searchText.getText().toString(); 

     Util.getSc().searchText(textToSearch , offset, limit, new ResultListener<ArrayList<Text>>() { 

     @Override 
     public void onError(Exception e) { 
     e.toString(); 
     mFinal = false; 
     } 

     @Override 
     public void onSuccess(ArrayList<Text> result) { 


     if(result.size() == 0){ 
      mFinal = false; 
     }else{ 
      texts.addAll(result); 

      offset++; 
     } 
     } 
     }); 

     return mFinal; 
     } 

     @Override 
     protected void appendCachedData() { 

     for(Text text : texts){ 
     result.add(text.getMapValues()); 
     } 
     texts.clear(); 
     } 
    } 

我使用這種方式：

public class SearchTextActivity extends AbstractListActivity { 

private static final String[] PROJECTION_COLUMNS = new String[] { 
    TextStore.Text.TITLE, 
    TextStore.Text.USER_NAME}; 

private static final int[] VIEW_MAPPINGS = new int[] { 
    R.id.Text_title, 
    R.id.Text_username}; 

ArrayList<HashMap<String, String>> result; 

static ArrayList<Text> texts; 
static int offset = 0; 
static int limit = 1; 

@Override 
void onAbstractCreate(Bundle savedInstance) { 
    setContentView(R.layout.search_tracks); 
    setupViews(); 
} 

private void setupViews() { 

    ImageButton searchButton = (ImageButton)findViewById(R.id.searchButton); 
    updateView(); 
} 

SimpleAdapter adapter; 

void updateView(){ 
    if(result == null) { 
    result = new ArrayList<HashMap<String, String>>(); 
    } 

    if(tracks == null) { 
    texts = new ArrayList<Text>(); 
    } 
} 

public void sendQuery(View v){ 
    offset = 0; 
    texts.clear(); 
    result.clear(); 

    setListAdapter(new DemoAdapter(result)); 
} 
} 

有誰知道可能是什麼問題呢？

Answer 1

它位於SimpleAdapter中。

我想先擺脫EndlessAdapter的開始，只是有你的清單上的SimpleAdapter。

如果這樣的話，那麼EndlessAdapter可能會有一個錯誤，使用它所包含的適配器 - 在這種情況下，我需要一個演示錯誤的示例項目。

如果SimpleAdapter在沒有EndlessAdapter的情況下失敗，則需要更多地調查您如何設置SimpleAdapter。