How to make jar file executeable ?

[benny rusli]

Hallo expert people,
i have made a jar file with the following command : jar cf backup.jar backup_pro.class backup_pro$zip.class ... and if i run with the following command : java -jar backup.jar , it will work but if i double click there is an error "Could not find the main class. Program will exit!". Have any one experience how to make jar file executeable with double click. I have download many jar files from internet and they are working with double click and "java -jar jarfiles.jar" command. Any Help will be appreciated.

[Yevgeniy Treyvus]

Sure,

You should write your own Manifest.mf file and force the Java Jar utility to use it with the -m command. Your Manifest.mf file should have an entry called "Main-Class" that points to the class in your application that has the

public static void main(String arg[])

method. An example Manifest.mf file would look like:

Manifest-Version: 1.2
Created-By: 1.4 (Sun Microsystems Inc.)
Main-Class: suncertify.swing.MainFrame

[benny rusli]

My MANIFEST.MF seems right as yours, here is the content of my Manifest file :

Manifest-Version: 1.0
Created-By: 1.4.1_01 (Sun Microsystems Inc.)
Main-Class: backup_pro

where backup_pro is the main class, the jar file that i create "backup.jar" work with the following command "java -jar backup.jar" but not with double click. What do you mean with -m ? can you give a complete command ? thank you very much.

[Yevgeniy Treyvus]

The -m command simply tells the Jar utility to package the Manifest.mf file you wrote within the Jar. An example command would look like:

jar cmf Sample.mf Sample.jar Sample.class Turtle.class Sample.java Turtle.java images

You can find a more complete exlanation in this tutorial:

http://www.cs.princeton.edu/introcs/85application/jar/jar.html

Make sure your Manifest.mf file is in the META-INF folder. An example structure would look like:

META-INF/
META-INF/MANIFEST.MF
Sample.class
Turtle.class
Sample.java
Turtle.java
images/
images/image1.gif
images/image2.gif
images/image3.gif

You can use something like Winzip to look at the contents of your Jar file. Make sure all needed .class files are indeed there.

[Stefan Wagner]

The manifest has to be correct, if you call 'java -jar xy.jar' too, shouldn't it?
So it shouldn't be the reason.

Suspicious, suspicious...

You're sure about the errormessage?