title: Override compareTo and sort using two strings
body: <p>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</p>
  <p><em>Collections.sort()</em></p>
  <p>it will sort them in by title follow by singer in ascending order.</p>
  <pre><code>Public class Album implements Comparable{
  
  private String title;
  private String singer;
  private double price;
  
  .....
  
  public int compareTo(){
  
  // How to
  
  }
  
  }
  </code></pre>