usbManager가 NullPointerException을 반환합니다.

Question

UsbManager가 null 포인터 예외를 반환합니다. 여기에 제 코드를 첨부했습니다. 제발 도와주세요.

05-14 16:07:38.312: E/AndroidRuntime(27314): FATAL EXCEPTION: main 
    05-14 16:07:38.312: E/AndroidRuntime(27314): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.ims.act/com.ims.act.ConfirmView}: java.lang.NullPointerException 
    05-14 16:07:38.312: E/AndroidRuntime(27314): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1970) 
    05-14 16:07:38.312: E/AndroidRuntime(27314): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1995) 
    05-14 16:07:38.312: E/AndroidRuntime(27314): at android.app.ActivityThread.access$600(ActivityThread.java:128) 
    05-14 16:07:38.312: E/AndroidRuntime(27314): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1161) 
    05-14 16:07:38.312: E/AndroidRuntime(27314): at android.os.Handler.dispatchMessage(Handler.java:99) 
    05-14 16:07:38.312: E/AndroidRuntime(27314): at android.os.Looper.loop(Looper.java:137) 
    05-14 16:07:38.312: E/AndroidRuntime(27314): at android.app.ActivityThread.main(ActivityThread.java:4517) 
    05-14 16:07:38.312: E/AndroidRuntime(27314): at java.lang.reflect.Method.invokeNative(Native Method) 
    05-14 16:07:38.312: E/AndroidRuntime(27314): at java.lang.reflect.Method.invoke(Method.java:511) 
    05-14 16:07:38.312: E/AndroidRuntime(27314): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:993) 
    05-14 16:07:38.312: E/AndroidRuntime(27314): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:760) 
    05-14 16:07:38.312: E/AndroidRuntime(27314): at dalvik.system.NativeStart.main(Native Method) 
    05-14 16:07:38.312: E/AndroidRuntime(27314): Caused by: java.lang.NullPointerException 
    05-14 16:07:38.312: E/AndroidRuntime(27314): at android.os.Parcel.readException(Parcel.java:1333) 
    05-14 16:07:38.312: E/AndroidRuntime(27314): at android.os.Parcel.readException(Parcel.java:1281) 
    05-14 16:07:38.312: E/AndroidRuntime(27314): at android.hardware.usb.IUsbManager$Stub$Proxy.requestDevicePermission(IUsbManager.java:535) 
    05-14 16:07:38.312: E/AndroidRuntime(27314): at android.hardware.usb.UsbManager.requestPermission(UsbManager.java:361) 
    05-14 16:07:38.312: E/AndroidRuntime(27314): at com.ims.act.ConfirmView.UsbPrinter(ConfirmView.java:92) 
    05-14 16:07:38.312: E/AndroidRuntime(27314): at com.ims.act.ConfirmView.onCreate(ConfirmView.java:77) 
    05-14 16:07:38.312: E/AndroidRuntime(27314): at android.app.Activity.performCreate(Activity.java:4470) 

이제 확인보기가 게시됩니다. 나 .usbManager.requestPermission (장치, mPermissionIntent) 도와주세요 주면 (자), NullPointerException

@Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.confirmpage); 
     System.out.println("test"); 
     inData = getIntent().getStringExtra("ShowText"); 
     Request = getIntent().getStringExtra("Request"); 
     UID = getIntent().getStringExtra("UID"); 
     ReqType = getIntent().getIntExtra("ReqType", 0); 
     SubType = getIntent().getStringExtra("SubType"); 
     Receipt = getIntent().getStringExtra("Receipt"); 
     System.out.println("receipt:" + Receipt); 
     Log.d("CONFIRMPAGE", Request); 
     StaticTranser.textView = (TextView) findViewById(R.id.status); 
     StaticTranser.textView.setText(inData); 
     StaticTranser.textView.setTypeface(Typeface.MONOSPACE); 
     UsbPrinter(); 
    } 

    private void UsbPrinter() { 
     usbManager = (UsbManager) getSystemService(Context.USB_SERVICE); 
     HashMap<String, UsbDevice> deviceList = usbManager.getDeviceList(); 
     Iterator<UsbDevice> it = deviceList.values().iterator(); 
     while (it.hasNext()) { 
      device = it.next(); 
      System.out.println("Devices :" + device.toString()); 
     } 

     PendingIntent mPermissionIntent = PendingIntent.getBroadcast(this,0, 
       new Intent(ACTION_USB_PERMISSION), 0); 

     usbManager.requestPermission(device, mPermissionIntent); 
     registerReceiver(mUsbReceiver, filter); 
    } 

    @Override 
    protected void onResume() { 
     registerReceiver(mUsbReceiver, filter); 
     super.onResume(); 
    } 

    private final BroadcastReceiver mUsbReceiver = new BroadcastReceiver() { 

     @Override 
     public void onReceive(Context context, Intent intent) { 
      String action = intent.getAction(); 

      if (ACTION_USB_PERMISSION.equals(action)) { 
       synchronized (this) { 
        device = (UsbDevice) intent 
          .getParcelableExtra(UsbManager.EXTRA_DEVICE); 

        if (intent.getBooleanExtra(
          UsbManager.EXTRA_PERMISSION_GRANTED, false)) { 
         if (device != null) { 
          getConnection(); 
         } 
        } else { 
         Log.d("BROADCOST RECEIVER", 
           "permission denied for device " + device); 
        } 

        if (UsbManager.ACTION_USB_DEVICE_DETACHED.equals(action)) { 
         if (device != null) { 
          Log.d("CLOSE USB Connection", "Connection closed"); 
          connection.releaseInterface(intf); 
          connection.close(); 
         } 
        } 
       } 
      } 
     } 

    }; 

내가 삼성 모바일 version4.0를 테스트입니다에게 반환합니다. 내 모바일에 usb 프린터를 연결하려고하는데 NullPointerException이 반환됩니다.

Answer 1

androidManifest.xml에 usb 권한을 추가 했습니까?