[TAP5-1480] Couldn't create property conduits for generic interfaces

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 5.2
• Fix Version/s: 5.4
• Component/s: tapestry-ioc
• Labels: generics
• Assignee: Thiago Henrique De Paula Figueiredo
• Reporter: Ivan Khalopik
• Created: 20/Mar/11 19:01
• Updated: 28/Jun/14 21:01
• Resolved: 28/Jun/14 20:30

Description

Couldn't create property conduits for generic interfaces.

public class TestTapestry {
@Test
public void test()

{ final PropertyAccess access = new PropertyAccessImpl(); final ClassPropertyAdapter adapter = access.getAdapter(NamedEntity.class); }

public static interface Entity<T extends Serializable>

{ T getId(); }

public static interface NamedEntity extends Entity<Long>

{ String getName(); }

}

This test will throw an exception:

Caused by: java.lang.NullPointerException
at org.apache.tapestry5.ioc.internal.util.GenericsUtils.extractActualType(GenericsUtils.java:143)
at org.apache.tapestry5.ioc.internal.util.GenericsUtils.extractActualTypeAsClass(GenericsUtils.java:174)
at org.apache.tapestry5.ioc.internal.util.GenericsUtils.extractGenericReturnType(GenericsUtils.java:40)
at org.apache.tapestry5.ioc.internal.services.ClassPropertyAdapterImpl.<init>(ClassPropertyAdapterImpl.java:50)
at org.apache.tapestry5.ioc.internal.services.PropertyAccessImpl.buildAdapter(PropertyAccessImpl.java:99)
... 33 more

It is thrown because of this lines (GenericsUtils:140-143)

final Class descendantClass = asClass(descendant);
final ParameterizedType parameterizedType = (ParameterizedType) descendantClass.getGenericSuperclass();
extractedType = parameterizedType.getActualTypeArguments()[typeArgumentIndex];

It gets generic superclass, but it is null, there are only interfaces.

So it makes impossible to create property bindings for such beans.