Question

i want to understand from the below code y the value of static variable b was not initialized and though the value was initialized in the constructor.

public class A {
       private static B b = null;
       public A() {
           if (b == null)
             b = new B();
       }

       public static void main(String[] args) {
           b.func();
       }
    }

Thanks
Punith

Answer 1

You never call the A() constructor.
main function is static, that means that it doesnt “belong” to an instance of A.
So when you enter main, no instance of A has been created so A constructor has never been called and b is still null.

You should get a NullPointerException if you run this code.

If you add
new A();
before the b.func(); then you will be okay (code will still be odd)