title: What is the purpose of FeedReaderContract and how to define inner class in OpenHelper Class
body: <p>I am learning SQLite in android. For SQLite I am reffering developer.android.com. But I got some Confusion while reading the code. They wrote <code>FeedReaderContract</code> constructor to prevent 
  instantiating the <code>FeedReaderContract</code> class but they don't define <code>FeedReaderContract</code> class anywhere and the relation between <code>FeedReaderContract</code> and <code>FeedEntry</code>. </p>
  
  <p><a href="http://developer.android.com/training/basics/data-storage/databases.html#DbHelper" rel="nofollow">Here's link</a> which I am referring to. I provide code. How can I define inner class in openhelper class. Could anybody suggest me the good way?.</p>
  
  <p>For example, this snippet defines the table name and column names for a single table:</p>
  
  <pre><code>public static abstract class FeedEntry implements BaseColumns 
  {
      public static final String TABLE_NAME = "entry";
      public static final String COLUMN_NAME_ENTRY_ID = "entryid";
      public static final String COLUMN_NAME_TITLE = "title";
      public static final String COLUMN_NAME_SUBTITLE = "subtitle";
      ...
  }
  </code></pre>
  
  <p>To prevent someone from accidentally instantiating the contract class, give it an empty constructor. </p>
  
  <pre><code> //Prevents the FeedReaderContract class from being instantiated.
  private FeedReaderContract() {}
  </code></pre>