Reading a resource file from within jar

Rather than trying to address the resource as a File just ask the ClassLoader to return an InputStream for the resource instead via getResourceAsStream:

InputStream in = getClass().getResourceAsStream("/file.txt"); BufferedReader reader = new BufferedReader(new InputStreamReader(in));

As long as the file.txt resource is available on the classpath then this approach will work the same way regardless of whether the file.txt resource is in a classes/ directory or inside a jar.

The URI is not hierarchical occurs because the URI for a resource within a jar file is going to look something like this: file:/example.jar!/file.txt. You cannot read the entries within a jar (a zip file) like it was a plain old File.

This is explained well by the answers to:

• How do I read a resource file from a Java jar file?
• Java Jar file: use resource errors: URI is not hierarchical

To access a file in a jar you have two options:

• Place the file in directory structure matching your package name (after extracting .jar file, it should be in the same directory as .class file), then access it using getClass().getResourceAsStream("file.txt")

• Place the file at the root (after extracting .jar file, it should be in the root), then access it using Thread.currentThread().getContextClassLoader().getResourceAsStream("file.txt")

The first option may not work when jar is used as a plugin.

I had this problem before and I made fallback way for loading. Basically first way work within .jar file and second way works within eclipse or other IDE.

public class MyClass {    public static InputStream accessFile() {        String resource = "my-file-located-in-resources.txt";        // this is the path within the jar file        InputStream input = MyClass.class.getResourceAsStream("/resources/" + resource);        if (input == null) {            // this is how we load file within editor (eg eclipse)            input = MyClass.class.getClassLoader().getResourceAsStream(resource);        }        return input;    }}