When Dart 2.12 was shipped in Flutter 2 in March 2021, an important language feature was added that impacts how you should view null values for your variables, parameters and fields: this is the sound null safety.
Generally speaking, variables that have no value are null, and this may lead to errors in your code. If you have been programming for any length of time, you are probably already familiar with null exceptions in your code. The goal of null safety is to help you prevent execution errors raised by the improper use of null.
With null safety, by default, your variables cannot be assigned a null value.
There are obviously cases when you want to use null, but you have to explicitly allow null values in your apps. In this recipe, you will see how to use null safety to your advantage, and how to avoid null safety errors in your code.