Order of jar and dir classpath items seems to impact runtime

[Eric Barnhill]

I have a simple code like so, which imports a single class

package com.ericbarnhill.getClassTest;
import org.apache.commons.numbers.complex.*;
public class GetClassTest {
    public static void main(String[] args) {
        double[] d = new double[3];
        Complex[] c = new Complex[3];
        System.out.println(d.getClass());
        System.out.println(c.getClass());
    }
}

and I can compile it like so (hopefully the references to a typical Unix maven repository will be familiar enough to everyone)

javac -d . -cp ~/.m2/repository/org/apache/commons/commons-numbers-complex/1.0-SNAPSHOT/commons-numbers-complex-1.0-SNAPSHOT.jar GetClassTest.java

where I link to the jar. But, when I run it something interesting happens. The following command, with jar followed by local directory dot, runs:

java -cp ~/.m2/repository/org/apache/commons/commons-numbers-complex/1.0-SNAPSHOT/commons-numbers-complex-1.0-SNAPSHOT.jar:. com.ericbarnhill.getClassTest.GetClassTest

with the output

class [D class [Lorg.apache.commons.numbers.complex.Complex;

which is correct. However this same command, with the dir dot and the jar path switched:

java -cp .:~/.m2/repository/org/apache/commons/commons-numbers-complex/1.0-SNAPSHOT/commons-numbers-complex-1.0-SNAPSHOT.jar com.ericbarnhill.getClassTest.GetClassTest

throws the following error:

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/numbers/complex/Complex at com.ericbarnhill.getClassTest.GetClassTest.main(GetClassTest.java:8) Caused by: java.lang.ClassNotFoundException: org.apache.commons.numbers.complex.Complex at java.net.URLClassLoader.findClass(URLClassLoader.java:381) at java.lang.ClassLoader.loadClass(ClassLoader.java:424) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335) at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ... 1 more

In otherwords, I think java is "giving up" after the dot and not looking for the jar for some reason. Is this expected behavior? Is there a principle here I need to understand?