I'm using ant to build my build.xml file, it compiles ok, but then getting a runtime java.lang.NoClassDefFoundError when running the resulting jar via "java -jar my_jar.jar". It seems like this comes up a lot but none of the related questions' solutions worked for me.
My classpath for javac contains only "/usr/local/lib/libthrift.jar" and the main .java file imports a bunch of thrift packages such as org.apache.thrift.transport.TTransportException.
When I try running the program via:
java -jar MyClass.jar
, I get the error:
Exception in thread "main" **java.lang.NoClassDefFoundError**: org/apache/thrift/transport/TTransportException
Caused by: java.lang.ClassNotFoundException: org.apache.thrift.transport.TTransportException
at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$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: **MyClass**. Program will exit.
Here are the things I've tried so far that don't work:
adding a flag on the command line like "java -cp /usr/local/lib/libthrift.jar -jar my_jar.jar", the result is the same error as above
adding <attribute name="Class-Path" value="./:/usr/local/lib/libthrift.jar"/> inside my jar's manifest> tag, the result is the same error as above
adding -Xbootclasspath/a:/usr/local/lib/libthrift.jar:./ to the java command line. it solves the first error but a different error comes up:
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/log4j/Logger
at org.apache.thrift.transport.TServerSocket.(TServerSocket.java:36)
at MyClass.start(Unknown Source)
at MyClass.main(Unknown Source)
EDIT:
If I comment out the code that instantiates the missing classes but leave the imports, the code executes fine.
EDIT:
I moved my java classes to a server and referenced the MainClass with the server in the manifest attribute, but that didn't fix anything.
解決方案
Could not find the main class: MyClass
The error seems actually related to your MANIFEST which:
may not have a complete classpath Class-Path: see this HowTo
The best solution when you have a jar is to try to include the required jars into the manifest declaration.
Manifest-Version: 1.0
Class-Path:
customer_client.jar
mailer_client.jar
signon_client.jar
or may not define adequately the MainClass within your 'my_jar.jar'.
basedir="."
includes="**/*.class"
manifest="MANIFEST.MF"
/>
the needs to specify the full path (packages) of the MainClass, not just MainClass.
If your main class is in the default package (the unnamed package), I am not sure it can be referenced by the loader (see this SO question)
So move your JarRunner into a package, and declare it appropriately in the element.