How to create a custom exception type in Java?

class WordContainsException extends Exception
{
      // Parameterless Constructor
      public WordContainsException() {}

      // Constructor that accepts a message
      public WordContainsException(String message)
      {
         super(message);
      }
 }

try
{
     if(word.contains(" "))
     {
          throw new WordContainsException();
     }
}
catch(WordContainsException ex)
{
      // Process message however you would like
}