This gist contains quick notes for newer features/classes/etc in Java 8/11.

JavaLessons.md

Optional class

This class is introduced in Java 8.

Optional.ofNullable(.) - allows passed parameter to be null. Optional.of(.) - throws NullPointerException if passed parameter is null

optional.isPresent(.) - checks the value is present or not optional.orElse(.) - returns the value if present otherwise returns, the default value passed
optional.get() - gets the value, value should be present `optional.map(.).orElse(.);