I wrote a helper method for getting values of static fields of specified type via reflection. The code is working fine, but I am getting "raw use of parameterized class" warning on line:
final List<Collection> fields = getStaticFieldValues(Container.class, Collection.class);The issue is that type parameter T can be generic type. Is there way to rewrite method getStaticFieldValues to work around this issue?
Code listing:
import static java.util.Arrays.asList;
import static org.junit.Assert.assertEquals;
import java.lang.reflect.*;
import java.util.*;
import org.junit.Test;
public class GenericsTest { @Test public void test() { // Warning "raw use of parameterized class 'Collection'" final List<Collection> fields = getStaticFieldValues(Container.class, Collection.class); assertEquals(asList("A", "B", "C"), fields.get(0)); } private static <T> List<T> getStaticFieldValues(Class<?> fieldSource, Class<T> fieldType) { List<T> values = new ArrayList<>(); Field[] declaredFields = fieldSource.getDeclaredFields(); for (Field field : declaredFields) { if (Modifier.isStatic(field.getModifiers()) && fieldType.isAssignableFrom(field.getType())) { try { final T fieldValue = (T) field.get(null); values.add(fieldValue); } catch (IllegalAccessException e) { throw new RuntimeException("Error getting static field values"); } } } return values; } public static class Container<T> { public static Collection<String> elements = asList("A", "B", "C"); }
}1 Answer
in the definition of method getStaticFieldValues() change:
getStaticFieldValues(Class<?> fieldSource, Class<T> fieldType) ^^^to
getStaticFieldValues(Class<?> fieldSource, Class<?> fieldType) ^^^
