如何在加载图像后更新总计数？

Question

我正在使用以下代码在 Flutter 应用程序中从图库中选取图像。选择应用程序后，我想更新 int variables，即 a 和 total，如代码所示，但是在执行相同的应用程序时，我面临如下所示的错误

方法

Future getImage1() async {
    print("get image");

    PickedFile image = await _picker1.getImage(source: ImageSource.gallery);

    if (image != null) {
      setState(() {
        final File file = File(image.path);
        avatarImageFile1 = file;
        isLoading1 = true;
         a=1;
          total = total +a;
        print(total);
      });
    }
  }

错误日志

[VERBOSE-2:ui_dart_state.cc(157)] Unhandled Exception: NoSuchMethodError: The method '+' was called on null. Receiver: null Tried calling: +(1) #0 Object.noSuchMethod (dart:core-patch/object_patch.dart:53:5) #1 _AddImageState.getImage1. (package:nextproject/addandeditrecipe/add_image.dart:70:25) #2 State.setState (package:flutter/src/widgets/framework.dart:1233:30) #3 _AddImageState.getImage1 (package:nextproject/addandeditrecipe/add_image.dart:65:7) #4 _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:779:19) #5 _InkResponseState.build. (package:flutter/src/material/ink_well.dart:862:36) #6 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:182:24) #7 TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:504:11) #8 BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:282:5) #9 BaseTapGestureRecog<…>

Answer 1

NoSuchMethodError: The method '+' was called on null.

这可能是因为“总计”变量。你在某处声明过吗？尝试先初始化它。如果它已经被初始化它可能不在函数的范围内。

如何在加载图像后更新总计数？

How to update total count after loading the image?

flutter

imagepicker