Java 9 JShell

Jshell (developed in project Kulla) is a java shell allowing you to type java instructions at the shell prompt and have them executed.

• if jshell detects a complete statement even without a closing semicolon
• you can type an expression which will be evaluated 

-> 2 + 2
| Expression value is: 4
| assigned to temporary variable $1 of type int

• you are not obliged to catch exceptions
• you can save and load your command history
• you can use methods and references that will only be defined later

-> double volume(double radius) {
>> return 4.0 / 3.0 * PI * cube(radius);
>> }
| Added method volume, however, it cannot be invoked until method cube(double), and variable PI
are declared

• you can list current variables, methods...
•  tab completion as you type

Here's a small tutorial.