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Thomas Neidhart resolved COLLECTIONS-576. ----------------------------------------- Resolution: Fixed Fix Version/s: 4.1 Fixed in r1705620. Thanks for the report and testcase. > MultiKey subclassing has deserialization problem since COLLECTIONS-266: > either declare protected readResolve() or MultiKey must be final > ---------------------------------------------------------------------------------------------------------------------------------------- > > Key: COLLECTIONS-576 > URL: https://issues.apache.org/jira/browse/COLLECTIONS-576 > Project: Commons Collections > Issue Type: Bug > Components: KeyValue > Affects Versions: 4.0 > Reporter: Stephan Roch > Fix For: 4.1 > > > MultiKey from collections 4 provides a transient hashCode and a *private* > readResolve to resolve COLLECTIONS-266: Issue with MultiKey when > serialized/deserialized via RMI. > Unfortunately the solution does not work in case of *subclassing*: > readResolve in MultiKey should be declared *protected* readResolve() to be > called during deserialization of the subclass. Otherwise MultiKey must be > final to avoid such subclassing. > *Testcase*: > {code:java|title=MultiKeySerializationTest.java} > package de.ivu.test.common.collections4; > import static org.junit.Assert.assertEquals; > import java.io.ByteArrayInputStream; > import java.io.ByteArrayOutputStream; > import java.io.IOException; > import java.io.ObjectInputStream; > import java.io.ObjectOutputStream; > import org.apache.commons.collections4.keyvalue.MultiKey; > import org.junit.Test; > public class MultiKeySerializationTest { > @Test > @SuppressWarnings("unchecked") > public void testReadResolveEqualHashCode() > throws IOException, ClassNotFoundException { > class MultiKey2<A, B> > extends MultiKey { > private static final long serialVersionUID = 1928896152249821416L; > public MultiKey2(A key1, B key2) { > super(key1, key2); > } > public A getFirst() { > return (A) getKey(0); > } > public B getSecond() { > return (B) getKey(1); > } > > // FIXME: MultiKey should either declare protected readResolve() > or must be final. > } > MultiKey2<String, String> one = new MultiKey2<>("bla", "blub"); > System.out.println(one.hashCode()); > ByteArrayOutputStream byteOut = new ByteArrayOutputStream(); > ObjectOutputStream out = new ObjectOutputStream(byteOut); > out.writeObject(one); > out.close(); > byte[] serialized = byteOut.toByteArray(); > ByteArrayInputStream byteIn = new ByteArrayInputStream(serialized); > ObjectInputStream in = new ObjectInputStream(byteIn); > MultiKey2<String, String> two = (MultiKey2<String, String>) > in.readObject(); > System.out.println(two.hashCode()); > assertEquals("hashCode must be equal - please check for protected > readResolve in MultiKey*", one.hashCode(), > two.hashCode()); > } > } > {code} > *Fix:* > {code:java|title=MultiKey.java} > @@ -274,7 +274,7 @@ > * only stable for the same process). > * @return the instance with recalculated hash code > */ > - private Object readResolve() { > + protected Object readResolve() { > calculateHashCode(keys); > return this; > } > {code} -- This message was sent by Atlassian JIRA (v6.3.4#6332)