JShell for prototyping
Try Java expressions interactively without creating files.
Code Comparison
✕ Java 8
// 1. Create Test.java // 2. javac Test.java // 3. java Test // Just to test one expression!
✓ Java 9+
$ jshell jshell> "hello".chars().count() $1 ==> 5 jshell> List.of(1,2,3).reversed() $2 ==> [3, 2, 1]
Why the modern way wins
Instant feedback
Type an expression, see the result immediately.
No files needed
No .java files, no compilation step.
API exploration
Tab completion helps discover methods and parameters.
Old Approach
Create File + Compile + Run
Modern Approach
jshell REPL
Since JDK
9
Difficulty
beginner
JDK Support
JShell for prototyping
Available
Widely available since JDK 9 (Sept 2017)
How it works
JShell is a Read-Eval-Print Loop for Java. Test expressions, experiment with APIs, and prototype code without creating files, compiling, or writing a main method. Tab completion and inline docs included.