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https://issues.apache.org/jira/browse/OPENJPA-1025?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Julien Kronegg updated OPENJPA-1025:
------------------------------------
Description:
AbstractResultList implements the basics for readonly result lists. When
calling the subList(int,int) method, the following exception is raised:
java.lang.UnsupportedOperationException
at
org.apache.openjpa.lib.rop.AbstractResultList.subList(AbstractResultList.java:84)
at
org.apache.openjpa.kernel.DelegatingResultList.subList(DelegatingResultList.java:308)
...
Since the subList() method contract is to create a new List from the
ResultList, this operation does not modify the original list: it only provides
a *view* on the original list (see
http://java.sun.com/docs/books/tutorial/collections/interfaces/list.html ).
This problem is also found by other users:
http://n2.nabble.com/DelegatingResultList.subList-not-implemented--td210389.html
They found the (bad) workaround to build a new List (bad because this is not
the same as calling subList()):
List mySubList = new ArrayList(openjpaList).subList(from, to);
The AbstractResultList class should be modified by one of this solution (sorted
by decreasing preference order):
1) the AbstractResultList class should extends java.util.AbstractList and the
subList() method should be removed (because implemented by AbstractList)
2) the subList() method should be implemented to return a view on the original
list. See java.util.AbstractList for an implementation
(http://www.koders.com/java/fidCFCB47A1819AB345234CC04B6A1EA7554C2C17C0.aspx?s=iso+3166
)
3) the subList() method should throw the exception with the message "this
method is not yet implemented. Workaround: new
ArrayList(openjpaList).subList(from, to)"
was:
AbstractResultList implements the basics for readonly result lists. When
calling the subList(int,int) method, the following exception is raised:
java.lang.UnsupportedOperationException
at
org.apache.openjpa.lib.rop.AbstractResultList.subList(AbstractResultList.java:84)
at
org.apache.openjpa.kernel.DelegatingResultList.subList(DelegatingResultList.java:308)
...
Since the subList() method contract is to create a new List from the
ResultList, this operation does not modify the original list.
Thus, the subList() method should not raise an exception but should return a
new list such as:
return new ArrayList(openjpaList).subList(from, to);
This problem is also found by other users:
http://n2.nabble.com/DelegatingResultList.subList-not-implemented--td210389.html
Remaining Estimate: 4h (was: 2h)
Original Estimate: 4h (was: 2h)
> AbstractResultList.subList throws UnsupportedOperationException
> ---------------------------------------------------------------
>
> Key: OPENJPA-1025
> URL: https://issues.apache.org/jira/browse/OPENJPA-1025
> Project: OpenJPA
> Issue Type: Bug
> Components: lib
> Affects Versions: 1.2.1, 1.3.0, 2.0.0
> Environment:
> http://svn.apache.org/viewvc/openjpa/trunk/openjpa-lib/src/main/java/org/apache/openjpa/lib/rop/AbstractResultList.java?revision=757278&view=markup,
> Seam 2.0, OpenJPA 1.2.1
> Reporter: Julien Kronegg
> Original Estimate: 4h
> Remaining Estimate: 4h
>
> AbstractResultList implements the basics for readonly result lists. When
> calling the subList(int,int) method, the following exception is raised:
> java.lang.UnsupportedOperationException
> at
> org.apache.openjpa.lib.rop.AbstractResultList.subList(AbstractResultList.java:84)
> at
> org.apache.openjpa.kernel.DelegatingResultList.subList(DelegatingResultList.java:308)
> ...
> Since the subList() method contract is to create a new List from the
> ResultList, this operation does not modify the original list: it only
> provides a *view* on the original list (see
> http://java.sun.com/docs/books/tutorial/collections/interfaces/list.html ).
> This problem is also found by other users:
> http://n2.nabble.com/DelegatingResultList.subList-not-implemented--td210389.html
> They found the (bad) workaround to build a new List (bad because this is not
> the same as calling subList()):
> List mySubList = new ArrayList(openjpaList).subList(from, to);
> The AbstractResultList class should be modified by one of this solution
> (sorted by decreasing preference order):
> 1) the AbstractResultList class should extends java.util.AbstractList and the
> subList() method should be removed (because implemented by AbstractList)
> 2) the subList() method should be implemented to return a view on the
> original list. See java.util.AbstractList for an implementation
> (http://www.koders.com/java/fidCFCB47A1819AB345234CC04B6A1EA7554C2C17C0.aspx?s=iso+3166
> )
> 3) the subList() method should throw the exception with the message "this
> method is not yet implemented. Workaround: new
> ArrayList(openjpaList).subList(from, to)"
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