java - Sorting a list of constructed objects alphabetically using collections.sort -

i need take collection of objects using compareto() command, , have these stored in list, , use collections.sort() command sort them alphabetically last name, first name if last name isn't strong enough, , print off entire list @ end.

this code have far:

package sortlab; import java.io.*; import java.util.*; public class sortlab {     public static void main(string[] args) throws exception {        file yousaiduseourrelativefilenameforstudentdata =              new file("c:/my192/sortlabproj/src/sortlab/student.data");        scanner sc = new scanner(yousaiduseourrelativefilenameforstudentdata);                arraylist<student> studentlist = new arraylist<student>();        while (sc.hasnextline()) {                       student teststudent = new student(sc.next(), sc.next(), sc.next());             sc.nextline();             studentlist.add(teststudent);        }     }  } 

and next class:

package sortlab; import java.util.*; class student implements comparable<student> {      private string first;     private string last;     private string address;      public student(string f, string l, string a) {         first = f;         last = l;         address = a;     }      @override     public int compareto(student other) {         if (last.hashcode() > other.last.hashcode()) return 1;         if (last.hashcode() < other.last.hashcode()) return -1;         if (first.hashcode() > other.first.hashcode()) return 1;         if (first.hashcode() < other.first.hashcode()) return -1;         return 0;     }  } 

first of add getters first , last name. try code:

@override public int compareto(student other) {     int result = l.compareto(other.getlastname());     if (result == 0) {         return f.compareto(other.getfirstname());     } else {         return result;     } } 

then add tostring() method student class:

@override public string tostring() {     return f+" "+l+", "+a; }