java super class and sub class result

I have following java code.

class A{
	static {
		System.out.print("1 ");
	}
	A(){
		System.out.print("3 ");
	}
	{
		System.out.print("2 ");
	}
}
class B extends A{
	static {
		System.out.print("4 ");
	}
	B(){
		System.out.print("6 ");
	}
	{
		System.out.print("5 ");
	}
}
class Demo{
	public static void main(String args[]){
		new B();
	}
}

the result is above as following
1 4 2 3 5 6

this is include super class and sub class but I could not understand how is the result generating?

Think of it this way. You can't make an instance of the class until the class itself is initialized. The main method lies within Demo class with (Object -> Demo) which initializes those classes statically in that order. We are not creating an instance of demo since main is a static method, hence instance initialization blocks are not run for either at this time. Nothing is printed so it is less interesting here. Classes are initialized upon first access of the class

The next step is to identify that immediately in the main method we are requesting to create a B object. Hence we have to look at the B class dependency here is (Object -> A -> B). The static initialization blocks for Object would have been already run (if any) so we are left with A, then B.

After A Static Initialization Blocks

> 1

After B Static Initialization Blocks

> 1 4

Now since the request from new B(); is for an instance of B, we have to go through each of the parent-most class (Object -> A -> B) and run their instance initialization blocks in order, followed by any relevant Constructor methods code. Unlike with the static initialization blocks above, this will be done EACH time an instance is constructed. This is done on a class-by-class basis. This example is a simpler case where there is only one constructor per class. Note that initialization blocks precede constructors. Nothing prints from Object class so we can disregard that.

After A instance initialization Blocks:

> 1 4 2

After A constructor (pertinent to our request)

> 1 4 2 3

After B instance Initialization Blocks

> 1 4 2 3 5

After B Constructor (pertinent)

> 1 4 2 3 5 6