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https://issues.apache.org/jira/browse/UIMA-4919?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15275700#comment-15275700
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Richard Eckart de Castilho commented on UIMA-4919:
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Maybe `org.apache.commons.lang3.reflect.FieldUtils.getAllFieldsList(Class<?>)`
(or friends) from Apache Commons 3.x would serve your purpose.
> NPE when calling org.apache.uima.fit.internal.ReflectionUtil.getFields(
> Class<? extends Resource> clz ) on interface class.
> ---------------------------------------------------------------------------------------------------------------------------
>
> Key: UIMA-4919
> URL: https://issues.apache.org/jira/browse/UIMA-4919
> Project: UIMA
> Issue Type: Bug
> Components: uimaFIT
> Affects Versions: 2.2.0uimaFIT
> Environment: JDK: OpenJDK Runtime Environment (build
> 1.8.0_03-Ubuntu-8u77-b03-3ubuntu3-b03)
> OS: Ubuntu 16.04 LTS (Xenial Xerus)
> Reporter: Jose Tomas Atria
> Assignee: Richard Eckart de Castilho
> Priority: Trivial
> Attachments: UIMA-4919.patch
>
>
> org.apache.uima.fit.internal.ReflectionUtil.getFields( Class<? extends
> Resource> clz ) throws a NullPointerException when the given class object
> represents and interface class on the while test on line 59 because the call
> to java.lang.Class.getSuperclass() inside the while loop on line 62 returns
> null as per the [documented
> behaviour|https://docs.oracle.com/javase/8/docs/api/java/lang/Class.html#getSuperclass--]:
> "(getSuperClass()) returns the Class representing the superclass of the
> entity (class, interface, primitive type or void) represented by this Class.
> *If this Class represents either the Object class, an interface, a primitive
> type, or void, then null is returned*.", here:
> {code}
> public static List<Field> getFields(final Class<?> aClass) {
> Class<?> cls = aClass;
> final List<Field> fields = new ArrayList<Field>();
> while (!cls.equals(Object.class)) { // <- THROWS NPE.
> final Field[] flds = cls.getDeclaredFields();
> fields.addAll(Arrays.asList(flds));
> cls = cls.getSuperclass(); // <- RETURNS NULL
> }
> return fields;
> }
> {code}
> This situation can occur e.g. when doing:
> {code}
> Class<? extends Resource> api = f.getAnnotation( ExternalResource.class
> ).api();
> ReflectionUtil.getFields( api ) // <- throws NPE if api is an interface, i.e.
> always.
> {code}
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