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

StackOverflow https://stackoverflow.com/questions/21138500

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?

Était-ce utile?

La solution

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.

Autres conseils

use below:

C:\src>java maps.TestClasses.TestSOM

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

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".

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