Compiling multiple packages using the command line in Java with external Jars

Question

I have the following file structure that I need to compile using the command line. I have been using Eclipse all this while and it works fine in the editor.

/src
     /maps
          Structures/ (.java files) using a 3rd party external JAR file in E:\Lib\math.jar
          Util/ (.java files)
          TestClasses/ (.java files) Test.java is the main class

I compiled the above files using the following javac directive

C:\src\maps>javac -classpath E:\Lib\math.jar Util\*.java Structures\*.java TestClasses\*.java

This compiles without a problem and creates the relevant .class files.

However, when I try to run the main class using the following java directive

C:\src\maps>java TestClasses\TestSOM

I get the following exception

Exception in thread "main" java.lang.NoClassDefFoundError: TestClasses\TestSOM (
wrong name: maps/TestClasses/TestSOM)
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:791)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:14
2)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
        at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
        at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:472)

what is the correct way of executing the main class using the command line?

@thiago.lenz yeah thinking about it now. But I still need a command line version since the target environment requires it. — Synex
– Synex, Commented Jan 15, 2014 at 13:28
@chrylis unfortunately I don't have maven in the place I'm trying to run this program and I'm not allowed to — Synex
– Synex, Commented Jan 15, 2014 at 13:41

Santosh · Accepted Answer · 2014-01-15 14:07:58Z

2

Use the fully qualified name of the class AND include the libraries as well to avoid the runtime errors for the classes referenced

C:\src\>java -classpath .;E:\Lib\math.jar map.TestClasses.Test

Assuming that Test.java has main method as you mentioned.

edited Jan 15, 2014 at 14:07

answered Jan 15, 2014 at 13:29

Santosh

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4 Comments

Synex Over a year ago

I get the following error when I do that Error: Could not find or load main class maps.TestClasses.TestSOM

Andreas Over a year ago

The current directory should be included in the classpath as well, so that java can find your freshly compiled classes. e.g. java -classpath c:\src;E:\Lib\math.jar map.TestClasses.Test Consider compiling your sourcefiles into a separate directory. You can specify this with the -d switch from javac (see link )

Synex Over a year ago

Thank you @Andreas problem solved. But I do not know a way to give you credit for giving the correct answer since its a comment

Santosh Over a year ago

@Andreas, thanks for pointing it out. I have corrected the answer.

Rahul · Accepted Answer · 2014-01-15 13:22:56Z

0

use below:

C:\src>java maps.TestClasses.TestSOM

If your classes are inside the src dir. If any other change dir to that dir.

answered Jan 15, 2014 at 13:22

Rahul

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2 Comments

Rahul Over a year ago

Do you have your compiled classes in your src dir?

Rahul Over a year ago

As above your structure your main class is Test.java so you should use maps.TestClasses.Test

Chris Rodier · Accepted Answer · 2014-02-25 02:33:46Z

0

cd maps/TestClasses

java -classpath E:\Lib\math.jar;../Structures;../Util; Test

If your class is Test.java.

You should start off placing all of your classes in the same folder, will be easier to start your project. They need not be in separate folders, and when you do use separate folders, you want them to be in different "packages".

answered Feb 25, 2014 at 2:33

Chris Rodier

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