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]

Make sure you have installed a GraalVM JDK. The easiest way to get started is with SDKMAN!. For other installation options, visit the Downloads section.

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.

Compile the application:
```
 javac -d build src/com/example/App.java
```
This produces the file App.class in the build/com/example directory.
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.
Create a native executable:
```
 native-image -jar App.jar
```
It will produce a native executable in the project root directory.
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.

Build a Native Executable from a JAR File

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