Flutter 中带有容器小部件的 If 语句

Question

I created a condition so that if the value is different from null I want the container with that information to appear, if the value is null I don't want to show anything but the problem is that a null text is appearing instead. What can be happening?

@override
  Widget build(BuildContext context) {
return Scaffold(
          backgroundColor: Colors.white,
          body: Column(
            children: [
            Container(
                child: ("$_info" != null)
                    ? Container(
                        padding:
                            EdgeInsets.symmetric(horizontal: 20, 
                            vertical: 35),
                        child: Text(
                          "$_info",
                          textAlign: TextAlign.center,
                          style: TextStyle(
                              fontFamily: 'Montserrat',
                              fontSize: 14,
                              fontWeight: FontWeight.w500),
                        ),
                      )
                    : Container(),
                 ),
               ],
              ),
             };

Answer 1

You shouldn't create a new String from _info and test if it's different from null as in

"$_info" != null

This is always going to be true, because all Strings are different from null. So you're going to see the text "null" appearing on the screen because you have Text("$_info") later on.

Instead, you should just test if _info itself is different from null. So:

_info != null