[BEANUTILS-277] BeanComparator - Unable to catch or handle NestedNullExceptions

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Won't Fix
• Affects Version/s: 1.7.0
• Component/s: Bean-Collections
• Assignee: Unassigned
• Reporter: Travis Greer
• Created: 04/May/07 16:50
• Updated: 25/Mar/08 08:08
• Resolved: 20/May/07 22:27

Description

I believe there's a bug in org.apache.commons.beanutils.BeanComparator.

When sorting on a nested property, a org.apache.commons.beanutils.NestedNullException is thrown if a null property is encountered.

For example, say I have a list of Actors and want to sort on "spouse.name". If any one of the actors does not have a spouse (spouse == null), the sort will fail, throwing a NestedNullException and wrapping that in a ClassCastException.

Adding a NullComparator to the BeanComparator does not fix the problem because the null won't be detected until PropertyUtils.getProperty attempts to get the property - at which point it's too late.

There's probably a better way to fix this, but replacing the compare method with this seems to work for me (in addition to adding a NullComparator to BeanComparator):

public int compare( Object o1, Object o2 ) {

if ( property == null )

{ // compare the actual objects return comparator.compare( o1, o2 ); }

try {
Object value1 = null;
Object value2 = null;
try

{ value1 = PropertyUtils.getProperty( o1, property ); }

catch (NestedNullException nne) {}
try

{ value2 = PropertyUtils.getProperty( o2, property ); }

catch (NestedNullException nne) {}
return comparator.compare(value1, value2);
}
catch ( Exception e )

{ throw new ClassCastException( e.toString() ); }

}

I apologize if this is the incorrect way to go about this - I'm new at this.