static base path to resource files

this works:

add resources folder at the same level as src, mark it as resources folder.

build.gradle:

sourceSets {
    main {
        java.srcDirs 'src'
        resources.srcDirs 'resources'
    }
}

assuming there is a dir "resources/img", path to files in this dir is:

public class Resource {
    public static String PathToImg(String name) {
        return "/img/" + name;
    }
}