How to read a file from a java class, both are in the same jar

Question

I have following structure in jar

myjar.jar -> com -> MYProgram.class

  -> file.txt 

In MYProgram i am trying to do:

getClass().getResourceAsStream("../file.txt")

I am getting NullpointerException when i try to read the inputstream..

Where is it going wrong ?

Answer 1

Either use

getClass().getResourceAsStream("/file.txt")

or

getClass().getClassLoader().getResourceAsStream("file.txt")

( ClassLoader.getResourceAsStream always takes an "absolute" resource name.)

I don't believe navigating up the "directory hierarchy" works in getResourceAsStream - the path either has to be relative to the given class but without navigating back up the tree, or it has to be absolute to start with.

Answer 2

Try the absolute path:

getClass().getResourceAsStream("/file.txt")

The Javadoc for getResourceAsStream says:

• If the name begins with a '/' ('\/'), then the absolute name of the resource is the portion of the name following the '/'.

• Otherwise, the absolute name is of the following form:

    modified_package_name/name 

  Where the modified_package_name is the package name of this object with '/' substituted for '.' ('\.').

This would turn your path into this absolute path:

/com/../file.txt

I don't think the .. notation is respected. It literally looks for the above absolute path.