CODEWITHSUNDEEP
javaclassjar
Gray Adams
Gray Adams

Reputation: 4117

ClassNotFoundException - Makes No Sense

General Information

I am developing a plugin for Minecraft using Bukkit's API. I have to use Apache Commons NET library.

The Problem

I am getting a ClassNotFoundException once the JAR is run.

Resolution (RESOLVED)

I manually made my MANIFEST.MF file (set it to use my custom file when exporting the JAR) and put this inside of it:

Manifest-Version: 1.0
Class-Path: libs/commons-net-3.0.1.jar

Worked like a charm.

What I've Done

I created a folder in the Project Explorer within my plugin and named it "libs". I copied the .jar for the Apache Commons library into said folder.

I then right clicked my project, went to Java Build Path, Add JAR(s), MyPlugin > libs > the.jar

Once added, everything from within the coding works fine. All imports are read correctly and no issue arises.

Upon exporting the project, it is noticeably larger as the library is attached to the .jar

However

I get this error:

Caused by: java.lang.NoClassDefFoundError: org/apache/commons/net/ftp/FTPClient
at me.geekplaya.AdventureLobbies.FileUpload.upload(FileUpload.java:14)
at me.geekplaya.AdventureLobbies.AdventureLobbies.onCommand(AdventureLobbies.java:766)
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:40)
... 12 more
Caused by: java.lang.ClassNotFoundException: org.apache.commons.net.ftp.FTPClient
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:41)
at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:29)
at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
... 15 more

Screenshots

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.classpath

<?xml version="1.0" encoding="UTF-8"?>
<classpath>
    <classpathentry kind="src" path="src"/>
    <classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.6"/>
    <classpathentry kind="lib" path="/Users/gray/Applications/Java Workspace/Server/craftbukkit.jar"/>
    <classpathentry kind="lib" path="libs/commons-net-3.0.1.jar"/>
    <classpathentry kind="output" path="bin"/>
</classpath>

Upvotes: 2

Views: 5622

Answers (3)

Garrett Hall
Garrett Hall

Reputation: 30032

If you notice the line:

at java.lang.ClassLoader.loadClass(ClassLoader.java:423)

This is a line that is loading a class using reflection. Try to go to the source in your stack trace and find what class it is trying to load.

Upvotes: 1

Bob Kuhar
Bob Kuhar

Reputation: 11140

You want to scrutinize that stacktrace. java.lang.NoClassDefFoundError is not java.lang.ClassNotFoundException. I think it is finding all the classes that are in the commons-net-3.0.1.jar but commons-net-3.0.1.jar has some dependency that is not being met. Crack the commons-net-3.0.1.jar open and see if you can locate a .class to satisfy the org.apache.commons.net.ftp.FTPClient. If its not in there, you'll have to find out where it comes from (probably some other JAR) and get it on the classpath as well.

Upvotes: 3

Erlend Kildahl
Erlend Kildahl

Reputation: 5

im not a pro, but i would think you have to add it to the classpath.if you have already done that then the path to the c

Upvotes: -2

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