Optional.ofNullable() Method in Java is used for the implementation of both null and not null values. The optional.empty() method appears for the null values

To implement a callback function in Java, the approach involves creating a function as a first-class entity, which is then invoked from a second class.

The covariant return type in Java deals with non-primitive data types like arrays, lists, and classes. It makes the code look cleaner and more usable.

In Java, the “Instant.now()” method is used to get the current date and time. It uses the UTC clock to get the current instant.

Static import in Java has access to all static methods/fields. It works in such a way that all static data is imported without calling each class name separately.

To get a year from the date, the calendar class, Local Date class, String.split() method, and SimpleDateFormat class are used in Java

Tail recursion occurs when a recursive call is made and ends afterward and has nothing to perform after the completion of this recursive call.

ActionListener belongs to the “java.util.event” package. To handle user requests efficiently the action listener interface of Java has to be implemented.