Export a Java Project in Eclipse Neon to Executable JAR with Manifest

This post shows how to Export a Java Project in Eclipse Neon to a JAR file. If the JAR (Java Archive) file contains classes with main methods that have a signature public static void main(String[] args), the Java application can then be executed with the java command.

• Using the Java Perspective, right-click on the Java Project node in the Package Explorer to open its context menu.

• Select Export and select the JAR file export wizard under the Java node and click Next.

• On the JAR File Specification form, set the export destination for the JAR file and click Finish.

• The JAR file, here named JARExportTest.jar is now available in the specified directory.

• In this example, the JAR file contains one Java class with one main method:

package com.pgx.java;

public class HelloWorld {

  public static void main(String[] args) {
    // TODO Auto-generated method stub
    String[] words = new String[] {"Hello ", "World", "!"};
    
    for (String s : words) {
      System.out.print(s);
    }
  }
}

• Open a terminal on Mac OS or open the command prompt on Windows and go to the JAR file location.

MyMac:Java Admin$ pwd
/Users/Admin/Desktop/Java
MyMac:Java Admin$ ls -lha *Export*.jar
-rw-r--r--  1 Admin  1368638373   1.7K Jan 13 16:18 JARExportTest.jar
MyMac:Java Admin$ 

• The HelloWorld main class can be executed with the following command:

java -cp JARExportTest.jar com.pgx.java.HelloWorld

• The output is shown in the console:

MyMac:Java Admin$ java -cp JARExportTest.jar com.pgx.java.HelloWorld

Hello World! 

• Above, the class HelloWorld containing the main method to execute is explicitly given in the java command.
• Alternatively, a Manifest file can be used to specify an application’s entry point.
• When exporting the JAR file, select Next on the JAR File Specification form.

• Click Next again on the JAR Packaging Options form.

• The next form will show the JAR Manifest Specification options.

• Check Save the manifest in the workspace and use the Browse button to set a location.
• Select the Main class, here it is HelloWorld using the Browse button.
• Finally, click in Finish to export the Java project to a JAR file that also contains a manifest file.
• The manifest file is automatically generated and included in the Java project in Eclipse Neon.

• The JAR file can now be executed without specifying a main method. The java command will pick the one provided in the manifest file. Make sure to use the option -jar instead of -cp.

java -jar JARExportTest.jar

MyMac:Java Admin$ java -jar JARExportTest.jar

Hello World! 

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