JAVA

can we create a class inside a class in java

Yes you can

class OuterClass {
   class InnerClass {
   }
}

java class creation inside method

public class ASimplisticTCPFiniteStateMachine_FSM_ {
    public static void main(String[] args) {
        class Lmao_It_Exists {
            public void main() {
                System.out.println("Hello World");
            }
        }
        new Lmao_It_Exists().main();
    }
}