java - java.lang.IllegalArgumentException 导致指定为非 null 的参数为 null

Question

拍照并单击相机界面上的复选标记按钮后，出现以下导致应用崩溃的异常:

Caused by: java.lang.IllegalArgumentException: Parameter specified as non-null is null: method kotlin.jvm.internal.Intrinsics.checkParameterIsNotNull, parameter data

仅当我尝试拍照时才会出现此异常，而当我从图库中选择图像时不会出现此异常。

异常表明 data 参数作为 null 传递，而它应该是 non-null 并指向 kotlin 文件功能。研究这个问题后，我发现我需要将 ? 传递给上述参数。 (来源:this和this)，但现在我得到了

Only safe (?.) or non-null asserted (!!.) calls are allowed on a nullable receiver of type Intent?

我没有使用 Kotlin 的经验，所以不确定这对我来说是否是正确的解决方案。如果有人遇到过这样的异常，我想知道如何解决这个问题。

代码如下:

void _checkCameraPermission() {
    PermissionHandler()
        .checkPermissionStatus(PermissionGroup.camera)
        .then((status) {
      if (status == PermissionStatus.granted) {
        getImage(ImageSource.camera);
      } else {
        _askCameraPermission();
      }
    });
  }

  void _askCameraPermission() {
    PermissionHandler()
        .requestPermissions([PermissionGroup.camera]).then(_onStatusRequested);
  }

  void _onStatusRequested(Map<PermissionGroup, PermissionStatus> value) {
    final status = value[PermissionGroup.camera];
    if (status == PermissionStatus.granted) {
      getImage(ImageSource.camera);
    }
  }
  Future uploadFile(imageFile) async {
//    String fileName = DateTime.now().millisecondsSinceEpoch.toString();
    String fileName = "images/" + new Uuid().v4() + ".jpg";
    StorageReference reference = FirebaseStorage.instance.ref().child(fileName);
    StorageUploadTask uploadTask = reference.putFile(imageFile);

    await uploadTask.onComplete.then((value) {
      reference.getDownloadURL().then((result) {
        // result is the file URL
        if (result != null) {
          setState(() {
            isLoading = false;
          });
          onSendMessage(result, 2);
        }
      });
    });
  }

异常日志:

E/AndroidRuntime( 8402): FATAL EXCEPTION: main
E/AndroidRuntime( 8402): Process: com.quickcarl.qcflutterpro, PID: 8402
E/AndroidRuntime( 8402): java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=2343, result=-1, data=null} to activity {com.quickcarl.qcflutterpro/com.quickcarl.qcflutterpro.MainActivity}: **java.lang.IllegalArgumentException: Parameter specified as non-null is null: method kotlin.jvm.internal.Intrinsics.checkParameterIsNotNull, parameter data**
E/AndroidRuntime( 8402):    at android.app.ActivityThread.deliverResults(ActivityThread.java:3699)
E/AndroidRuntime( 8402):    at android.app.ActivityThread.handleSendResult(ActivityThread.java:3742)
E/AndroidRuntime( 8402):    at android.app.ActivityThread.-wrap16(ActivityThread.java)
E/AndroidRuntime( 8402):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1393)
E/AndroidRuntime( 8402):    at android.os.Handler.dispatchMessage(Handler.java:102)
E/AndroidRuntime( 8402):    at android.os.Looper.loop(Looper.java:148)
E/AndroidRuntime( 8402):    at android.app.ActivityThread.main(ActivityThread.java:5417)
E/AndroidRuntime( 8402):    at java.lang.reflect.Method.invoke(Native Method)
E/AndroidRuntime( 8402):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
E/AndroidRuntime( 8402):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
E/AndroidRuntime( 8402): Caused by: java.lang.IllegalArgumentException: Parameter specified as non-null is null: method kotlin.jvm.internal.Intrinsics.checkParameterIsNotNull, parameter data
E/AndroidRuntime( 8402):    at com.quickcarl.qcflutterpro.MainActivity.onActivityResult(MainActivity.kt)
E/AndroidRuntime( 8402):    at android.app.Activity.dispatchActivityResult(Activity.java:6428)
E/AndroidRuntime( 8402):    at android.app.ActivityThread.deliverResults(ActivityThread.java:3695)
E/AndroidRuntime( 8402):    ... 9 more

主要 Activity 代码:

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent) {
        super.onActivityResult(requestCode, resultCode, data)

        if(requestCode == VIDEO_SCREEN_REQUEST_CODE) {
            if(resultCode == Activity.RESULT_OK) {
                sendStringMessageToFlutter(data.getStringExtra("roomName"), "completeRoom")
            }
        }
    }

Answer 1

更改 onActivityResult 方法的签名，如下所示:

覆盖 fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {}

这将解决问题。 data 可以为 null，但您将其声明为 non-null

<小时/>

编辑:

然后，在函数主体中，确保在检索字符串时检查是否为空:

if(resultCode == Activity.RESULT_OK) {
   sendStringMessageToFlutter(data?.getStringExtra("roomName") ?: "default_value_when_null", "completeRoom")
}