ボタンクリックリスナーを使用してレイアウトを拡張するにはどうすればよいですか？

Question

.net Webサービスからデータを取り出して、リストビューに表示しようとしています。私がしたコーディングは以下の通りです

public class DisplayList extends AppCompatActivity { 

private static final String TAG_CATEGORY = "main_name"; 
private static final String TAG_SUBCAT = "cat_name"; 
private static final String TAG_CODE = "code"; 
private static final String TAG_NAME = "name"; 
private static final String TAG_RATE = "rate"; 
private static final String TAG_RATE2 = "rate2"; 
private static final String TAG_RATE3 = "rate3"; 
private static final String TAG_IMAGE = "img"; 

ImageAdapter mImageAdapter = null; 
ListView mListView = null; 

ArrayList<DetailsVO> mListDetails = null; 

String subc; 


@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_display_list); 

    mListView = (ListView) findViewById(R.id.list_view); 

    Bundle extras = getIntent().getExtras(); 
    if (extras != null) { 
     subc = extras.getString("Subcat"); 
    } 

    new AsyncCallSoap1().execute(); 

} 

public class AsyncCallSoap1 extends AsyncTask<String,Void,String> { 
    private final ProgressDialog dialog=new ProgressDialog(DisplayList.this); 

    @Override 
    protected String doInBackground(String... params) { 
     CallSoap com=new CallSoap(); 
     String SOAP_ACTION="http://tempuri.org/IprotechService/SelectSuCatgeory"; 
     String OPERATION_NAME="SelectSuCatgeory"; 
     String response = com.getDetails(OPERATION_NAME,SOAP_ACTION); 

     if(response!=null){ 
      try { 

       JSONArray array1 = new JSONArray(response); 

       for(int i=0;i<array1.length();i++) 
       { 

        final DetailsVO detailsVO = new DetailsVO(); 
        JSONObject obj1 = array1.getJSONObject(i); 

        String out_category = obj1.getString(TAG_CATEGORY); 
        String out_subcat = obj1.getString(TAG_SUBCAT); 
        String out_code = obj1.getString(TAG_CODE); 
        String out_name = obj1.getString(TAG_NAME); 
        String out_rate = obj1.getString(TAG_RATE); 
        String out_rate2 = obj1.getString(TAG_RATE2); 
        String out_rate3 = obj1.getString(TAG_RATE3); 
        String out_img = obj1.getString(TAG_IMAGE); 

        // Toast.makeText(DetailsList.this, categoryId, Toast.LENGTH_LONG).show(); 

        detailsVO.setName(out_name); 
        detailsVO.setRate(out_rate); 

        mListDetails.add(detailsVO); 
       } 

      } catch (JSONException e) { 
       e.printStackTrace(); 
      } 
     } 
     return response; 
    } 

    @Override 
    protected void onPreExecute() { 
     super.onPreExecute(); 
     //Showing progress dialog 
     dialog.setMessage("Please wait..."); 
     dialog.setCancelable(false); 
     dialog.show(); 
    } 

    @Override 
    protected void onPostExecute(String result) { 
     super.onPostExecute(result); 
     dialog.dismiss(); 

     if(mListDetails != null){ 
      mImageAdapter = new ImageAdapter(DisplayList.this, mListDetails); 
      mListView.setAdapter(mImageAdapter); 
     } 

    } 
} 

public class ImageAdapter extends BaseAdapter { 
    private Context mContext; 
    private ArrayList<DetailsVO> mItems; 
    private ArrayList<DetailsVO> mOriginalItems; 

    public ImageAdapter(Context context, ArrayList<DetailsVO> items) { 
     this.mContext = context; 
     this.mItems = items; 
    } 

    @Override 
    public int getCount() { 
     return mItems.size(); 
    } 

    @Override 
    public DetailsVO getItem(int position) { 
     return mItems.get(position); 
    } 

    @Override 
    public long getItemId(int position) { 
     return position; 
    } 

    public ArrayList<DetailsVO> getItems(){ 
     return mItems; 
    } 

    public View getView(int position, View convertView, ViewGroup parent) { 
     if (convertView == null) { 
      LayoutInflater mInflater = (LayoutInflater) mContext.getSystemService(Activity.LAYOUT_INFLATER_SERVICE); 
      convertView = mInflater.inflate(R.layout.row_layout, null); 

     } 

     DetailsVO detailsVO = mItems.get(position); 

     View listView = (View) convertView; 

     // set value into textview 
     TextView textTitle = (TextView) listView.findViewById(R.id.textView2); 

     TextView textRate = (TextView) listView.findViewById(R.id.textView3); 

     Button btnMap = (Button) listView.findViewById(R.id.btn_add); 
     btnMap.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 

       Toast.makeText(v.getContext(), "Feature coming soon...", Toast.LENGTH_SHORT).show(); 

      } 
     }); 

     textTitle.setText(detailsVO.getName()); 
     textRate.setText(detailsVO.getRate()); 

     btnMap.setTag(detailsVO); 

     return listView; 
    } 

} 

しかし、私はレイアウトを膨らませることができません。 below.PleaseがmListDetailsを初期化しないので問題

07-19 11:40:44.503 28989-29218/com.example.mayur.easygrocery E/AndroidRuntime: FATAL EXCEPTION: AsyncTask #1 
                      java.lang.RuntimeException: An error occured while executing doInBackground() 
                       at android.os.AsyncTask$3.done(AsyncTask.java:299) 
                       at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352) 
                       at java.util.concurrent.FutureTask.setException(FutureTask.java:219) 
                       at java.util.concurrent.FutureTask.run(FutureTask.java:239) 
                       at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230) 
                       at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080) 
                       at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573) 
                       at java.lang.Thread.run(Thread.java:856) 
                      Caused by: java.lang.NullPointerException 
                       at com.example.mayur.easygrocery.DisplayList$AsyncCallSoap1.doInBackground(DisplayList.java:108) 
                       at com.example.mayur.easygrocery.DisplayList$AsyncCallSoap1.doInBackground(DisplayList.java:73) 
                       at android.os.AsyncTask$2.call(AsyncTask.java:287) 
                       at java.util.concurrent.FutureTask.run(FutureTask.java:234) 
                       at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)  
                       at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)  
                       at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)  
                       at java.lang.Thread.run(Thread.java:856)  
07-19 11:40:45.104 28989-28989/com.example.mayur.easygrocery E/WindowManager: Activity com.example.mayur.easygrocery.DisplayList has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{42355370 V.E..... R......D 0,0-456,144} that was originally added here 
                      android.view.WindowLeaked: Activity com.example.mayur.easygrocery.DisplayList has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{42355370 V.E..... R......D 0,0-456,144} that was originally added here 
                       at android.view.ViewRootImpl.<init>(ViewRootImpl.java:464) 
                       at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:235) 
                       at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:73) 
                       at android.app.Dialog.show(Dialog.java:282) 
                       at com.example.mayur.easygrocery.DisplayList$AsyncCallSoap1.onPreExecute(DisplayList.java:124) 
                       at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:586) 
                       at android.os.AsyncTask.execute(AsyncTask.java:534) 
                       at com.example.mayur.easygrocery.DisplayList.onCreate(DisplayList.java:69) 
                       at android.app.Activity.performCreate(Activity.java:5326) 
                       at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1097) 
                       at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2218) 
                       at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2309) 
                       at android.app.ActivityThread.access$700(ActivityThread.java:157) 
                       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1289) 
                       at android.os.Handler.dispatchMessage(Handler.java:99) 
                       at android.os.Looper.loop(Looper.java:176) 
                       at android.app.ActivityThread.main(ActivityThread.java:5317) 
                       at java.lang.reflect.Method.invokeNative(Native Method) 
                       at java.lang.reflect.Method.invoke(Method.java:511) 
                       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102) 
                       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869) 
                       at dalvik.system.NativeStart.main(Native Method) 

Answer 1

を整理するために私を助けるように私が取得していますエラーが言及されています。 onPreExecuteまたはOnCreate()

  @Override 
      protected void onPreExecute() { 
       super.onPreExecute(); 
       //Showing progress dialog 
       mListDetails = new Arraylist<DetailsVO>(); 
       dialog.setMessage("Please wait..."); 
       dialog.setCancelable(false); 
       dialog.show(); 
      }