Example below accesses inner class from outer class.

Java Code:
public class TestIt {
    public static void main(String[] args) {
        Outer outer = new Outer();
        outer.new Inner().hello();
        /*
        output :
        Hello from Inner()
        */
    }
}

class Outer {
    public class Inner {
        public void hello(){
          System.out.println("Hello from Inner()");
        }
    }
}