AlertDialog.Builder finish() 결과가 NPE

Question

목록 항목을 클릭하면 다운로드 진행률을 나타내는 진행률 표시 줄이 시작되는 앱을 만들려고합니다. 어떤 이유로 인해 목록 항목이 진행률 막대를 표시하지 못하게합니다. 코드는 다음과 같습니다.

final CharSequence[] items = { "View Information", "Lock", "Pin", 
       "Delete", "Ban User", "Ban IP", "Download" }; 

     AlertDialog.Builder builder = new AlertDialog.Builder(this); 
     builder.setTitle("Options"); 
     builder.setItems(items, new DialogInterface.OnClickListener() { 
      public void onClick(DialogInterface dialog, int item) { 
       Toast.makeText(getApplicationContext(), items[item], 
         Toast.LENGTH_SHORT).show(); 
       switch (item) { 
       case 0: 
        Intent i = new Intent(TestActivity.this, ActivityTwo.class); 
        i.putExtra("filename", files.get(position).getFilename()); 
        i.putExtra("orig_filename", files.get(position) 
          .getOriginalFilename()); 
        i.putExtra("date", files.get(position).getDate()); 
        i.putExtra("downloads", files.get(position).getDownloads()); 
        i.putExtra("uploader_ip", files.get(position) 
          .getUploaderIP()); 
        i.putExtra("username", files.get(position).getUsername()); 
        i.putExtra("locked", files.get(position).isLocked()); 
        i.putExtra("pinned", files.get(position).isPinned()); 
        startActivityForResult(i, REQUEST_CODE); 
       case 6: 
        downloadFile(files.get(position).getFilename(), files.get(position).getOriginalFilename()); 
       } 
      } 

     }); 
     AlertDialog alert = builder.create(); 
     alert.show(); 

그리고 진행률 막대를 제어하는 ​​세 가지 방법이 있습니다.

private ProgressDialog progressDialog; 
    public void startProgress() { 
     progressDialog = new ProgressDialog(TestActivity.this); 
     progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL); 
     progressDialog.setMessage("Loading..."); 
     progressDialog.setCancelable(false); 
     Log.d("Download", String.valueOf(progressDialog.getMax())); 
     progressDialog.show(); 
    } 

    public void updateProgress(int currentSize, int totalSize) { 
     Log.d("Download", String.valueOf((currentSize/totalSize) * 100)); 
     progressDialog.setProgress(((currentSize/totalSize) * 100)); 
    } 

    public void closeProgress() { 
     progressDialog.hide(); 
    } 

진행률 표시 줄을 실행하는 다운로드 파일.

11-12 20:17:18.407: E/AndroidRuntime(4728): java.lang.NullPointerException 
11-12 20:17:18.407: E/AndroidRuntime(4728):  at com.evandarwin.android.TestActivity.downloadFile(TestActivity.java:244) 
11-12 20:17:18.407: E/AndroidRuntime(4728):  at com.evandarwin.android.TestActivity$1.onClick(TestActivity.java:143) 
11-12 20:17:18.407: E/AndroidRuntime(4728):  at com.android.internal.app.AlertController$AlertParams$3.onItemClick(AlertController.java:873) 
11-12 20:17:18.407: E/AndroidRuntime(4728):  at android.widget.AdapterView.performItemClick(AdapterView.java:284) 
11-12 20:17:18.407: E/AndroidRuntime(4728):  at android.widget.ListView.performItemClick(ListView.java:3513) 
11-12 20:17:18.407: E/AndroidRuntime(4728):  at android.widget.AbsListView$PerformClick.run(AbsListView.java:1812) 
11-12 20:17:18.407: E/AndroidRuntime(4728):  at android.os.Handler.handleCallback(Handler.java:587) 
11-12 20:17:18.407: E/AndroidRuntime(4728):  at android.os.Handler.dispatchMessage(Handler.java:92) 
11-12 20:17:18.407: E/AndroidRuntime(4728):  at android.os.Looper.loop(Looper.java:130) 
11-12 20:17:18.407: E/AndroidRuntime(4728):  at android.app.ActivityThread.main(ActivityThread.java:3683) 
11-12 20:17:18.407: E/AndroidRuntime(4728):  at java.lang.reflect.Method.invokeNative(Native Method) 
11-12 20:17:18.407: E/AndroidRuntime(4728):  at java.lang.reflect.Method.invoke(Method.java:507) 
11-12 20:17:18.407: E/AndroidRuntime(4728):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:889) 
11-12 20:17:18.407: E/AndroidRuntime(4728):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:647) 
11-12 20:17:18.407: E/AndroidRuntime(4728):  at dalvik.system.NativeStart.main(Native Method) 

Answer 1

당신은 완전한 정보를 넣지 않은 :

if(alertDialog != null) { 
       alertDialog.dismiss(); 
      } 
      startProgress(); 

      // now, read through the input buffer and write the contents to the 
      // file 
      while ((bufferLength = inputStream.read(buffer)) > 0) { 
       // add the data in the buffer to the file in the file output 
       // stream (the file on the sd card 
       fileOutput.write(buffer, 0, bufferLength); 
       // add up the size so we know how much is downloaded 
       downloadedSize += bufferLength; 
       // this is where you would do something to report the prgress, 
       // like this maybe 
       updateProgress(downloadedSize, totalSize); 
      } 

      closeProgress(); 

다음은 예외입니다. 그것의 발생은 downloadFile()입니다. case 0의 끝에서 break를 추가하면