Jar文件的NoClassDefFoundError

Question

I understand there are lots of questions on this topic but none of them seem to apply very well to my situation. Basically I created a program with three class files, one of them called UserInterface.class that contains the main function. I made a Manifest.txt that contains Main-Class: shoppingCrawler.UserInterface with a carriage return. And then I did jar cfm shoppingCrawler.jar Manifest.txt *.class. This creates a jar file called shoppingCrawler.jar. However, when I did java -jar shoppingCrawler.jar I got

Exception in thread "main" java.lang.NoClassDefFoundError: UserInterface (wrong
name: shoppingCrawler/UserInterface)
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:621)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:12
4)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
        at java.net.URLClassLoader.access$000(URLClassLoader.java:56)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)

Could not find the main class: UserInterface. Program will exit.

Do you know what's wrong? Thanks!

Answer 1

What is the contents of your jar file? It appears to me that your class files are in the root directory, instead of being in the "shoppingCrawler" directory.

Answer 2

The Class UserInterface cannot be found in the package shoppingCrawler/UserInterface

You have the wrong classpath. Please take a look at your classpath, maybe you call the application from the wrong directory (if it is not paked into a jar-file). Or you did not include all needed classes in your jar.