没有主方法如何生成jar文件？

Question

I am using Eclipse to write my program. I have 9 classes and I'm using applet and there is no main method within my codes.

I have been told that I need to submit a "runnable Jar Archive including source code". Somehow when I try to export my program using the Eclipse export "Runnable Jar File", I cannot find the launch configuration of my program. It works perfectly fine within Eclipse but I just can't export a runnable Jar File.

Can someone tell me what is the problem please?

Kenny

Answer 1

The 'Launch Configuration' is just fancy language for a class with a main method - based on what you select the wizard will populate your runnable jar manifest with the following attribute:

Main-Class: example.MainClass

Of course, you can't actually have an executable jar without this entry. So to answer your question, you have to create a class with a main method in it. The logic in the main method should launch your GUI in standalone mode. Then run your 'Export Runnable JAR` wizard again and choose the class you created as the Launch Configuration.

Answer 2

i guess you meet some problem launching your jar

you can build your custom launcher by click 'Run configurations' , where put your jar in classpath

Answer 3

As far as I know an executable JAR needs a main method. In the manifest Main-Class tag only a class can be declared (no method) where the the main-class is located. Maybe the following code is a possible solution for you:

package CaesarCodePackage;


public class StartClass {


 public static void main(String [] args)
  {
     // create an object of type appletclass 
     AppletClass theApplet = new AppletClass();
     theApplet.init();   // invoke the applet's init() method
     theApplet.start();  // starts the applet

     // If the applet views something (this is optional)
     // Create a window (JFrame) and make applet the content pane.
      javax.swing.JFrame window = new javax.swing.JFrame("Caesar's Cipher");
      window.setContentPane(theApplet);
      window.setDefaultCloseOperation(javax.swing.JFrame.EXIT_ON_CLOSE);
      window.pack();              // Arrange the components.
      window.setVisible(true);    // Make the window visible.
    }
}

If you do not need a Frame for showing the applet only start it.

(Thanks to Haider M. al-Khateeb for the code)

Answer 4

Have you tried exporting the project as a JAR (Not runnable JAR).

I think ti will then let you specify your own MANIFEST file. With this you simply need to make sure the MANIFEST.mf file contains a MAIN-Class for the program. (You will need a main class for the JAR to run)

http://docs.oracle.com/javase/tutorial/deployment/jar/manifestindex.html

http://docs.oracle.com/javase/tutorial/deployment/jar/appman.html

eg

Main-Class: MyPackage.MyClass