Avoiding nulls using Optional

Let me show you guys this code:

Is this boilerplate code familiar for you? Null checking everywhere.

To give some historical context, Tony Hoare - one of the giants of computer science - wrote, "I call it my billion-dollar mistake. It was the invention of the null reference in 1965. I couldn't resist the temptation to put in a null reference, simple because it was so easy to implement."

What can you do to prevent unintended null pointer exceptions ? You can be defensive and add checks to prevent null references like you see in the above code, or you can use one of the amazing stuffs of Java 8 like the Optional pattern. We are going directly to the action, let me show you some code!

1. Creating Optional objects
   
   An empty Optional.
   
   
   A non null Optional. If audioSystem were null, a NullPointerException would be thrown. Take it into account.
   
   
   Finally, you can create an Optional from a null reference. If audioSystem were null, the resulting Optional would be an empty Optional.
   
   
2. Do something if value present
   
   Instead of this
   
   
   better this (functional style).
   
   
   or you can use it the imperative way (not recommended)
   
   
3. Filter values using filter method
   
   Instead of this
   
   better this (using the class Predicate).
   
   
4. Extracting and transforming values using the map method
   
   Instead of this
   
   better this
   
   

The purpose of Optional is not to replace every single null reference in your codebase but rather to help design better APIs in which—just by reading the signature of a method—users can tell whether to expect an optional value. In addition, Optional forces you to actively unwrap an Optional to deal with the absence of a value; as a result, you protect your code against unintended null pointer exceptions.

Killing the nulls!