jshell

Abstract

jshell is a useful utility tool that adds the Read-Eval-Print Loop (REPL) to Java. It allows developers to try Java language features interactively or to evaluate some expressions quickly. For example, it’s common for Java programs to write files to the system’s temporary directory. Sometimes you may want to check the temporary directory to verify the contents of created files. To get the path of the temporary directory, you need to get the value of the Java system property, java.io.tmpdir. You can do this by creating a simple Java program that has a main method to output the value, or you can use the Apache Groovy Console (http://groovy-lang.org/groovyconsole.html) to quickly run the code. But writing another Java program seems like overkill for simple tasks like this, and using Groovy Console requires that you downloaded and install Groovy. Neither approach seems ideal. Now you have a better choice in Java 9—jshell.