Question

Is there a way for java program to determine its location in the file system?

Answer 1

You can use CodeSource#getLocation() for this. The CodeSource is available by ProtectionDomain#getCodeSource(). The ProtectionDomain in turn is available by Class#getProtectionDomain().

URL location = getClass().getProtectionDomain().getCodeSource().getLocation();
File file = new File(location.getPath());
// ...

This returns the exact location of the Class in question.

Update: as per the comments, it’s apparently already in the classpath. You can then just use ClassLoader#getResource() wherein you pass the root-package-relative path.

ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
URL resource = classLoader.getResource("filename.ext");
File file = new File(resource.getPath());
// ...

You can even get it as an InputStream using ClassLoader#getResourceAsStream().

InputStream input = classLoader.getResourceAsStream("filename.ext");
// ...

That’s also the normal way of using packaged resources. If it’s located inside a package, then use for example com/example/filename.ext instead.