Why do we go for inner classes in java?

Question

why cant we inherit the classes instead of having inner classes.
what is the exact difference between the inner class and subclass.
can anyone please explain me with some examples

Answer 1

An inner class doesn't have any relationship with the outer class per se,
except for one thing: an instantiation of the inner class can refer to the
members of the instantiation of the outer class. One instantiation of the
outer class can have many instantiations of the inner class 'circling
around' it. Try to implement the following example using inheritance:public class Star {
     private String name;
     public Star(String name) { this.name= name; }
     public Planet addPlanet(String name) { return new Planet(name); }
     public class Planet {
          private String name;
          private Planet(String name) { this.name= name; }
          public Moon addMoon(String name) { return new Moon(name); }
          public class Moon {
               private String name;
               private Moon(String name) { this.name= name; }
               public String toString() { return name+" (circling around "+Planet.this+")"; }
          public String toString() { return name+" (circling around "+Star.this+")"; }
     public String toString() { return name; }
     public static void main(String[] args) {
          System.out.println(new Star("sun").addPlanet("earth").addMoon("moon"));
}kind regards,
Jos