How to check for null in a single statement in scala

Question

In my scala code   QueueManager add getObject    where getObject is a method that returns an object of type QueueObject   def getObject   QueuObject         val response     some response     return response     Is there a way I can check for the response being null  while adding the QueueObject  I know I can do this   if  getObject    null      QueueManager add getObject    But I do not wish to add a level of indentation  Is there an operator that does that inline   Thanks

User · Accepted Answer

Try to avoid using null in Scala  It s really there only for interoperability with Java  In Scala  use Option for things that might be empty  If you re calling a Java API method that might return null  wrap it in an Option immediately   def getObject   Option QueueObject           Wrap the Java result in an Option  this will become a Some or a None    Option someJavaObject getResponse      Note  You don t need to put it in a val or use an explicit return statement in Scala  the result will be the value of the last expression in the block  in fact  since there s only one statement  you don t even need a block    def getObject   Option QueueObject    Option someJavaObject getResponse    Besides what the others have already shown  for example calling foreach on the Option  which might be slightly confusing   you could also call map on it  and ignore the result of the map operation if you don t need it    getObject map QueueManager add   This will do nothing if the Option is a None  and call QueueManager add if it is a Some   I find using a regular if however clearer and simpler than using any of these  tricks  just to avoid an indentation level  You could also just write it on one line   if  getObject isDefined  QueueManager add getObject get    or  if you want to deal with null instead of using Option   if  getObject    null  QueueManager add getObject    edit - Ben is right  be careful to not call getObject more than once if it has side-effects  better write it like this   val result   getObject if  result isDefined  QueueManager add result get    or   val result   getObject if  result    null  QueueManager add result

User · Answer

If it instead returned Option QueueObject  you could use a construct like getObject foreach   QueueManager add     You can wrap it right inline with Option getObject  foreach     because Option QueueObject  null  is None

User · Answer

Although I m sure  Ben Jackson s asnwer with Option getObject  foreach is the preferred way of doing it  I like to use an AnyRef pimp that allows me to write   getObject ifNotNull   QueueManager add        I find it reads better   And  in a more general way  I sometimes write  val returnVal   getObject ifNotNull   obj   gt    returnSomethingFrom obj    otherwise     returnSomethingElse         replacing ifNotNull with ifSome if I m dealing with an Option  I find it clearer than first wrapping in an option and then pattern-matching it    For the implementation  see Implementing ifTrue  ifFalse  ifSome  ifNone  etc  in Scala to avoid if      and simple pattern matching and the Otherwise0 Otherwise1 classes

User · Answer

Option getObject  foreach  QueueManager add

[scala] How to check for null in a single statement in scala?

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