the guide says that one difference between Java and Apex is:

Inner classes and interfaces can only be declared one level deep inside an outer class.

Considering I know in Java what is an Inner class, an Interface and an Anonymous class, could you bring an example so to understand what "one level deep inside" means? My guess is that could be something regarding OOP and the structure of inherithance a class or is considering the level deep as a nested structure, so that an inner classes

EDIT: there is an idea of lambda class, please feel free to vote at this official link

the guide says that one difference between Java and Apex is:

Inner classes and interfaces can only be declared one level deep inside an outer class.

Considering I know in Java what is an Inner class, an Interface and an Anonymous class, could you bring an example so to understand what "one level deep inside" means? My guess is that could be something regarding OOP and the structure of inherithance a class or is considering the level deep as a nested structure, so that an inner classes

EDIT: there is an idea of Lambdas, please feel free to vote at this official link, if you are beginner, see how lambdas make the code more readable the code with this simple example

the guide says that one difference between Java and Apex is:

Inner classes and interfaces can only be declared one level deep inside an outer class.

Considering I know in Java what is an Inner class, an Interface and an Anonymous class, could you bring an example so to understand what "one level deep inside" means? My guess is that could be something regarding OOP and the structure of inherit a class or is considering the level deep as a nested structure, so that an inner classes

the guide says that one difference between Java and Apex is:

Inner classes and interfaces can only be declared one level deep inside an outer class.

Considering I know in Java what is an Inner class, an Interface and an Anonymous class, could you bring an example so to understand what "one level deep inside" means? My guess is that could be something regarding OOP and the structure of inherithance a class or is considering the level deep as a nested structure, so that an inner classes

EDIT: there is an idea of lambda class, please feel free to vote at this official link