URI is not hierarchical exception when running application from JAR

Question

I've exported my Java console application to a Jar file, but when I run the jar and call code that parses in a JSON file I get a java.lang.IllegalArgumentException

Does anyone know why the exception is being thrown when I run the program as a JAR? The parsing works fine when the application is run from Eclipse.

This is the exact error that is output when I execute the jar file and call the code that parses the JSON file:

Exception in thread "main" java.lang.IllegalArgumentException: URI is not hierar
chical
        at java.io.File.<init>(Unknown Source)
        at gmit.GameParser.parse(GameParser.java:44)
        at gmit.Main.main(Main.java:28)

This is how the parsing is being done in my GameParser class:

public class GameParser {
    private static final String GAME_FILE = "/resources/game.json";
    private URL sourceURL = getClass().getResource(GAME_FILE); 
    private int locationId;

    private List<Location> locations;
    private List<Item> items;
    private List<Character> characters;

    public void parse() throws IOException, URISyntaxException {
        ObjectMapper mapper = new ObjectMapper();
       mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);

        try {                   
            // read from file, convert it to Location class
            Location loc = new Location();
            loc = mapper.readValue(new File(sourceURL.toURI()), Location.class);
            Item item = mapper.readValue(new File(sourceURL.toURI()), Item.class);
            GameCharacter character = mapper.readValue(new File(sourceURL.toURI()), GameCharacter.class);

            // display to console
            System.out.println(loc.toString());
            System.out.println(item.toString());
            System.out.println(character.toString());
        } catch (JsonGenerationException e) {
            e.printStackTrace();
        } catch (JsonMappingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

This is the folder structure of my project:

Answer 1

The call getClass().getResource(GAME_FILE); will return a URL relative to this class. If you are executing your program from a JAR file, it will return a URL pointing to a JAR file.

Files in java can only represent direct filesystem files, not the ones in zip/jar archives.

To fix it:

1. Try to use getClass().getResourceAsStream() and use that instead of Files or
2. extract the files into some directory and use File in the same way as you are trying now.