Java jar can't access resources

Question

I need to execute a jar file which uses some files located in some subfolders.

For example the directory tree can be like this:

jar_root/
├── executable.jar
├── folder1/
│    └── required_file1.txt
│
├── folder2/
│    └── required_file2.txt
│
├── other_folder/
│   └── ...
└── other_file.txt

In this example executable.jar needs to access required_file1 and required_file2.

I need to execute the jar from another directory, so I tried this command:

java -cp /path/to/jar_root/ -jar /path/to/jar_root/executable.jar <options>

But what I got is a FileNotFoundException on required_file1 (I guess the same Exception will be raised for required_file2)

How can I make the jar work?

Note that I cannot modify the jar, so I can't use getResourceAsStream, as suggested by this (and other) answer(s).

I guess it is something like `File file = new File("folder1", "required_file1")` — user2340612, Oct 08 '15 at 13:27
Then you **don't** need to set the classpath. You need to set the **current working directory!** For example `cd jar_root && java -jar ...`. In the future, access resources correctly to avoid this pain. — Boris the Spider, Oct 08 '15 at 13:27
I feel stupid now :) unluckily I have been given this jar from third party and I need to use it as it is — user2340612, Oct 08 '15 at 13:29
I `baksmali`d it and actually it is `new File(folder1, "required_file1")`. @BoristheSpider's answer is right! — user2340612, Oct 08 '15 at 13:32
Either the person who wrote this code is incompetent or you should be able to set `folder1` - perhaps via a commandline option. — Boris the Spider, Oct 08 '15 at 13:35

score 2 · Accepted Answer · answered Oct 08 '15 at 13:33

It depends on how the code in the jar tries to access the files. If by relative path, that can only work if you start the program from the appropriate working directory, for example:

cd /path/to/jar_root/ 
java -jar executable.jar <options>

An alternative is to reference the files by absolute path, or relative from classpath instead of filesystem path.

Java jar can't access resources

1 Answers1