his page tells you all you need to know about sorting collections, such as ArrayList.
Basically you need to
make your Contact class implement the Comparable interface by
creating a method public int compareTo(Contact anotherContact) within it.
Once you do this, you can just call Collections.sort(myContactList);,
where myContactList is ArrayList (or any other collection of Contact).
There's another way as well, involving creating a Comparator class, and you can read about that from the linked page as well.
Example:
public class Contact implements Comparable {
....
//return -1 for less than, 0 for equals, and 1 for more than
public compareTo(Contact anotherContact) {
int result = 0;
result = getName().compareTo(anotherContact.getName());
if (result != 0)
{
return result;
}
result = getNunmber().compareTo(anotherContact.getNumber());
if (result != 0)
{
return result;
}
...
}
}