How to Use the Java 10 JDK Command Line Tools

The Java 10 JDK offers several command-line tools for developers to use. Here’s an overview of some useful tools and related features:

1. JShell (Interactive Java REPL)

The jshell tool allows developers to experiment interactively by evaluating Java expressions, statements, and code snippets without the need to set up a complete program. It was introduced as part of JDK 9 but is also available in Java 10.

You can use JShell via:

Command line: Just type jshell in your terminal/command prompt.
IntelliJ IDEA: Open the JShell console through Tools > JShell Console in the IDE. This allows trying smaller snippets of code and experimenting interactively [1].

2. Java Compiler (`javac`)

The javac tool is the standard way to compile Java source code into bytecode. In Java 10, the --release flag can be used to ensure compatibility with earlier JDK releases.

Command:

javac --release <version> FileName.java

To compile your code:

Open a terminal.
Navigate to the directory containing the .java file.
Run the javac command followed by the file’s name.

3. Java Runner (`java`)

The java tool is used to execute compiled Java applications or scripts. Java 10 also supports temporary files and improved APIs for startup optimizations.

Command example:

java FileName

4. Java Flight Recorder and Other Tools

Java Flight Recorder is useful for profiling and analyzing runtime performance. In JDK 10, you need to enable UnlockCommercialFeatures if using the Oracle JDK.

For example:

java -XX:+UnlockCommercialFeatures -XX:StartFlightRecording=duration=60s,filename=myrecording.jfr MyApplication

This is useful for monitoring or debugging [4].

5. JLink

The jlink tool lets you create runtime images that include all the modules your application requires (introduced in JDK 9). With Java 10, improvements were made for better custom image creation.

Command example:

jlink --module-path <modules-path> --add-modules <module-name> --output <destination-folder>

This tool is handy when distributing lightweight application bundles. IDEs like IntelliJ IDEA also provide options to integrate it into Maven or Gradle builds [5].

6. Managing Executable Scripts

Create and run Java commands or files directly as scripts without needing to compile them. This concept started gaining traction with JDK 11’s “shebang” support but can also apply lightly to Java 10 for executable bundling purposes [6].

7. General IntelliJ IDEA Features for Java 10

IntelliJ IDEA helps users by automatically configuring and detecting Java 10 features, including modular programming. Several integrations for JDK tools like javac, java, and jlink make development smoother [7].