在TextFormField Flutter中聚焦时如何清空提示文本

Question

我想使TextFormField中的提示文本在聚焦字段时消失。但是提示文本不会消失，除非我在该字段中插入一个字符。我做了以下。当焦点集中时，如何使提示文本消失？谢谢！

Container buildTextField(bool isObscure, TextEditingController textEditingController, String hintText, bool onlyNumber) {
    return Container(
      width: double.infinity,
      height: 60,
      color: MyColors.primary,
      alignment: Alignment.center,
      child: Padding(
        padding: EdgeInsets.only(left: 15, right: 10),
        child: TextFormField(
          textAlign: TextAlign.center,
          keyboardType: onlyNumber ? TextInputType.number : TextInputType.text,
          decoration: InputDecoration(
            hintText: hintText,
            hintStyle: TextStyle(
              color: Colors.white,
              fontWeight: FontWeight.w600,
            ),
            border: InputBorder.none,
          ),
          style: TextStyle(
            color: Colors.white,
            decoration: TextDecoration.none,
            fontWeight: FontWeight.w600,
          ),
          obscureText: isObscure,
          controller: textEditingController,
        ),
      ),
    );
  }

Answer 1

改为使用labelText，

 TextFormField(
            controller: fullNameController,
            validator: (value) {
              if (value.trim().isEmpty) {
                return Lang.enterFullName;
              }
              return null;
            },
            decoration: InputDecoration(
              labelText: Lang.fullName,
              prefixIcon: Icon(Icons.person),
            ),
            keyboardType: TextInputType.text,
            textInputAction: TextInputAction.next,
          ),