CODEWITHSUNDEEP
javaclasspathclassloadermanifest
Peter Müller
Peter Müller

Reputation: 11

Java Classpath drives me crazy (Doesn't find my classes)

Okay, so I've got the following file tree:

<appfolder>
- MyApp.jar
- lib/
-    log.jar
-    someother.jar
-    someother.jar
-    someother2.jar
- config.properties
- otherfiles.extension

I've tried dozens of way to launch this application. MyApp contains the following 

MANIFEST.MF:
Manifest-Version: 1.0
Ant-Version: Apache Ant 1.8.3
Created-By: 1.7.0_06-b24 (Oracle Corporation)
Main-Class: myapp.Main
Class-Path: MyApp.jar lib/*

If I invoke java -jar MyApp.jar it always says none of the classes in lib/log.jar could be loaded.

Here is a part of the combinations I've tried:

- *.jar lib/*
- *.jar lib/*.jar
- *.jar ./lib/*.jar
- ./*.jar lib/*.jar
- *.jar ./lib/*.jar
- tbc

NOTHING worked. Java always tells me that it could not find the classes inside the lib/log.jar

My next attempt was to specify the classpath via the command line.

java -cp "MyApp.jar:lib/*" myapp.Main

But even that doesn't work. In this case Java says it could not find the myapp.Main class.

I guess I'm doing something completely wrong since nothing of the methods I've found worked. If I put the classes from lib/log.jar into myApp.jar and start it it'll work. But that can't be the solution.

Any ideas?

Edit: I don't want to name every single lib jar. I just want the ClassLoader to search the ClassPath for the needed classes. I've seen this so many times.

Upvotes: 1

Views: 2491

Answers (3)

Ivan Lutsenko
Ivan Lutsenko

Reputation: 11

I had the same problem.

The default class path is the current directory. Setting the CLASSPATH variable or using the -classpath command-line option overrides that default, so if you want to include the current directory in the search path, then you must include a dot (.) in the new settings.

oracle documentation

Upvotes: 1

paulsm4
paulsm4

Reputation: 121759

For Linux, you should be able to do something like this:

java -cp MyApp.jar:lib:someotherjar.jar myapp.Main

You can (optionally!) use "-jar" for a .jar that contains your "main", or you can add any combination of paths and jar files (.jar file with qualified path names) to your classpath.

Here's the Java documentation

And here's a somewhat better explanation

Upvotes: 2

Satya
Satya

Reputation: 8881

add lib directory to your classpath via system variables , or via 

SET CLASSPATH=%CLASSPATH%;MYAPP/LIB;.

and then do a java -jar MyApp.jar

Upvotes: 0

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