Running multiple Java classes

Question

I am trying to run a code with multiple Java class files and a jar file which is from a library I downloaded. I compiled them with the following:

javac -cp "quickfixj-all-.jar" BTCCMarketDataRequest.java Bot.java

The Bot class has the main method and the BTCCMarketDataRequest file has a bunch of other methods in the class. I am not creating any packages.

How should I run it though? If I do: java Bot I get the following output:

Exception in thread "main" java.lang.NoClassDefFoundError: quickfix/Group
    at Bot.main(Bot.java:4)
Caused by: java.lang.ClassNotFoundException: quickfix.Group
    at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:323)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:268)
    ... 1 more

The compiled class (the one in the jar file could not be found, but why? I compiled it.

I am new to Java so I have no idea what's going on.

Thank you!

score 0 · Accepted Answer · answered Feb 21 '15 at 08:05

0

You need to add the classpath while executing the program as well.

java -cp .:quickfixj-all-.jar Bot

This assumes that the Bot class is in the default package and all the jar and .class dependencies are in the same directory.

answered Feb 21 '15 at 08:05

Ravi K Thapliyal

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Thanks! What if there are multiple jar files? – Luis Cruz Feb 21 '15 at 08:48
You have to list all the jar files then. To avoid that the main class is usually bundled into its own jar file which lists all of its dependencies using /META-INF/Manifest.mf file. – Ravi K Thapliyal Feb 21 '15 at 09:02
Ok cool. How do you specify multiple jar files? Do I seperate them with a semicolon or something? – Luis Cruz Feb 21 '15 at 09:34
1

With Java 1.6 and later you can use wildcards when specifying a classpath. http://stackoverflow.com/a/1237107/611819 – dnault Feb 21 '15 at 09:37
@dnault Thanks for the share. Luis if you're on Java 6+, can you try `java -cp .:./* Bot` and see if you're able to reference multiple jars? – Ravi K Thapliyal Feb 21 '15 at 09:51

Running multiple Java classes

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