Why can't I initialize an instance variable after it's been declared?

Question

Java

Why can I do this:

public class Main{
int a = 10;
}

But I can't do this:

public class Main{
int a;
a = 10;
}

?

Answer 1

A variable can be initialized, but not in the way you do.
Here you can read about the possible options: https://vertex-academy.com/tutorials/en/bloki-inic...

Answer 2

You are trying not to initialize a variable, but a class field. It can be initialized either within a method or when declared. But your initialization lies inside the class definition. And so it is impossible.