Build a Native Executable from a JAR File

You can build a native executable from a class file, from a JAR file, or from a module. This guide demonstrates how to build a native executable from a JAR file.

To build a native executable from a JAR file in the current working directory, use the following command:

native-image [options] -jar jarfile [executable name]

  1. Prepare the application.

    • Create a new Java project named “App”, for example in your favorite IDE or from your terminal, with the following structure:

       | src | --com/ | -- example | -- App.java

    • Add the following Java code to the src/com/example/App.java file:

       package com.example; public class App { public static void main(String[] args) { String str = "Native Image is awesome"; String reversed = reverseString(str); System.out.println("The reversed string is: " + reversed); } public static String reverseString(String str) { if (str.isEmpty()) return str; return reverseString(str.substring(1)) + str.charAt(0); } }

      This is a small Java application that reverses a String using recursion.

  2. Compile the application:

     javac -d build src/com/example/App.java

    This produces the file App.class in the build/com/example directory.

  3. Create a runnable JAR file:

     jar --create --file App.jar --main-class com.example.App -C build .

    It will generate a runnable JAR file, named App.jar, in the project root directory: To view its contents, run the command jar tf App.jar.

  4. Create a native executable:

     native-image -jar App.jar

    It will produce a native executable in the project root directory.

  5. Run the native executable:

     ./App

The default behavior of native-image is aligned with the java command which means you can pass the -jar, -cp, -m options to build with Native Image as you would normally do with java. For example, java -jar App.jar someArgument becomes native-image -jar App.jar and ./App someArgument.