SizedBox in flutter has 0 argument? - flutter

Question

I'm a beginner at flutter. I'm practicing to make in Scaffold.
In my code, the last area that Sized Box has errors in child and elevation, and color.
I don't understand why they are used in not correctly, Could you explain that to me?
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
#override
Widget build(BuildContext context) {
return MaterialApp(
home:Scaffold(
appBar: AppBar(
backgroundColor: Colors.white,
leading: IconButton(
icon: Icon(Icons.menu, color: Colors.pink,),
onPressed: () {
print("menu button is clicked");
}
),
title: IconButton(
onPressed: () { print("이미지버튼 동작"); },
icon: Image.asset('assets/images/Slimer_by_shinrider-dcqaiza.webp')),
),
body: Container(
width: 100,
height: 200,
margin: EdgeInsets.all(5.0),
decoration: BoxDecoration(
color: Colors.pinkAccent,
border: Border.all(color: Colors.purple)
),
),
child: SizedBox(
height: 80, width: 100,
child: Card(
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(16.0)
),
),
elevation: 4.0,
color: Colors.red
)
)
);
}
}

Answer 1

You have closed Container and Card early on. Please check below against yours and use below to fix the issue.
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(
backgroundColor: Colors.white,
leading: IconButton(
icon: Icon(
Icons.menu,
color: Colors.pink,
),
onPressed: () {
print("menu button is clicked");
}),
title: IconButton(
onPressed: () {
print("이미지버튼 동작");
},
icon: Image.asset(
'assets/images/Slimer_by_shinrider-dcqaiza.webp')),
),
body: Container(
width: 100,
height: 200,
margin: EdgeInsets.all(5.0),
decoration: BoxDecoration(
color: Colors.pinkAccent,
border: Border.all(color: Colors.purple)),
child: SizedBox(
height: 80,
width: 100,
child: Card(
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(16.0)),
elevation: 4.0,
color: Colors.red)))));
}
}

Answer 2

your body is Container, which is only need 1 Widget as child.
if you want to use more than 1 Widget , you need to wrap your children that provide List<Widget> as their children.
such as : Column, Row , ListView, etc.
What you miss is you add 1 close bracket in your code
body: Container(
width: 100,
height: 200,
margin: EdgeInsets.all(5.0),
decoration: BoxDecoration(
color: Colors.pinkAccent,
border: Border.all(color: Colors.purple)
),
), <= here your error , you close your container , so your child not included inside the container.
remove what i notice above