What error am I making with the ClassLoader getResources?

Question

I have written the following code to test a method within my code. To create the s3Event, I have a json file but when I use the class loader I am always returned a null exception. It could be possible I have the absolute path incorrect? I have attached an image to show the file pathway layout in case this is the mistake.

@Test
@DisplayName("Testing the handleRequest")
void testTheHandleRequest() throws URISyntaxException, IOException {
    ClassLoader classLoader = getClass().getClassLoader();
    File file = new File(Objects.requireNonNull(classLoader.getResource("s3Event.json")).toURI());

    S3Event s3Event = new ObjectMapper().readValue(file, S3Event.class);
    Context context = null;
    LambdaHandler lambdaHandler = new LambdaHandler();

    assertEquals ("Finished handleRequest()", lambdaHandler.handleRequest(s3Event, null));
}

Does this answer your question https://stackoverflow.com/questions/6608795/what-is-the-difference-between-class-getresource-and-classloader-getresource?answertab=votes#tab-top — Nagaraj Kandoor, May 05 '20 at 07:21
more ever I insist getResourceAsStream() method for performance standpoint. — Nagaraj Kandoor, May 05 '20 at 07:22

score 1 · Accepted Answer · answered May 05 '20 at 07:29

The only problem I could find is in the project structure. Maven supports the default ClassLoader resource behaviour for the default structure src/test/resources, whereas in your case the folder name is src/test/java/testResources, which requires additional configurations to be made either in POM or in program.

My project folder structure is given below,

@Test
@DisplayName("Testing on the classloader")
public void testOnClassLoader() throws URISyntaxException {
    ClassLoader cl = getClass().getClassLoader();

    File file = new File(Objects.requireNonNull(cl.getResource("sample.json").toURI()));

    if(file != null) {
        System.out.println("File found "+ file.getAbsolutePath());
        assertEquals(true, true);
    }       

}

Output:

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running JsonLoaderTest
File found ~\resource-access\target\test-classes\sample.json
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.139 sec

Results :

Tests run: 1, Failures: 0, Errors: 0, Skipped: 0

[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  7.007 s
[INFO] Finished at: 2020-05-05T12:51:02+05:30
[INFO] ------------------------------------------------------------------------

Hope this helps.

Thanks @Krish.Venkat - perfect answer! I'd changed the resources name and didn't realize the specific pathway was required by maven. Cheers. — Hywel Griffiths, May 05 '20 at 07:38

What error am I making with the ClassLoader getResources?

1 Answers1