Also please follow coding guidelines when sending patches. (Braces)
john mcnally
Age Mooy wrote:
>
> Hi,
>
> I was trying to store query results in the global cache service using a key based on
>the hashcode of the
> Criteria object and I found out that hashcodes for equal Criteria are not equal.
>This breaks the rules because
> the Java spec says something like this:
>
> "If two objects are equal according to the equals(Object) method, then calling the
>hashCode method on each of
> the two objects must produce the same integer result"
>
> This problem occurs because the Criteria.Criterion inner class defines an equals()
>method without defining a
> matching hashCode() method.
>
> I played around a bit and came up with this implementation:
>
> /**
> * Returns a hash code value for the object.
> */
> public int hashCode()
> {
> int h = value.hashCode() + comparison.hashCode();
>
> if (table != null)
> h += table.hashCode();
>
> if (column != null)
> h += column.hashCode();
>
> if (and != null)
> h += and.hashCode();
>
> if (or != null)
> h += or.hashCode();
>
> return h;
> }
>
> I'm no hashCode expert but it works consistently with my tests.
>
> The patch for the above code (in jakarta-turbine-2) is attached below,
> Age
>
> Index: src/java/org/apache/turbine/util/db/Criteria.java
> ===================================================================
> RCS file:
>/home/cvspublic/jakarta-turbine-2/src/java/org/apache/turbine/util/db/Criteria.java,v
> retrieving revision 1.1.1.1
> diff -u -r1.1.1.1 Criteria.java
> --- src/java/org/apache/turbine/util/db/Criteria.java 2001/08/16 05:09:46
>1.1.1.1
> +++ src/java/org/apache/turbine/util/db/Criteria.java 2001/09/27 14:11:14
> @@ -3650,6 +3650,28 @@
> return isEquiv;
> }
>
> + /**
> + * Returns a hash code value for the object.
> + */
> + public int hashCode()
> + {
> + int h = value.hashCode() + comparison.hashCode();
> +
> + if (table != null)
> + h += table.hashCode();
> +
> + if (column != null)
> + h += column.hashCode();
> +
> + if (and != null)
> + h += and.hashCode();
> +
> + if (or != null)
> + h += or.hashCode();
> +
> + return h;
> + }
> +
> public String[] getAllTables()
> {
> StringStackBuffer tables = new StringStackBuffer();
>
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