Executing a java program from a jar

[Gsan Sangle]

Hi all,
I have a the following question :
i have a class that is wrapped up in a jar , the class has a main method.
the manifest file does not contain the "MainClass :" entry.
i want to exeute the class with main function.
Can any help me ?

[Christophe Verré]

java -jar myjar.jar myclass
(Make sure the CLASSPATH is set properly)

[Gsan Sangle]

my jre/bin folder does not contain the .java file...
how do i set the path var, n wat exactly should be it be set to ?

[Christophe Verré]

Let's say your JAR file is called "myjar.jar".
Let's say the class containing your main method is called "MyClass.class"

1. Go to the directory where myjar.jar is
2. Execute : java -cp . -jar myjar.jar MyClass

This will launch MyClass contained in myjar.jar
You don't need the java file.

[Gsan Sangle]

Got the following error :

Failed to load Main-Class manifest attribute from
c:\extJars\abc_classes.jar

The manifest file does not contain the req entry.
Can it still be executed without the entry ?

[Christophe Verré]

Oops sorry, I misread your post.
Yes, I think you'll have to add this entry into the manifest file.

[Joanne Neal]

If you don't have a MainClass entry in your manifest you can't use the -jar option. Just add the jar file to your class path.

java -cp myjar.jar MyClass