difference between class level instantiation vs method instantiation

Question

what is difference between following variable usages

public class A{

    B b= new B();

    public void doSomething()
    {
        b.callme();
    }
}
         


        

Answer 1

I was just trying out a similar scenario, but due to a mistake I created a scenario for recursion instead (StackOverflow error):-

public class Test{

Test t=new Test();
public static void main(String[] args) {
       Test t=new Test();
       System.out.println("Hello");
}
} 

I think it might be helpful to some for the conceptual purpose.