如何将 Text 变量的初始值提供给 Text Widget Flutter

Question

Into the circleAvatar from flutter before user put they own image I want to replace the space with the Initial value the first digit of the currentUser variable name into TextWidget. it means for example the Name is "john" I want to get "J" how we can reach that?

  
  final imageUrl = true;

and build method

imageUrl ? CircleAvatar(
                radius: 60,
                backgroundImage: AssetImage(currentUser.imageUrl),)
                  : CircleAvatar(backgroundColor: Colors.yellow,
                child: Text(currentUser.name[0]),),
              SizedBox(
                height: 60,
              ),

In this way I get it but I dont know how to if imageUrl is null return currentUser.name[0]

Answer 1

to get the first character of a name:

final s = "John";
print(s[0]); // => J

to guard against null, you can use the ?? or the ? operator.

to get a circle avatar with a character text widget as child instead of an image, depending on whether imageUrl is null or not:

imageUrl ? CircleAvatar(backgroundImage: NetworkImage(imageUrl),)
 : CircleAvatar(backgroundColor: Colors.brown.shade800,
    child: Text(currentUser && currentUser.isNotEmpty? currentUser[0] : "default"),)