[master] IndexOutOfBoundsException with generic superclass

[darylteo]

Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
        at java.util.ArrayList.rangeCheck(ArrayList.java:653)
        at java.util.ArrayList.get(ArrayList.java:429)
        at com.sebastian_daschner.jaxrs_analyzer.model.JavaUtils.getTypeVariables(JavaUtils.java:340)
        at com.sebastian_daschner.jaxrs_analyzer.model.JavaUtils.resolvePotentialTypeVariables(JavaUtils.java:433)
        at com.sebastian_daschner.jaxrs_analyzer.model.JavaUtils.getReturnType(JavaUtils.java:326)
        at com.sebastian_daschner.jaxrs_analyzer.analysis.results.JavaTypeAnalyzer.mapGetter(JavaTypeAnalyzer.java:196)
        at com.sebastian_daschner.jaxrs_analyzer.analysis.results.JavaTypeAnalyzer.lambda$analyzeClass$3(JavaTypeAnalyzer.java

Took me awhile to figure out what was happening. The type analyzer does not handle concrete subclasses of generic types. Not sure if this is fixable in its current state due to erasure but I'll give it another crack tomorrow.

Code fails to identify the generic return type of getData().

---

// lombok generating getters and setters
@Data
public abstract class Json<T> {
    private T data;
}

@Path("/resource")
@Produces("application/json")
public class SomeResource {
    @GET
    public Many findAll() {
       ...
    }

    public static class Many extends Json<List<ResourceEntity>> {
    }

---

Use case:

• standardised return types for all endpoints (success, errors, JSONAPI spec stuff etc.)
• concrete models for swagger spec (above generates nice class names like SomeResourceMany). Returning Json<List> leads to weird behaviour as well (separate issue for another time)

[darylteo]

Battled this for a day, can't see a really good out, due to shitty generics.

In the meantime, I've managed to stop the exception by using the following code:

    private static Map<String, String> getTypeVariables(final String type) {
        final Map<String, String> variables = new HashMap<>();
        final List<String> actualTypeParameters = getTypeParameters(type);
        final Class<?> loadedClass = loadClass(toClassName(type));
        if (loadedClass == null) {
            LogProvider.debug("could not load class for type " + type);
            return Collections.emptyMap();
        }

        final TypeVariable<? extends Class<?>>[] typeParameters = loadedClass.getTypeParameters();
        for (int i = 0; i < actualTypeParameters.size(); i++) {
            variables.put(typeParameters[i].getName(), actualTypeParameters.get(i));
        }
        return variables;
    }

JavaTypeAnalyzer does not pass in a generic signature for superclass, so while there are expected parameters (such as T), the type information is simply not in the classname after erasure.

I'll keep this in my local fixes for now. Let me know if you want a PR.

[darylteo]

@sdaschner just did another similar repro for this issue.

[sdaschner]

Looked further into it and of course you were right. Changed that line but we should in general add more generic tests, maybe in the system test project...

Thanks!

[darylteo]

Haven't really had the time to look into the system tests, sorry. Not really sure how it fits in with this repository (do I need to mvn install it and have mvn pick it up as a plugin or something?).

Being able to run the tests in intellij while I'm developing is easier for me currently obviously.

of course you were right

Thanks! I'm flattered ;)

[sdaschner]

The reason for the system test is that we don't want to loose any test scenarios in which we invested time. Running in the IDE is more productive, yes, but how about having some (temporary) tests in the IDE and then moving it to the system test project after fixing it -- as regression tests?

The system test project takes the Analyzer from either Maven central (snapshot) or your local version in your Maven repository. So if you build a new JAX-RS Analyzer version via mvn clean install that will be taken when you run the system test project with ./run-test.js.

Hehe, well deserved :)