collection.contains() returning false

pitosalas · **Joined:** Tue Sep 30, 2003 4:16 pm **Posts:** 33

I am using Hibernete 2.1, with HSQLDB 1.7.1.

This is a further simplification of a previous post which is still causing me problems. Essentially a call to collections.contains(x) is returning false where it should be returning true.

I checked my code carefully and both hashCode() and equals() are correct.

Here is the code:

Code:

// ensure that 'group' is updated 
ChannelGroup group is set to a valid ChannelGroup...

session = sessions.openSession() 
transaction = session.beginTransaction(); 
session.update(group); 

// get first channel in collection 
Collection channels = group.getChannelGroup().getChannels(); 
Iterator iter = channels.iterator(); 
channel = (Channel) iter.next(); 

// Close transaction
transaction.commit(); 
session.flush(); 
session.close(); 
session = null; 
transaction = null; 

// Start a new one (needed?)
session = sessions.openSession() 
transaction = session.beginTransaction(); 

// *** PROBLEM OCCURS HERE
assert (group.channels.contains(channel)) // fails!

transaction.commit(); 
session.flush(); 
session.close();

Note that that channels is a Set.

If I single step through this, I note the following:

- I can verify that the hashCode for channel equals the hashCode for the first non-null element of channels.
- the channels.contains() call is actually implemented by net.sf.hibernate.collection.Set
- Which in turn calls java.util.HashSet.contains()
- Which in turn calls java.util.HashMap.contains()
- Which FAILS to find the identical entry.

(By the way while I am positive about the fact that HashSet and HashMap methods are being called, due to the absence of debug info I am not 100% sure those are the specific methods.)

Can you tell what's wrong?

Thanks!

Here is the mapping for ChannelGroup

Code:

<?xml version="1.0"?> 

<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 2.0//EN" 
    "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd"> 

<hibernate-mapping> 
    <class 
        name="de.nava.informa.impl.hibernate.ChannelGroup" 
        table="CHANNEL_GROUPS" 
        dynamic-update="false" 
        dynamic-insert="false" 
    > 

        <id 
            name="intId" 
            column="CHANNEL_GROUP_ID" 
            type="integer" 
        > 
            <generator class="native"> 
            </generator> 
        </id> 

        <property 
            name="title" 
            type="java.lang.String" 
            update="true" 
            insert="true" 
            column="TITLE" 
            not-null="true" 
        /> 

        <set 
            name="channels" 
            table="CAT_GROUP_CHANNEL" 
            lazy="true" 
            inverse="false" 
            cascade="none" 
            sort="unsorted" 
        > 

              <key 
                  column="GROUP_ID" 
              /> 

              <many-to-many 
                  class="de.nava.informa.impl.hibernate.Channel" 
                  column="CHANNEL_ID" 
                  outer-join="auto" 
              /> 

        </set> 

        <many-to-one 
            name="parent" 
            class="de.nava.informa.impl.hibernate.ChannelGroup" 
            cascade="none" 
            outer-join="auto" 
            update="true" 
            insert="true" 
            column="PARENT_ID" 
        /> 

        <bag 
            name="children" 
            lazy="true" 
            inverse="false" 
            cascade="none" 
            order-by="CHANNEL_GROUP_ID" 
        > 

              <key 
                  column="PARENT_ID" 
              /> 

              <one-to-many 
                  class="de.nava.informa.impl.hibernate.ChannelGroup" 
              /> 
        </bag> 

        <!-- 
            To add non XDoclet property mappings, create a file named 
                hibernate-properties-ChannelGroup.xml 
            containing the additional properties and place it in your merge dir. 
        --> 

    </class> 

</hibernate-mapping> 

And here is the mapping for 'Channel':

Code:

<?xml version="1.0"?> 

<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 2.0//EN" 
    "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd"> 

<hibernate-mapping> 
    <class 
        name="de.nava.informa.impl.hibernate.Channel" 
        table="CHANNELS" 
        dynamic-update="false" 
        dynamic-insert="false" 
    > 

        <id 
            name="intId" 
            column="CHANNEL_ID" 
            type="integer" 
        > 
            <generator class="native"> 
            </generator> 
        </id> 

        <property 
            name="title" 
            type="java.lang.String" 
            update="true" 
            insert="true" 
            column="TITLE" 
            not-null="true" 
        /> 

        <property 
            name="description" 
            type="java.lang.String" 
            update="true" 
            insert="true" 
            column="DESCRIPTION" 
        /> 

        <property 
            name="locationString" 
            type="string" 
            update="true" 
            insert="true" 
            column="LOCSTRING" 
        /> 

        <property 
            name="site" 
            type="java.net.URL" 
            update="true" 
            insert="true" 
            column="SITE" 
        /> 

        <property 
            name="creator" 
            type="java.lang.String" 
            update="true" 
            insert="true" 
            column="CREATOR" 
        /> 

        <property 
            name="publisher" 
            type="java.lang.String" 
            update="true" 
            insert="true" 
            column="PUBLISHER" 
        /> 

        <property 
            name="language" 
            type="java.lang.String" 
            update="true" 
            insert="true" 
            column="LANGUAGE" 
        /> 

        <property 
            name="formatString" 
            type="string" 
            update="true" 
            insert="true" 
            column="FORMAT" 
        /> 

        <bag 
            name="items" 
            table="ITEMS" 
            lazy="false" 
            inverse="false" 
            cascade="all" 
        > 

              <key 
                  column="CHANNEL_ID" 
              /> 

              <one-to-many 
                  class="de.nava.informa.impl.hibernate.Item" 
              /> 
        </bag> 

        <many-to-one 
            name="image" 
            class="de.nava.informa.impl.hibernate.Image" 
            cascade="none" 
            outer-join="auto" 
            update="true" 
            insert="true" 
            column="IMAGE_ID" 
            not-null="false" 
        /> 

        <many-to-one 
            name="textInput" 
            class="de.nava.informa.impl.hibernate.TextInput" 
            cascade="none" 
            outer-join="auto" 
            update="true" 
            insert="true" 
            column="TEXTINPUT_ID" 
            not-null="false" 
        /> 

        <property 
            name="copyright" 
            type="java.lang.String" 
            update="true" 
            insert="true" 
            column="COPYRIGHT" 
        /> 

        <property 
            name="rating" 
            type="java.lang.String" 
            update="true" 
            insert="true" 
            column="RATING" 
        /> 

        <many-to-one 
            name="cloud" 
            class="de.nava.informa.impl.hibernate.Cloud" 
            cascade="none" 
            outer-join="auto" 
            update="true" 
            insert="true" 
            column="CLOUD_ID" 
            not-null="false" 
        /> 

        <property 
            name="generator" 
            type="java.lang.String" 
            update="true" 
            insert="true" 
            column="GENERATOR" 
        /> 

        <property 
            name="docs" 
            type="java.lang.String" 
            update="true" 
            insert="true" 
            column="DOCS" 
        /> 

        <property 
            name="ttl" 
            type="int" 
            update="true" 
            insert="true" 
            column="TTL" 
        /> 

        <bag 
            name="categories" 
            table="CAT_CHANNEL_LINK" 
            lazy="true" 
            inverse="false" 
            cascade="none" 
        > 

              <key 
                  column="CHANNEL_ID" 
              /> 

              <many-to-many 
                  class="de.nava.informa.impl.hibernate.Category" 
                  column="CATEGORY_ID" 
                  outer-join="auto" 
              /> 

        </bag> 

        <property 
            name="lastUpdated" 
            type="java.util.Date" 
            update="true" 
            insert="true" 
            column="LAST_UPDATED" 
        /> 

        <property 
            name="lastBuildDate" 
            type="java.util.Date" 
            update="true" 
            insert="true" 
            column="LAST_BUILD_DATE" 
        /> 

        <property 
            name="pubDate" 
            type="java.util.Date" 
            update="true" 
            insert="true" 
            column="PUB_DATE" 
        /> 

        <property 
            name="updatePeriod" 
            type="java.lang.String" 
            update="true" 
            insert="true" 
            column="UPDATE_PERIOD" 
        /> 

        <property 
            name="updateFrequency" 
            type="int" 
            update="true" 
            insert="true" 
            column="UPDATE_FREQUENCY" 
        /> 

        <property 
            name="updateBase" 
            type="java.util.Date" 
            update="true" 
            insert="true" 
            column="UPDATE_BASE" 
        /> 

        <!-- 
            To add non XDoclet property mappings, create a file named 
                hibernate-properties-Channel.xml 
            containing the additional properties and place it in your merge dir. 
        --> 

    </class> 

</hibernate-mapping> 

mnuhoglu · **Posted:** Wed Jun 23, 2004 8:05 am

I have a similar problem. contains() method doesn't work as expected.

Code:

        // office is a persistent object
        Set cars = office.getCars().keySet();
        Predicate findBmw = new Predicate(){
            public boolean evaluate(Object o) {
                return o.equals( bmw );
            }
        };
        assertEquals( bmw , CollectionUtils.find( cars , bmw ) ); // passes
        assertTrue( cars.contains( bmw ) ); // fails

In this code, the second assertion fails. Although, the first and second assertions do exactly the same thing. They check if the specified object is in the 'cars' set.

So it makes me think, that contains() has a different semantics than equals().

What do you think?

Thanks...

jlawmi · **Joined:** Mon Nov 24, 2003 6:36 pm **Posts:** 105

I've used both of these types of patterns in my code without fail. I think it is likely your equals is broken. Can you show them to us?

mnuhoglu · **Posted:** Thu Jun 24, 2004 2:00 am

Here is the equals method:

Code:

    public boolean equals(Object o) {
        if (this == o) return true;
        if (!(o instanceof Entity)) return false;

        final Entity entity = (Entity) o;

        if ( id == null ) return ( this == o ) ;

        if (id != null ? !id.equals(entity.id) : entity.id != null) return false;

        return true;
    }

All the persistent classes inherit from Entity class, which defines id and eq/hc.

Thanks...