Java - getClassLoader().getResource() driving me bonkers

Question

I have this test app:

import java.applet.*;
import java.awt.*;
import java.net.URL;
public class Test extends Applet
{

    public void init()
    {
     URL some=Test.class.getClass().getClassLoader().getResource("/assets/pacman.png");
     System.out.println(some.toString());
     System.out.println(some.getFile());
     System.out.println(some.getPath());

    }
}

When I run it from Eclipse, I get the error:

java.lang.NullPointerException
    at Test.init(Test.java:9)
    at sun.applet.AppletPanel.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)

Classpath (from .CLASSPATH file)

<classpathentry kind="src" path="src"/>

In my c:\project\src folder, I have only the Test.java file and the 'assets' directory which contains pacman.png.

What am I doing wrong and how to resolve it?

Answer 1

You don't need the slash at the start when getting a resource from a ClassLoader, because there's no idea of a "relative" part to start with. You only need it when you're getting a resource from a Class where relative paths go from the class's package level.

In addition, you don't want Test.class.getClass() as that gets the class of Test.class, which will be Class<Class>.

In other words, try either of these lines:

URL viaClass=Test.class.getResource("/assets/pacman.png");
URL viaLoader=Test.class.getClassLoader().getResource("assets/pacman.png");

Answer 2

I would do it this way:

final InputStream stream;

stream = Test.class.getResourceAsStream("assets/pacman.png");
System.out.println("Stream = " + stream);

"/assets/pacman.png" is an absolute location whle "assets/pacman.png" is a relative location.

Answer 3

Mr. Skeet, Please help!!! You suggested to TofuBeer that he use:

URL viaClass=Test.class.getResource("/assets/pacman.png");
URL viaLoader=Test.class.getClassLoader().getResource("assets/pacman.png");

But I have tried this type of thing and it's not working. I get the error "URI is not hierarchical" My code:

URL url = new URL(adminProps.getProperty(MyProperties.CUSTOMER_PROFILE_FORM_URL.getPropertyName()));
System.out.println("URL: " + url);
URI uri = url.getClass().getResource("/forms/PSS-F-00045-R01-CP.pdf").toURI();
System.out.println("URI: " + uri);
File cpForm = new File(uri);

My error:

URL: http://192.168.102.239/IncidentReportViewer/forms/PSS-F-00045-R01-CP.pdf
URI: jar:file:/home/kkennedy/NetBeansProjects/IRUtilities/dist/IRUtilities.jar!/forms
java.lang.IllegalArgumentException: URI is not hierarchical
/PSS-F-00045-R01-CP.pdf
        at java.io.File.<init>(File.java:363)
        at emailhandlingpackage.SendEmails.sendEmailToCustomer(SendEmails.java:113)   

Of course, the first 2 lines are from the System.out, but I can't figure out how to get this to work. I assumed that the problem was because I've got this in a static method and so I couldn't use "this" for reference. But it appears that you're suggesting that itsn't a problem. Any suggestions would be much appreciated. Thanks.