限制 Flutter 中第一个字符为“0”

Question

Flutter中如何限制“0”不应该放在第一个字符text field？下面是 dart 代码示例。

TextField(
                                          inputFormatters: <TextInputFormatter>[
                                            FilteringTextInputFormatter.allow(
                                                RegExp("[0-9\u0660-\u0669]")),
                                          ],
                                          keyboardType: TextInputType.number,
                                          focusNode: _nodeText1,
                                          controller: mobileNumber,
                                          decoration: InputDecoration.collapsed(
                                              fillColor: TuxedoColor.whiteColor,
                                              hintText: "5xxxxxxxx"),
                                        ),

Answer 1

用这个 ：

   inputFormatters: <TextInputFormatter>[
                                FilteringTextInputFormatter.allow(
                                  RegExp(r'[0-9]'),
                                ),
                                FilteringTextInputFormatter.deny(
                                  RegExp(
                                      r'^0+'), //users can't type 0 at 1st position
                                ),
                              ],