Creating instance of inner class outside the outer class in java [duplicate]

Answer 1

In your example you have an inner class that is always tied to an instance of the outer class.

If, what you want, is just a way of nesting classes for readability rather than instance association, then you want a static inner class.

public class A {
    public static class B {
        int k;
        public B(int a) { k=a; }
    }
    B sth;
    public A(B b) { sth = b; }
}

new A.B(4);