Android如何在我的自定義baseadapter中查找視圖？

Question

我有一個自定義的適配器幾乎完成，除了我想findbyid一個Tablelayout並編程方式將每個孩子變成點擊監聽器。

package com.mhsquire.adapter; 

import android.app.Activity; 
import android.content.Context; 
import android.util.Log; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.BaseAdapter; 
import android.widget.TableLayout; 
import android.widget.TableRow; 
import android.widget.TextView; 
import android.widget.Toast; 

import com.mhsquire.R; 
import com.mhsquire.data.Constants; 
import com.mhsquire.data.Product; 

import java.util.ArrayList; 
import java.util.List; 

import butterknife.ButterKnife; 
import butterknife.InjectViews; 

//import butterknife.Views; 

/** 
* Created by owner on 3/27/2015. 
*/ 
public class FlippableProductAdapter extends BaseAdapter { 

    private Activity activity; 
    private String[] data; 
    private LayoutInflater inflater = null; 
    private ArrayList dataList = new ArrayList(); 
    private View targetView; 
    private int repeatCount = 1; 
    private static String TAG = "Product Adapter"; 
    private int mMaxIndex = 8; 
    private int mIndexSize = 4; 
    private static int mIndex = 0; 

    @InjectViews({R.id.imgtxtProduct, R.id.imgtxtProductDescription}) 
    List<TextView> titleTexts; 

    public FlippableProductAdapter(Activity a, String[] d) { 
     activity = a; 
     data = d; 
     inflater = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE); 

     //imageLoader=new ImageLoader(activity.getApplicationContext()); 
    } 

    public FlippableProductAdapter(Activity a) { 
     activity = a; 
     inflater = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
    } 

    public FlippableProductAdapter(Activity a, ArrayList target) { 
     activity = a; 
     inflater = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
     dataList = target; 

     inflater = LayoutInflater.from(a.getBaseContext()); 
    } 


    private void initializeProductList(ViewHolder holder) { 
     for (int i = 0; i < mMaxIndex; i = i + 2) { 
      if (mIndex + i/2 < Constants.ALLPRODUCTS.size() && !Constants.ALLPRODUCTS.isEmpty()) { 
       holder.textViews.get(i).setText(Constants.ALLPRODUCTS.get(mIndex + i/2).getProductname()); 
       holder.textViews.get(i + 1).setText(Constants.ALLPRODUCTS.get(mIndex + i/2).getProductDescription()); 
      } else { 
       holder.textViews.get(i).setText(""); 
       holder.textViews.get(i + 1).setText(""); 
      } 
     } 
    } 

    View.OnClickListener onClick(final TableRow row, final int col) { 
     return new View.OnClickListener() { 
      public void onClick(View v) { 
       int position = v.getId(); 
       Log.i(TAG, "Clicked Item " + Constants.PRODUCTINDEX); 
       if (Constants.INDEX + position < Constants.ALLPRODUCTS.size()) { 
        titleTexts.get(0).setText(Constants.ALLPRODUCTS.get(Constants.INDEX + position).getProductname()); 
        titleTexts.get(1).setText(Constants.ALLPRODUCTS.get(Constants.INDEX + position).getProductDescription()); 
       } 

      } 
     }; 
    } 

    public static class ViewHolder { 

     public ViewHolder(View view) { 
      ButterKnife.inject(this, view); 
     } 
    } 

    public View getView(int position, View convertView, ViewGroup parent) { 
     View vi = convertView; 
     ViewHolder holder; 
     final int toofar = 2; 


      Constants.FUTUREPOSITION = position; 

     mIndex = Constants.FUTUREPOSITION * mIndexSize; 

     if (convertView == null) { 
      vi = inflater.inflate(R.layout.activity_main_flippable, null); 
      holder = new ViewHolder(vi); 
      vi.setTag(holder); 
     } else holder = (ViewHolder) vi.getTag(); 

     Product target = (Product) dataList.get(position); 

     initializeProductList(holder); 

     TableRow row; 
     TableLayout group = (TableLayout) activity.findViewById(R.id.TableLayout); // NullPointerException Here 
     for (int i = 0; i < group.getChildCount(); i++) 
     { 
      row = (TableRow) group.getChildAt(i); 
      activity.registerForContextMenu(row); 
      row.setId(i); 
      row.setOnClickListener(onClick(row, i)); 
     } 


     return vi; 
    } 

} 

現在我的問題是，我收到上面一行的NullPointerException。什麼是標識TableLayout的正確方法？

Answer 1

創建一個名爲ViewHolder類放在這樣的代碼和OnClck（）：

public static class ViewHolder { 

     public ViewHolder(View view) { 
      ButterKnife.inject(this, view); 

      TableRow row; 
      TableLayout group = (TableLayout) 
      view.findViewById(R.id.TableLayout); // NullPointerException Here 
      for (int i = 0; i < group.getChildCount(); i++) 
      { 
       row = (TableRow) group.getChildAt(i); 
       activity.registerForContextMenu(row); 
       row.setId(i); 
       row.setOnClickListener(onClick(row, i)); 
      } 
     } 

     View.OnClickListener onClick(final TableRow row, final int col) { 
      return new View.OnClickListener() { 
       public void onClick(View v) { 
        int position = v.getId(); 
        Log.i(TAG, "Clicked Item " + Constants.PRODUCTINDEX); 
        if (Constants.INDEX + position < Constants.ALLPRODUCTS.size()) { 
        titleTexts.get(0).setText(Constants.ALLPRODUCTS.get(Constants.INDEX + position).getProductname()); 
        titleTexts.get(1).setText(Constants.ALLPRODUCTS.get(Constants.INDEX + position).getProductDescription()); 
       } 

      } 
     }; 
    } 
    } 

GetView膨脹認爲它傳遞給ViewHolder，然後可以操縱孩子。

public View getView(int position, View convertView, ViewGroup parent) { 
     View vi = convertView; 
     ViewHolder holder; 
     final int toofar = 2; 


      Constants.FUTUREPOSITION = position; 

     mIndex = Constants.FUTUREPOSITION * mIndexSize; 

     if (convertView == null) { 
      vi = inflater.inflate(R.layout.activity_main_flippable, null); 
      holder = new ViewHolder(vi); 
      vi.setTag(holder); 
     } else holder = (ViewHolder) vi.getTag(); 

     Product target = (Product) dataList.get(position); 

     initializeProductList(holder); 




     return vi; 
    } 

} 

Answer 2

嘗試更換您的group由parent觀點：

TableRow row; 

for (int i = 0; i < parent.getChildCount(); i++) 
{ 
    row = (TableRow) parent.getChildAt(i); 
    activity.registerForContextMenu(row); 
    row.setId(i); 
    row.setOnClickListener(onClick(row, i)); 
}