Determine the absolute path of a jar file in classpath

[Arun R. S. Chandran]

hi,

Is there any way to determine the absolute path of jar file within the class path. If anybody knows, Please tell me how to do this?

Thanks,
Arun

[Wouter Oet]

You can get the classpath like this:

System.out.println(System.getProperty("java.class.path"));
System.out.println(System.getProperty("java.ext.dirs"));
System.out.println(System.getProperty("java.library.path"));    

[Rob Spoor]

Officially you can't, but a few hacks can help you out. One of them uses ProtectionDomain, search Javaworld.com for the article. The other one uses the fact that with most class loaders you can use the .class file itself as a resource. For instance, try this:

URL url = String.class.getResource("String.class");
System.out.println(url);

If the class file is located in a JAR file cut off the leading "jar:" and everything after the !. What remains is a URL to the JAR file. If the class file is located in a folder cut off the full class name with / instead of . (e.g. java/lang/String.class).

To convert the remaining URL to a File the following code can help you:

URL url = new URL(remainingString);
File file = new File(url.toURI());

That will only work if the remainingString is a URL with protocol "file".

[Zon Horn]

Here's upgrade to other comments, that seem to me incomplete for the specifics of:
- using a relative "folder" outside .jar file (in the jar's same location).

    String path = YourMainClassName.class
           .getProtectionDomain().getCodeSource().getLocation().getPath();
    path = URLDecoder.decode(path, "UTF-8");
    BufferedImage img =
           ImageIO.read(new File((new File(path).getParentFile().getPath())
           +  File.separator + "folder" + File.separator + "yourfile.jpg"));