User-defined objects in collections

[Sharda Vajjhala]

I have a program as follows:

import java.util.*;
 
class Address{
    private String name;
    private String street;
    private String city;
    private String state;
    private String zipcode;
    
    Address(String n, String s, String c, String st, String z){
       name = n;
       street = s;
       city = c;
       state = st;
       zipcode = z;
    }
}
 
class MailList{
    public static void main(String args[]){
       LinkedList ml = new LinkedList();
       
       //Store user-defined objects 
       ml.add(new Address("John Doe","123 Street","Sacramento","CA","95758"));
       ml.add(new Address("Jane Doe","234 Street","Anywhere","NJ","95670"));
       ml.add(new Address("Tarzan","Robin Ct","Toronto","MI","12345"));
       ml.add(new Address("Jane Doe","234 Street","Anywhere","NJ","95670"));
       
       System.out.println("Mailing list is:");
       Iterator itr = ml.iterator();
       while(itr.hasNext()){
          Object element = itr.next();
          System.out.println(element +"\n");
       }   
    }
}

This prints out as follows:
Mailing list is:
Address@f56cf041
Address@f574f041
Address@f624f041
Address@f634f041
Why does it not print out the address contained within the element? It prints out the actual elements, if I use simple objects such as Strings
such as the following example:

/* Iterator eg  */
 
import java.util.*;
 
class IteratorEg{
   public static void main(String args[]){
      LinkedList al = new LinkedList();
      
      al.add("C");
      al.add("U");
      al.add("C");
      al.add("K");
      al.add("O");
      al.add("O");
      
      Iterator itr = al.iterator();
      while(itr.hasNext()){
         Object element = itr.next();
         System.out.print(element + " ");
      }
      System.out.println();
  }
}

Output of this is as follows:
C U C K O O
I would have expected the 1st MailingList program to print out the actual addresses(although not formatted properly).
Can anyone please explain?
Thanks
Sharda[ edited to preserve formatting using the [code] and [/code] UBB tags -ds ]
[ July 30, 2002: Message edited by: Dirk Schreckmann ]

[Snigdha Solanki]

That's because your address class does not override toString() method of Object Class.The toString method for Object class returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object.
For example - Address@f56cf041

[Stu Glassman]

When you output a class, the program actually calls MyClass.toString(). The Object class defines toString as returning ClassName@hashcode. In order to output the Address correctly add the following method:

public String toString() {
   return name + "\n" +
      street + "\n" +
      city + ", " + state + " " + zipcode;
}

Feel free to change the code to produce whatever formatting you'd like.
-Stu

[venkatesh Nayak]

use like this

use getter and setter for accessing the private data member of a class.

then use foreach loop to display
for(Address adr:m1)
{
System.out.println(adr.getname());
System.out.println(adr.getstreet());
System.out.println(adr.getcity());
System.out.println(adr.getstate());
System.out.println(adr.getzipcode());
}

[Campbell Ritchie]

Welcome to the Ranch

You realise this is an 11‑year old thread? That technique would work well, however.
You should always use the code button. I thought of editing your post with the code button because the code looks much better, but you hadn't indented the code. We have some suggestions about indenting here. If you are quick, you can use the button to indent your code and add code tags for yourself.