Reading from src/main/resources gives java.nio.file.InvalidPathException on command line (but works fine in Eclipse)

Question

I read the file src\main\resources\input.txt as follows

    String abslutefn = getClass().getClassLoader().getResource("input.txt").getFile().trim();
    Path path = new File(abslutefn).toPath(); 
    String lines = Files.readString(path);

Above works great from Eclipse. But when I build and run from command line it fails

mvn clean install
java -cp target\boolean.jar com.xx.yy.zz.App
Exception in thread "main" java.nio.file.InvalidPathException: Illegal char <:> at index 4: file:xyz
        at java.base/sun.nio.fs.WindowsPathParser.normalize(WindowsPathParser.java:182)
        at java.base/sun.nio.fs.WindowsPathParser.parse(WindowsPathParser.java:153)
        at java.base/sun.nio.fs.WindowsPathParser.parse(WindowsPathParser.java:77)
        at java.base/sun.nio.fs.WindowsPath.parse(WindowsPath.java:92)
        at java.base/sun.nio.fs.WindowsFileSystem.getPath(WindowsFileSystem.java:229)
        at java.base/java.io.File.toPath(File.java:2290)

I peek into jar file

jar -tf target\boolean.jar

I see input.txt file at the root (and there is no src\main\resources)

What can I do to ensure file loads correctly when I run from command line jar -tf target\stealthboolean.jar . I am thinking something needs to be done in pom.xml but I am not sure what it is

Answer 1

You cannot use Path and Files with resources.

The getFile() method of URL does not return a valid file name. It's only called getFile() because java.net.URL was written 25 years ago, when URLs usually referred to physical files on other machines.

You can, however, open a resource as a stream, and convert the bytes yourself:

String lines;
try (InputStream stream =
    getClass().getClassLoader().getResourceAsStream("input.txt")) {

    lines = new String(stream.readAllBytes(), StandardCharsets.UTF_8);
}