Question

Lets say i’ve a Album class. How do i code the compareTo method so that when i’ve a ArrayList of Album object and i call

Collections.sort()

it will sort them in by title follow by singer in ascending order.

Public class Album implements Comparable{

private String title;
private String singer;
private double price;

.....

public int compareTo(){

// How to

}

}

Answer 1

public class Album implements Comparable<Album> {
   ...
   public int compareTo(Album other) {
     int cmp = title.compareTo(other.title);
     if (cmp == 0) {
       cmp = singer.compareTo(other.singer);
     } 
     return cmp;
   }
}