Apache POI Java程序在IDE（Eclipse）中运行良好，但是当我尝试将其作为可运行的jar运行时遇到NoClassDefFoundError

Question

I got a very strange problem that my program runs in Eclipse but doesn't run well wen exported as a runnable jar. I am getting ClassNotFoundException .

C:\Users\43156557\workspace\CAF3_IDE\MFTRelease>java -jar MSDocWriter.jar
Exception in thread "main" java.lang.reflect.InvocationTargetException
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
        at java.lang.reflect.Method.invoke(Unknown Source)
        at org.eclipse.jdt.internal.jarinjarloader.JarRsrcLoader.main(JarRsrcLoa
der.java:58)
Caused by: java.lang.NoClassDefFoundError: org/dom4j/DocumentException
        at org.apache.poi.openxml4j.opc.OPCPackage.init(OPCPackage.java:149)
        at org.apache.poi.openxml4j.opc.OPCPackage.<init>(OPCPackage.java:136)
        at org.apache.poi.openxml4j.opc.Package.<init>(Package.java:54)
        at org.apache.poi.openxml4j.opc.ZipPackage.<init>(ZipPackage.java:81)
        at org.apache.poi.openxml4j.opc.OPCPackage.open(OPCPackage.java:220)
        at org.apache.poi.util.PackageHelper.open(PackageHelper.java:39)
        at org.apache.poi.xwpf.usermodel.XWPFDocument.<init>(XWPFDocument.java:1
11)
        at com.hsbc.glt.automation.test.mft.util.MSDocumentWriter.initializeDocu
ment(MSDocumentWriter.java:92)
        at com.hsbc.glt.automation.test.mft.util.MSDocumentWriter.main(MSDocumen
tWriter.java:70)
        ... 5 more
Caused by: java.lang.ClassNotFoundException: org.dom4j.DocumentException
        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 java.lang.ClassLoader.loadClass(Unknown Source)
        ... 14 more

C:\Users\43156557\workspace\CAF3_IDE\MFTRelease>

Answer 1

ClassNotFoundException usually depicts that JVM is not able to load the required class file from the defined classpath (either the path is not correct or the class / jar is not present at the path).

The Error in current scenario might be cause have missed to include the Dependency libraries when creating the jar file. Since on eclipse you have the class-path correctly including those its working perfectly.

Make sure that you check "Package Required Jar into generated JAR" , this will include the jar files automatically from your eclipse build path.

for detailed info this might come handy Include Dependent Jars in Executable Jar