java - Overriden implementations of equals() and compareTo() never got called -

i need able sort user objects based on first name , last name. overrided compareto() method part of comparable interface. however, when use collections.sort(users), users arraylist of user objects, overrided implementation of compareto() never gets called. similarly, overrided equals() check equality of various fields in user; name, address, email address, etc. overrided implementation never called either users.remove(thisuser). here code overriden methods:

public class user implements comparable<user> {     [other methods , fields go here]      @override     public int compareto(user auser) {         system.out.println("comparing.....");         return (this.lastname.compareto(auser.getlastname()) < 0 ? -1 :                  this.lastname.compareto(auser.getlastname()) > 0 ? 1 :                 this.firstname.compareto(auser.getfirstname()) < 0 ? -1 :                 this.firstname.compareto(auser.getfirstname()) > 0 ? 1 : 0);     }      @override     public boolean equals(object o) {         if(this.firstname == ((user) o).getfirstname() &&            this.lastname == ((user) o).getlastname() &&            this.email == ((user) o).getemail() &&            this.address == ((user) o).getaddress() &&            this.gender == ((user) o).getgender()) {                return true;         }         return false;    }     @override    public int hashcode() {        return super.hashcode();    } 

i adding entries calling: users.add(newuser), works fine. example, i'll add "john doe", "bert s", "al s", , "steven x", , remain in order added them in.

calling methods: when write entries file, first sort them: collections.sort(users);

when remove user: users.remove(thisuser);

both adding, deleting, , sorting each 1 line.

why won't either of these methods called users.remove() or collections.sort()?

equals call if hashcode differs

please check code, it's calling compareto,

 user  user1 = new user();         user1.setfirstname("testfirst");         user1.setlastname("testlast");         user  user2 = new user();         user2.setfirstname("testfirst1");         user2.setlastname("testlast1");         list<user> list = arrays.aslist(user1, user2);         collections.sort(list);   

output: comparing.....

public class user implements comparable<user> {     private string lastname;     private string firstname;      @override     public int hashcode() {         system.out.println("hashcode.....");         int result = lastname.hashcode();         result = 31 * result + firstname.hashcode();         return result;     }      @override     public int compareto(user auser) {         system.out.println("comparing.....");         return (this.lastname.compareto(auser.getlastname()) < 0 ? -1 :                 this.lastname.compareto(auser.getlastname()) > 0 ? 1 :                         this.firstname.compareto(auser.getfirstname()) < 0 ? -1 :                                 this.firstname.compareto(auser.getfirstname()) > 0 ? 1 : 0);     }      @override     public boolean equals(object o) {         system.out.println("equals.....");         if (this.firstname == ((user) o).getfirstname() &&                 this.lastname == ((user) o).getlastname()) {             return true;         }         return false;     }        public string getfirstname(){         return firstname;     }     public string getlastname(){         return lastname;     }     public void setfirstname(string firstname) {         this.firstname = firstname;     }      public void setlastname(string lastname) {         this.lastname = lastname;     }  }