[Flutter/dart] Check if late variable is initialized

What want to do

• There is a variable that remain unchanged once the initial value is determined.

• However, it cannot be determined yet when the constructor is called.

About such variable

• Define the variable with late final

• Check whether it has been initialized (at some timing), and if it has not, set the initial value (if you do not check, you will get an error of assigning a value to final)

In this case, I didn't know how to check whether it was initialized.

I thought I could just check if it was null, but even if I checked for null, if I referenced an uninitialized variable, a reference error occurred.

Solution

The official opinion seems to be that such checks should not be done.

https://dart.dev/effective-dart/usage#avoid-late-variables-if-you-need-to-check-whether-they-are-initialized

In this case, you can make it a nullable variable, set the initial value to null, and set the initial value if it is null.