类看到array.lengh，但没有它的数据

Question

我在我的代码中有一个奇怪的错误，我看不到问题。我有一个主要课程，我在里面有一门课。我在主类中声明了一个数组列表，如果我在该类的某个部分访问它，我可以获得所有信息，但是当我在内部类访问它时，它无法看到数据。为什么？

内部类是制作视图列表的BaseAdapter。我把它叫做从OnCreate中捆绑为：

public class Main extends ListActivity implements OnClickListener { 
//new adapter 
private EfficientAdapter adap; 
//The variable which makes the error 
public static ArrayList<String> data2 = new ArrayList<String>();  
protected static Context mContext=null; 

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

    data2.clear(); 
    data2.add("just adding 1"); 
    adap = new EfficientAdapter(this); 
    setListAdapter(adap); 

和内部类（问题出在它的结束）：

public static class EfficientAdapter extends BaseAdapter implements Filterable { 
    private LayoutInflater mInflater; 
    private Context context; 

    public EfficientAdapter(Context context) { 
     // Cache the LayoutInflate to avoid asking for a new one each time. 
     mInflater = LayoutInflater.from(context); 
     this.context = context; 
    } 

    /** 
    * Make a view to hold each row. 
    * 
    * @see android.widget.ListAdapter#getView(int, android.view.View, 
    *  android.view.ViewGroup) 
    */ 
    public View getView(final int position, View convertView, ViewGroup parent) { 
     // A ViewHolder keeps references to children views to avoid 
     // unneccessary calls 
     // to findViewById() on each row. 
     ViewHolder holder; 

     // When convertView is not null, we can reuse it directly, there is 
     // no need 
     // to reinflate it. We only inflate a new View when the convertView 
     // supplied 
     // by ListView is null. 
     if (convertView == null) { 
      convertView = mInflater.inflate(R.layout.pruebas, null); 

      // Creates a ViewHolder and store references to the two children 
      // views 
      // we want to bind data to. 
      holder = new ViewHolder(); 
      holder.textLine = (TextView) convertView.findViewById(R.id.pr2); 
      holder.buttonLine = (ImageButton) convertView.findViewById(R.id.pr1); 


      convertView.setOnClickListener(new OnClickListener() { 
       private int pos = position; 

       @Override 
       public void onClick(View v) { 
        Toast.makeText(context, "Click-" + String.valueOf(pos), Toast.LENGTH_SHORT).show(); 
       } 
      }); 

      holder.buttonLine.setOnClickListener(new OnClickListener() { 
       private int pos = position; 

       @Override 
       public void onClick(View v) { 
        Toast.makeText(context, "Delete-" + String.valueOf(pos), Toast.LENGTH_SHORT).show();  
       } 
      }); 
      convertView.setTag(holder); 
     } else { 
      // Get the ViewHolder back to get fast access to the TextView 
      // and the ImageView. 
      holder = (ViewHolder) convertView.getTag(); 
     } 

     // Bind the data efficiently with the holder. 
     holder.textLine.setText(String.valueOf(position)); 

     return convertView; 
    } 

    static class ViewHolder { 
     TextView textLine; 
     ImageButton buttonLine; 
    } 

    @Override 
    public Filter getFilter() { 
     // TODO Auto-generated method stub 
     return null; 
    } 

    @Override 
    public long getItemId(int position) { 
     // TODO Auto-generated method stub 
     return 0; 
    } 


//Here it comes the problem. Before editing my program this code was provide to include  only a few values from 
a String array declared at the same moment of data2 called data. What I do now is to  declare an arraylist so 
I can include more values and then I refresh the adaptor and here I pass the arraylist  to an array to be equal as 
it was before. 
    @Override 
    public int getCount() { 
     // TODO Auto-generated method stub 
     String [] change = (String[]) data2.toArray(new String[data2.size()]); 
     return change.length; 
     //return data.length; 
    } 
//Same problem 
    @Override 
    public Object getItem(int position) { 
     // TODO Auto-generated method stub 

     String [] change = (String[]) data2.toArray(new String[data2.size()]); 
     return change[position]; 
     //return data[position]; 
    } 

} 

奇怪的是，这baseAdapter是一个ListView和当它更新它的数据时，会有像arraylist.length那样的行，但是它的数据不包含它，并且所有行在点击时都被检测为相同。

Answer 1

问题解决了。 我将代码更改为这一个：techdroid.kbeanie.com/2009/07/custom-listview-for-android.html

Answer 2

试试这个：

@Override 
public int getCount() { 
    if(Main.data2!=null) 
    { 
     return Main.data2.size(); 
    } 
    else 
    { 
     return 0; 
    } 
} 

@Override 
public String getItem(int position) { 
    if(Main.data2!=null) 
    { 
     return Main.data2.get(position); 
    } 
    else 
    { 
     return null; 
    } 
}