How to change textfield background color on focus

Question

I need to change textfield background color grey to white when user tap on textfiled. Focused textfield's background color should change grey to white and other un focused textfield background color stay remain grey.

i tried this

inputDecorationTheme: InputDecorationTheme(
        filled: true,
        fillColor: AppColors.textFieldBG,
        focusColor: AppColors.white,
        hintStyle: const TextStyle(color: AppColors.labelText, fontSize: 16),
        contentPadding:
            const EdgeInsets.symmetric(horizontal: 10, vertical: 20),

        focusedBorder: OutlineInputBorder(
            borderSide: const BorderSide(color: Colors.black26),
            borderRadius: BorderRadius.circular(10)),
        disabledBorder: OutlineInputBorder(
            borderSide: const BorderSide(color: Colors.transparent),
            borderRadius: BorderRadius.circular(10)),
        enabledBorder: UnderlineInputBorder(
          borderSide: const BorderSide(color: Colors.transparent),
          borderRadius: BorderRadius.circular(10),
        ),  

Here is text-filed code:

    TextField(
              focusNode: focusNode,
              onChanged: onChanged,
              controller: controller,
              maxLines: maxLines,
              onTap: onTap,
              enabled: isEnable,
              decoration: InputDecoration(
                  filled: true,
                  fillColor: AppColors.textFieldBG,
                  focusColor: AppColors.white,
                  hintText: hintText,
                  suffixIcon: isShowSuffixIcon
                      ? InkWell(
                          onTap: onTapIcon,
                          child: const Icon(
                            Icons.date_range_outlined,
                            color: AppColors.labelText,
                          ),
                        )
                      : null),
            ),

Answer 1

You can do something like this:

FocusNode _focusNode = FocusNode();
Color _color = Colors.grey;

@override
void initState() {
  _focusNode.addListener(() {
    if(_focusNode.hasFocus){
      setState(() {
        _color = Colors.white;
      });
    }
    else{
      setState(() {
        _color = Colors.grey;
      });
    }
  });
}

TextField(
  decoration: InputDecoration(
    fillColor: _color,
    filled: true
  ),
  focusNode: _focusNode,
),