Introspector mixes property types in IndexedPropDesc's w/ inherited info

Name: nt126004 Date: 01/04/2002


java version "1.4.0-beta3"
Java(TM) 2 Runtime Environment, Standard Edition (build
1.4.0-beta3-b84)
Java HotSpot(TM) Client VM (build 1.4.0-beta3-b84, mixed
mode)


Full Operating System Version :

GLibC 2.1.3, kernel 2.2.12, RHL 6.1


A description of the problem :
Under some circumstances, it is possible for Introspector to
create an IndexedPropertyDescriptor which has inconsistent
types for the regular and indexed versions of the accessor.

Specifically: if a superclass provides an indexed property
with an indexed getter and a subclass provides a nonindexed
getter with the same name, an IndexedPropertyDescriptor will
be created by the default Introspector which has
inconsistent property types for PropDesc.getPropType vs.
IdxdPropDesc.getIdxdPropType.

Originally observed in NetBeans IDE. A class extending
JPanel had a method public Component getComponent (to
implement some random interface). Selecting the source and
choosing Customize Bean, which is supposed to open a
property sheet permitting its properties to be edited and an
instance serialized, threw an exception: reported as #17728
on www.netbeans.org and worked around (see below). The
problem was that Container.getComponent(int) and Component
org.netbeans.core.ui.IDESettingsPanel.getComponent() were
mashed into the same (indexed) prop desc; the property sheet
code in NetBeans saw an IndexedPropertyDescriptor with a
getPropertyType, assumed it would be an array type according
to the JavaBeans spec, and tried to use it an array, and
failed.

Including simpler test case showing that the two types need
not be related. Here Date B.foo is unrelated to the indexed
int A.foo[]. It is a bug in Introspector to put them both in
the same property. Since a bean can have only one property
with a given name, it ought to hide int A.foo[] and return a
plain PropertyDescriptor, type Date, name foo, getter public
Date B.foo(), no setter.

#4477877 reported a number of problems with Introspector,
but these had to do with unreproducible load order. This is
different, it is reproducible as far as I know. #4168833 is
very similar, but not identical, to this bug.

Occurs in both 1.3.1_01 and 1.4 beta 3.

Steps to follow to reproduce the problem :
1. Compile and run the included test class.

Expected versus actual behavoir :
Actual results:

---%<---
prop: class<class java.lang.Class>
public final native java.lang.Class
java.lang.Object.getClass()
null
indexed prop: foo<class java.lang.String>
public java.lang.String Test17728$A.getFoo(int)
null
regular prop info also:
prop: foo<class java.util.Date>
public java.util.Date Test17728$B.getFoo()
null
---%<---

Expected results:

---%<---
prop: class<class java.lang.Class>
public final native java.lang.Class
java.lang.Object.getClass()
null
prop: foo<class java.util.Date>
public java.util.Date Test17728$B.getFoo()
null
---%<---


This bug can be reproduced always.

---------- Begin Source ----------
import java.beans.*;
import java.util.Date;
public class Test17728 {
    public static void main (String args[]) throws Exception
{
        BeanInfo y = Introspector.getBeanInfo(B.class);
        PropertyDescriptor[] p = y.getPropertyDescriptors();
        for (int i = 0; i < p.length; i++) {
            if (p[i] instanceof IndexedPropertyDescriptor) {
                IndexedPropertyDescriptor ipe =(IndexedPropertyDescriptor)p[i];
                System.out.println("indexed prop: " +ipe.getName() + "<" + ipe.getIndexedPropertyType() + ">");
                System.out.println("\t" +ipe.getIndexedReadMethod() + "\n\t" +ipe.getIndexedWriteMethod());
                System.out.println("regular prop info also:");
            }
            System.out.println("prop: " + p[i].getName() +"<" + p[i].getPropertyType() + ">");
            System.out.println("\t" + p[i].getReadMethod() +"\n\t" +p[i].getWriteMethod());
        }
    }
    public static class A {
        public String getFoo(int x) {return null;}
    }
    public static class B extends A {
        public Date getFoo() {return null;}
    }
}

---------- End Source ----------

  Customer Workaround :
Work around (used in NetBeans' org.openide.nodes.BeanNode):
after getting PropertyDescriptor's from
Introspector.getBeanInfo, clean them up: if there are any
IndexedPropertyDescriptor's where getPropertyType() is not
null and yet not an array type, throw them out (ignore those
properties). Does not let the subclass property be used, but
at least prevents class cast exceptions and so on.
(Review ID: 137384)
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