REPL stands for the Read-Evaluate-Print Loop and, as the name states, it reads the command entered on the command line, evaluates it, prints the result of evaluation, and continues this process on any command entered.
All the major languages, such as Ruby, Scala, Python, JavaScript, and Groovy, have REPL tools. Java was missing the much-needed REPL. If we had to try out some sample code, say using SimpleDateFormat to parse a string, we had to write a complete program with all the ceremonies, including creating a class, adding a main method, and then the single line of code we want to experiment with. Then, we have to compile and run the code. These ceremonies make it harder to experiment and learn the features of the language.
With a REPL, you can type only the line of code that you are interested in experimenting with and you will get immediate feedback on whether...
