Max lines in custom flutter text field

Issue

I have a AppTextField in flutter app as follow:

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:intl/intl.dart' as intl;

class AppTextField extends StatefulWidget {
  final int maxLines;
  final String? title;
  final TextInputType? keyboardType;
  final bool autoFocus;
  final TextInputAction inputAction;
  final bool isSuffixIcon;

  AppTextField(
      {this.title,
      this.maxLines: 1,
      this.keyboardType,
      this.autoFocus: false,
      this.inputAction: TextInputAction.next,
      this.isSuffixIcon: false});

  @override
  State<StatefulWidget> createState() => AppTextFieldSate();
}

class AppTextFieldSate extends State<AppTextField> {
  String? text = '';

  bool isRTL(String text) {
    return intl.Bidi.detectRtlDirectionality(text);
  }

  @override
  Widget build(BuildContext context) => Container(
      child: TextField(
          textDirection: isRTL(text!) ? TextDirection.rtl : TextDirection.ltr,
          textInputAction: widget.inputAction,
          keyboardType: widget.keyboardType,
          autofocus: widget.autoFocus,
          style: Theme.of(context).textTheme.bodyText1,
          maxLines: widget.maxLines,
          decoration: InputDecoration(
            labelText: widget.title,
            suffixIcon: widget.isSuffixIcon
                ? Icon(Icons.check_circle, color: Theme.of(context).hintColor)
                : Container(),
          ),
          onChanged: (value) {
            setState(() {
              text = value;
            });
          }));
}

When I use maxLines in AppTextField, there is a problem!

AppTextField(maxLines: 5, keyboardType: TextInputType.multiline)

Only one character is entered in a line as follow picture:

My question is:

Why occur this problem and I how to resolve it?

Solution

I resolved it :) I must use null instead of Container in suffixIcon widget. Container widget make to problem.

 suffixIcon: widget.isSuffixIcon
                ? Icon(Icons.check_circle, color: Theme.of(context).hintColor)
                : null,

Answered By - Ehsan Kalali