java - How to implement equals without exposing fields? -

let's have dog class has field private final int age , method public dog ageby(time time) returns new instance of dog every time invoked. dog class not immutable doesn't have get methods return it's age, in other words dog's contract doesn't allow him age (why? cause there no talking dogs), can 'bark', 'sleep' , other dog's stuff.

but dog can compared other dogs age. need override public equals(object o) method in dog class. problem there no way compare it, because can't access passed dogs age.

question: how implement equals method without exposing fields of object?

any method can access private fields of same class, can write equals accessing directly fields, without needs of getters.

here example:

public class point {     private int x;     private int y;      public point (int x, int y) {         this.x = x;         this.y = y;     }      public boolean equals(object obj) {        // test null, , type        ...        point p = (point) obj;        return x == p.x && y == p.y;     }