Null Check Operator used on null value

I am creating a drawer in flutter but whenever I click on the menu to open it, I get a Null check operator used on a null value error. What could be wrong?

        final scaffoldKey = GlobalKey<ScaffoldState>(); // the scaffoldKay variable


         AppBar(
          leading: IconButton(
            onPressed: () {
              scaffoldKey.currentState!.openDrawer(); // Error Here
            },
            icon: Icon(
              Icons.menu,
            ),
          ),
          title: Text(
            'Title Here',
            
            align: TextAlign.center,
            family: 'Poppins',
            style: FontStyle.normal,
            shadow: 0,
          ),

I have read others with a similar issues but it seems this is unique.

CodePudding user response：

You should null check for scaffoldKey first:

onPressed: () {
    if (scaffoldKey.currentState != null) {
          scaffoldKey.currentState.openDrawer();
    }
},

and also make sure you pass the key to scaffold too, like this:

Scaffold(
  key: scaffoldKey,
  ...
)

CodePudding user response：

You should assign scaffoldKey to the property key of the Scaffold widget. It's going to be something like this:

return Scaffold(
  key: scaffoldKey,     // <- Here
  appBar: AppBar(
    leading: IconButton(
      onPressed: () {
        scaffoldKey.currentState!.openDrawer();
      },
      icon: Icon(
        Icons.menu,
      ),
    ),
    title: Text(
      'Title Here',
      align: TextAlign.center,
      family: 'Poppins',
      style: FontStyle.normal,
      shadow: 0,
    ),
  ),