REPL stands for Read-Eval-Print-Loop. It is a shell where the user types an expression, it's evaluated, and the result returned to the user. The main purpose of using REPL is to interact quickly with Java programs without creating a java file, compile it, and run it. JShell is very useful for ... Read More

The Optional class provides a container that may or may not contain a non-null value. It has been introduced in Java 8 to reduce the number of places in the code where a NullPointerException has generated. Java 9 added three methods: ifPresentOrElse(),  or(), and stream(), which helps us deal with default values.In ... Read More

Java 9 introduces the JShell tool for the Java Programming Language. This tool allows us to evaluate code snippets such as declarations, statements, and expressions. We will get the details about Java Version and Vendor, and also get the details about OS Version and Name by using the static method: getProperty() ... Read More

Flow API is official support for reactive streams specification since Java 9. It is a combination of both Iterator and Observer patterns. The Flow API is an interoperation specification and not an end-user API like RxJava.Flow API consists of four basic interfaces:Subscriber: The Subscriber subscribes to Publisher for callbacks.Publisher: The Publisher publishes ... Read More

JShell is an interactive java shell tool introduced in Java 9 and allows us to execute code snippets, and shows the result immediately without declaring the main() method like Java. It is a REPL (Read-Evaluate-Print- Loop) tool and runs from the command-line prompt. We can create variables, methods, classes, scratch variables, ... Read More

The main purpose of the JLink feature is to create our own Customized JRE. Usually, we run a program with the default JRE that has been provided by Oracle Corporation with 214 MB of size.For instance, a user wants to print a simple "Hello World" message as shown belowpublic class ... Read More

A module is a collection of code in the form of classes organized in packages and static resources such as property files or others. It provides the outside environment with all the information that can be required to use that module. The module descriptor is a key source of the module system, and it's compiled version of ... Read More

Http/2 is the newer version of the Http protocol. The improvements of Http/2 include focusing on how data is framed and transported between server and client. In this new version of the Http/2 protocol, separate classes have defined for the Http client, requests, and responses. The new API makes Http ... Read More

The varargs functionality has been introduced in Java to facilitate the creation of methods with a variable number of arguments without resorting to array-type parameters or overloaded versions of the same method.Before Java 9 versions, if vararg methods are used with generics, then there is a warning message. Even though not ... Read More

Yes, we can have private methods or private static methods in an interface in Java 9. We can use these methods to remove the code redundancy. Private methods can be useful or accessible only within that interface only. We can't access or inherit private methods from one interface to another interface or class.Syntaxinterface ... Read More