when i am running a .jar file it is showing that "could not find the main class : program will exit" . but the same .jar file is running in other system .can you tell what is the problem with my system.
Ignore that message; the program that runs JAR files when you double click it, javaw, has terrible error handling and shows the same error message for any throwable that's being thrown by the main method. Open a command prompt, go to the folder where the JAR file is located, and use java instead: This will show the stack trace of the actual throwable. My guess is that it will be a NoClassDefFoundError, which would indicate you're missing a few JAR files on the class path.