open resource with relative path in Java

Question

In my Java app I need to get some files and directories.

This is the program structure:

./main.java
./package1/guiclass.java
./package1/resources/resourcesloader.java
./package1/resources/repository/modules/   -> this is the dir I need to get
./package1/resources/repository/SSL-Key/cert.jks    -> this is the file I need to get

guiclass loads the resourcesloader class which will load my resources (directory and file).

As to the file, I tried

resourcesloader.class.getClass().getResource("repository/SSL-Key/cert.jks").toString()

in order to get the real path, but this way does not work.

I have no idea which path to use for the directory.

Answer 1

I had problems with using the getClass().getResource("filename.txt") method. Upon reading the Java docs instructions, if your resource is not in the same package as the class you are trying to access the resource from, then you have to give it relative path starting with '/'. The recommended strategy is to put your resource files under a "resources" folder in the root directory. So for example if you have the structure:

src/main/com/mycompany/myapp

then you can add a resources folder as recommended by maven in:

src/main/resources

furthermore you can add subfolders in the resources folder

src/main/resources/textfiles

and say that your file is called myfile.txt so you have

src/main/resources/textfiles/myfile.txt

Now here is where the stupid path problem comes in. Say you have a class in your com.mycompany.myapp package, and you want to access the myfile.txt file from your resource folder. Some say you need to give the:

"/main/resources/textfiles/myfile.txt" path

or

"/resources/textfiles/myfile.txt"

both of these are wrong. After I ran mvn clean compile, the files and folders are copied in the:

myapp/target/classes 

folder. But the resources folder is not there, just the folders in the resources folder. So you have:

myapp/target/classes/textfiles/myfile.txt

myapp/target/classes/com/mycompany/myapp/*

so the correct path to give to the getClass().getResource("") method is:

"/textfiles/myfile.txt"

here it is:

getClass().getResource("/textfiles/myfile.txt")

This will no longer return null, but will return your class. I hope this helps somebody. It is strange to me, that the "resources" folder is not copied as well, but only the subfolders and files directly in the "resources" folder. It would seem logical to me that the "resources" folder would also be found under "myapp/target/classes"