java relative path

Question

Using the snippet below throws me a null pointer exception, but i can't find the reason:

String path = ResourcesLoader.class.getResource("src/i3d/resourcesloader/libraries/lib.txt").toString();

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Am i using the getResources wrong? I even tried to enter the full path, like "D:\Workspace...", double backslashes, double forwardslashes but i get the exception of null pointer. The only thing i haven't tried is using java's path separator, but that shouldn't be a problem at this moment as it runs on Windows. What do i miss?

Thanks!

What about i3d/resourcesloader/libraries/lib.txt

nidhin
– nidhin

2012-02-27 14:28:25 +00:00
Commented Feb 27, 2012 at 14:28 — nidhin
– nidhin, Commented Feb 27, 2012 at 14:28
What happens if you remove the src part from your path?

user647772
– user647772

2012-02-27 14:29:19 +00:00
Commented Feb 27, 2012 at 14:29 — user647772
– user647772, Commented Feb 27, 2012 at 14:29

Community · Accepted Answer · 2015-06-10 14:05:55Z

3

getResource searches via the classloader, so typically and simplified in the classpath. The src folder is not in the classpath – it only exists for the build. Depending on your build system (ANT, Maven, IDE internal) a resources folder may be merged into the classpath. You put your resource directly into the source folder which will also work (if the build process copies all non-Java resources to the class output folder or if the source folder is used for the output of the generated classes).

/ is the root for your resources if you use absolute resource locations. It is equivalent to the root within the src folder. /i3d/resourcesloader/libraries/lib.txt would be the correct way to access the resource.

It would be nicer to separate the resources in a separate folder that is merged by the build tool (e.g. in Maven: /src/main/java, /src/main/resources).

edited Jun 10, 2015 at 14:05

CommunityBot

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answered Feb 27, 2012 at 14:41

Hauke Ingmar Schmidt

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3 Comments

MRM Over a year ago

/i3d/resourcesloader/libraries/lib.txt works just fine,thx.

MRM Over a year ago

...it looks like if i use /i3d/resourcesloader/libraries/lib.txt i can't pass the string to a file constructor because it acts like it creates an empty file, not linking with the existing one at that adress. Instead, if i use src/i3d/resourcesloader/libraries/lib.txt in the File constructor it reads the existing one. I'm confused!

Hauke Ingmar Schmidt Over a year ago

getResource returns an URL. Use this, don't toString it. Better yet: In most cases you can just use getResourceAsStream and don't need any manual work with file handles.

Marcelo · Accepted Answer · 2012-02-27 14:29:38Z

1

It seems you are using NetBeans?

Just create a folder called src\resources, get your files inside there, and call this.getClass().getResource("lib.txt");.

Netbeans will pack that properly when building and the resources will be in the main folder inside the jar, so you can get without having to specify their folder.

answered Feb 27, 2012 at 14:29

Marcelo

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1 Comment

MRM Over a year ago

i've tried your way but it does't seem to find the file;still null pointer. using the /i3d/resourcesloader/libraries/lib.txt works though.

Vlad · Accepted Answer · 2012-02-27 14:36:11Z

1

You should only provide relative path from your classloading point (ie without src):

String path = ResourcesLoader.class.getResource("/i3d/resourcesloader/libraries/lib.txt").toString();

answered Feb 27, 2012 at 14:36

Vlad

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