Design Patterns and Best Practices in Java

Additions to the Optional class

Java 8 gave us the java.util.Optional class to handle null values and null pointer exceptions. Java 9 added a few more methods:

• ifPresentOrElse: The method void ifPresentOrElse(Consumer<? super T> action, Runnable emptyAction) performs the given action if the Optional value is present; otherwise, emptyAction is performed. Let's take a look at a few examples:

//Example 1jshell> Optional<String> opt1= Optional.ofNullable("Val")opt1 ==> Optional[Val]//Example 2jshell> Optional<String> opt2= Optional.ofNullable(null)opt2 ==> Optional.empty//Example 3jshell> opt1.ifPresentOrElse(v->System.out.println("found:"+v),()->System.out.println("no"))found:Val//Example 4jshell> opt2.ifPresentOrElse(v->System.out.println("found:"+v), ...