導航與ListView的抽屜（無法啓動活動ComponentInfo）

Question

我想創建一個導航抽屜，其默認視圖是ListView。

但是，當我設置List的適配器，它只是有一個像下面的一些bug ......

07-07 10:22:34.318: E/AndroidRuntime(26075): FATAL EXCEPTION: main 
07-07 10:22:34.318: E/AndroidRuntime(26075): Process: com.example.android.navigationdrawerexample, PID: 26075 
07-07 10:22:34.318: E/AndroidRuntime(26075): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.android.navigationdrawerexample/com.example.android.navigationdrawerexample.MainActivity}: java.lang.NullPointerException 

有什麼錯我的代碼？

MainActivity.java：http://pastebin.com/pVXKLe7t

Answer 1

Use this code may it work for you as below:- 

     mDrawerList.setAdapter(mNavDrawerListAdapter); 
        mDrawerList.setOnItemClickListener(new OnItemClickListener() { 
         private ArrayList<HashMap<String, String>> siteArray; 

         @Override 
         public void onItemClick(AdapterView<?> arg0, View arg1, int position, long arg3) { 

          if(position<=3){ 
           displayView(position, "",""); 
          }else{ 
           String siteName = mArrayListLat.get(position-4).toString(); 
           siteArray=new DatabaseSites(NavigationActivity.this).getdata(); 
           for(int s=0; s<siteArray.size(); s++){ 
            if(siteArray.get(s).get("name").equals(siteName)){ 
             String siteParam=siteArray.get(s).get("api"); 
             displayView(position, siteName,siteParam); 
            } 
           } 
          } 
         } 
        }); 


private void displayView(int position, String siteName, String sApi) { 
     Fragment fragmentChild = null; 
     String barTitle = null; 
     Bundle mBundle = new Bundle(); 
     switch (position) { 
     case 0: 
      fragmentChild = new ProfileFragment(); 
      mBundle.putString(Constants.USER_ID, ""); 
      fragmentChild.setArguments(mBundle); 
      barTitle = Constants.MY_PROFILE; 
      break; 
     default: 
    fragmentChild = new QuestionFragment(); 
      break; 
     } 

     if (fragmentChild != null) {## Heading ## 
      FragmentManager fragmentManager1 = getSupportFragmentManager(); 
      fragmentManager1.beginTransaction().replace(R.id.frame_container, fragmentChild).addToBackStack(null).commit(); 
      mDrawerList.setItemChecked(position, true); 
      mDrawerList.setSelection(position); 
      try { 
       setTitle(barTitle); 
      } catch (Exception e) { 
       setTitle(Constants.STACKY_LITE); 
       e.printStackTrace(); 
      } 
      mDrawerLayout.closeDrawer(mDrawerList); 
     } else { 
      Log.e("MainActivity", "Error in creating fragment"); 
     } 
    }