Methods that return Collection type must never return a nullable object either as direct null or wrapped in an Optional. What to use for Collections? null or Optional?įor Collections we neither use Null nor Optionals. Remember that just because something is marked Optional doesn’t guarantee that the caller will not pass null.Since the author of the code knows which arguments are required and which are optional, it is always recommended to do the basic validations and throw Exception accordingly. do something., ()-> log.error('missing list')) I do want to catch in.

More formally, removes an element e such that. Using Java Optional: List myList.

While defining a method, it is recommended to annotate the required arguments as. Removes a single instance of the specified element from this collection, if it is present (optional operation).

So in this case: List stringList Collections. Hence making them as Optionals will force the developer to check and extract the value thereby making the code more safe and reliable the emptyList method has this signature: public static final List emptyList() That before the word List means that it infers the value of the generic parameter T from the type of variable the result is assigned to.

The class can also be said to extend Vector. In addition to the basic push and pop operations, the class provides three more functions of empty, search, and peek. The class is based on the basic principle of last-in-first-out. Since public methods can be used at several different parts of the code by many other developers, there are more chances of getting NullPointerException since many developers are lazy enough to not to write a null check on the returned values. Java Collection framework provides a Stack class that models and implements a Stack data structure. The LinkedList object supports functions common to all collections (such as size() or isEmpty()), and also provides its own API.Returning optional from private methods will add an extra layer of complexity for a straight forward task Since private methods are used within the same class, their return type can easily be read and understood.Never use Optional as a method argument.Use Optional when returning single object from public method.

• Use null when returning single object from private method // class public static boolean isEmpty(Collection<> collection).

In this short articles I will walk you through some tips and tricks on when to use Nulls and Optionals in your codes. While there are some codes that are bad and some codes that are good, There also exists some codes that turn bad in an attempt to make it good because of lack of sufficient knowledge.

Java collections isempty