class Foo {
int count; // Error
void bar() => count = 0;
}
Why I’m seeing an error when I’am already initializing it in the bar method? I could understand this error if count was marked final.
Solution
(Your code was fine before Dart 2.12, null safety)
With null safety, Dart doesn’t know if you actually assigned a value to count. Dart can see initialization in three ways:
1. At the time of declaration:
int count = 0;
2. In the initializing formals parameters:
Foo(this.count);
3. In the initializer list:
Foo() : count = 0;
So, according to Dart, count was never initialized in your code and hence the error. The solution is to either initialize it in 3 ways shown above or just use the late keyword which will tell Dart that you are going to initialize the variable later.
4. Use the late keyword:
class Foo {
late int count; // No error
void bar() => count = 0;
}
5. Make variable nullable:
class Foo {
int? count; // No error
void bar() => count = 0;
}
Source: StackOverflow.com
