Invoke method in obj A from obj B

Question

hi;
I'ld like to know what is the diff btwn the invocation method as below (inv1 vs inv2), which is better and recommended, tq.
class book1 {
public void chap1() {
System.out.println("c1.");
class inv1{
book1.chap1();
class inv2{
private book1 b1 = new book1();
b1.chap1();
}

Answer 1

ok, thanks for the comments. anyway, i just want to
get the concept, which type of invocation is
recommended and the reason.Well, if stat1() is declared static then you have a choise. You can either access it as in inv1 or inv2. In that case the inv1 is recommended, because stat1() belongs to the class (book1) as a whole and not to any particular object (b1).
if stat1() is not declared static then you don't have have a choise. You have to access it as in inv2. That's the situation in your example and that's why inv1 doesn't work.
What I meant with my recommendation is that you should avoid static declarations. They have their proper uses but as a newbie it's easy to overuse them because they resemble the global variables you may be accustomed to from for example Basic and that doesn't lead to good OO.