You can run a Java app from the command line like this.

or

The separator can be either a forward slash or a dot. But when you try to run the same Java class on Ant, the separator has to be a dot.

So, the following Ant script should work.

Here's the situation. I have a jar file, which is a library I need to use for an embedded Java application. Even though the embedded device only support Java 1.4, the library implements some 5.0 methods in org.w3c.dom.DOMImplementation. Because the same class is already in rt.jar for 1.4, just compiling a normal way doesn't work.