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Include Resources in a Native Executable

The following steps illustrate how to include a resource in a native executable. The application fortune simulates the traditional fortune Unix program (for more information, see fortune).

  1. 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.

  2. Save the following Java source code as a file named Fortune.java:

     import java.io.BufferedReader;
 import java.io.InputStreamReader;
 import java.util.ArrayList;
 import java.util.Random;
 import java.util.Scanner;

 public class Fortune {

     private static final String SEPARATOR = "%";
     private static final Random RANDOM = new Random();
     private ArrayList<String> fortunes = new ArrayList<>();

     public Fortune(String path) {
         // Scan the file into the array of fortunes
         Scanner s = new Scanner(new BufferedReader(new InputStreamReader(this.getClass().getResourceAsStream(path))));
         s.useDelimiter(SEPARATOR);
         while (s.hasNext()) {
             fortunes.add(s.next());
         }
     }
        
     private void printRandomFortune() throws InterruptedException {
         int r = RANDOM.nextInt(fortunes.size()); //Pick a random number
         String f = fortunes.get(r);  //Use the random number to pick a random fortune
         for (char c: f.toCharArray()) {  // Print out the fortune
           System.out.print(c);
             Thread.sleep(100); 
         }
     }
      
     public static void main(String[] args) throws InterruptedException {
         Fortune fortune = new Fortune("/fortunes.u8");
         fortune.printRandomFortune();
     }
 }

  3. Download the fortunes.u8 resource file and save it in the same directory as Fortune.java.

  4. Compile the Java source code: 
     $JAVA_HOME/bin/javac Fortune.java
  5. Build a native executable by specifying the resource path: 
     $JAVA_HOME/bin/native-image Fortune -H:IncludeResources=".*u8$"
  6. Run the executable image: 
     ./fortune

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