Thread: Comparable Interface

Comparable Interface In Java?

public class CD implements Comparable 
{
private String title, artist;
private double cost;
private int tracks;
 
//--------------------------------------…
// Creates a new CD with the specified information.
//--------------------------------------…
public CD (String name, String singer, double price, int numTracks)
{
title = name;
artist = singer;
cost = price;
tracks = numTracks;
}
 
//--------------------------------------…
// Returns a string description of this CD.
//--------------------------------------…
public String toString()
{
NumberFormat fmt = NumberFormat.getCurrencyInstance();
 
String description;
 
description = fmt.format(cost) + "\t" + tracks + "\t";
description += title + "\t" + artist;
 
return description;
}
 
public int compareTo(Object o) 
{ 
CD other = (CD) o; 
int result = (this.title.compareTo(other.title) 
if (result == 0) 
{ 
result = (this.artist.compareTo(other.artist);
}
return result; 
}

Public class CDCollection
{
   private CD[] collection;
   private int count;
   private double totalCost;
 
   //-----------------------------------------------------------------
   //  Constructor: Creates an initially empty collection.
   //-----------------------------------------------------------------
   public CDCollection ()
   {
      collection = new CD[100];
      count = 0;
      totalCost = 0.0;
   }
 
   //-----------------------------------------------------------------
   //  Adds a CD to the collection, increasing the size of the
   //  collection if necessary.
   //-----------------------------------------------------------------
   public void addCD (String title, String artist, double cost,
                      int tracks)
   {
      if (count == collection.length)
         increaseSize();
 
      collection[count] = new CD (title, artist, cost, tracks);
      totalCost += cost;
      count++;
   }
 
   //-----------------------------------------------------------------
   //  Returns a report describing the CD collection.
   //-----------------------------------------------------------------
   public String toString()
   {
      NumberFormat fmt = NumberFormat.getCurrencyInstance();
 
      String report = "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n";
      report += "My CD Collection\n\n";
 
      report += "Number of CDs: " + count + "\n";
      report += "Total cost: " + fmt.format(totalCost) + "\n";
      report += "Average cost: " + fmt.format(totalCost/count);
 
      report += "\n\nCD List:\n\n";
 
      for (int cd = 0; cd < count; cd++)
         report += collection[cd].toString() + "\n";
 
      return report;
   }
 
   //-----------------------------------------------------------------
   //  Increases the capacity of the collection by creating a
   //  larger array and copying the existing collection into it.
   //-----------------------------------------------------------------
   private void increaseSize ()
   {
      CD[] temp = new CD[collection.length * 2];
 
      for (int cd = 0; cd < collection.length; cd++)
         temp[cd] = collection[cd];
 
      collection = temp;
   }
}

The problem is that I am adding a method from CD to another class COLLECTIONS using the compareTo from this method and I can't figure out. Here are the specs:

Add a findCD() method
It has two input parameters: title and artist.
This method returns the CD object that matches the title and artist.
It returns a null if no match is found.

Any help would be appreciated.