Java

In Java, the getActiveCount() method is responsible for providing the number of tasks that are currently/actively running.

Generic graphs can be implemented with generic classes and HashMaps. They can store data of different types, such as int, string, custom objects, etc.

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.

The group() method of the Java Matcher class is used to extract the text that matched a regular expression from the string.

The Scanner “nextDouble()” method scans the next input token as a Double and throws InputMismatchException, NoSuchElementException, and IllegalStateException.

The Arithmetic Exceptions can be faced upon dividing a number by zero, or division of non-terminating big decimals and can be resolved via “try/catch” blocks.