Question

我在 flutter 中使用了颜色选择器插件，但对话框或颜色选择器本身遇到了错误。这是颜色选择器对话框的代码：

Color selectedColor;
  double strokeWidth;

  void initState(){
    super.initState();
    selectedColor = Colors.black;
    strokeWidth = 2.0;
  }

  void selectColor(){
    showDialog(
        context: context,
        builder: (_)=>
        AlertDialog(
          title: const Text('Pick a color!'),
          content: SingleChildScrollView(
            child: ColorPicker(
              pickerColor: selectedColor,
              showLabel: true,
              onColorChanged: (color){
                this.setState(() {
                  selectedColor = color;
                });
              },

            ),
          ),
          actions: <Widget>[
            TextButton(
                onPressed: Navigator.of(context).pop,
                child: Text("Close")
            )
          ],
        )
    );
  }

这是我遇到的错误：

The following NoSuchMethodError was thrown building RawGestureDetector-[LabeledGlobalKey<RawGestureDetectorState>#f296e](state: RawGestureDetectorState#9ea30(gestures: <none>, behavior: opaque)):
The getter 'red' was called on null.
Receiver: null
Tried calling: red

The relevant error-causing widget was: 
  SingleChildScrollView file:///E:/nush/painting_app/lib/main.dart

Answer 1

使用调试器单步执行您的代码，看看“The getter 'red' was called on null”实际发生的时间。

在 null 上调用了 getter red

1 个答案: