Question

I’m making a java application that uses Javamail, and it works great when I compile it. I want to make it into a jar file so it can be easily moved around and executed. The problem is I am getting this error when I try to run the jar from the cmd line

java -jar ActriveTray2.jar

Exception in thread "main" java.lang.NoClassDefFoundError: javax/mail/Store
        at stockApp.init(stockApp.java:11)
        at ActiveTray.main(ActiveTray.java:31)
        Caused by: java.lang.ClassNotFoundException: javax.mail.Store
        at java.net.URLClassLoader$1.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)

Here’s what’s in my jar file

• images/tray.gif
• META-INF/MANIFEST.MF
• ActiveTray.class
• ActiveTray.java
• config.class
• config.java
• GmailFetch.class
• GmailFetch.java
• stockApp$1.class
• stockApp.class
• stockApp.java

I think the issue is classpath, where the jar doesn’t know where the javamail jar lives. My classpath is set correctly when I execute the code (java ActiveTray2) it works fine… help 🙁

Answer 1

you need to add the jars you depend on to the manifest file, and also add them to the jar you are creating. java -jar will ignore your environment’s classpath, by design.
From the java docs:

-jar: When you use this option, the JAR file is the source of all user classes, and other user class path settings are ignored.

so, you can add a line to your manifest file like:

Class-Path: mail.jar

to your manifest file.