Hi, thank you for your information.
I slightly modified my second test case and run it on JDK6-beta.
public void test_HeadMap_Serializable() throws Exception {
// same as before
*assertNotNull(((SortedMap)outputObject).entrySet()); // This line
assertNull previously.*
assertNotNull(((SortedMap)outputObject).keySet());
assertNotNull(((SortedMap)outputObject).values());
*assertEquals(outputObject, headMap); // This line is previously
commented out, and now passes on JDK6.*
}
IMO, this shows that Inner classes of TreeMap on JDK5 do not have proper
serialization behavior. Shall we follow RI on this odd behavior in harmony?
Personally, I am against this.
Best regards
Oleg Khaschansky 写道:
Hi,
Take a look at this:
http://download.java.net/jdk6/docs/api/serialized-form.html
Maybe this document will give you an idea of what are those inner
classes... Of cause, in the new release serialized form may have
changed.
--
Oleg
On 8/7/06, Spark Shen <[EMAIL PROTECTED]> wrote:
Hi:
This is a long post, thanks for your patient to read it through :-)
I wrote a test case as below:
public void test_SubMap_Serializable() throws Exception {
TreeMap<Integer, Double> map = new TreeMap<Integer, Double>();
map.put(1, 2.1);
map.put(2, 3.1);
map.put(3, 4.5);
map.put(7, 21.3);
SortedMap<Integer, Double> headMap = map.headMap(3);
assertTrue(headMap instanceof Serializable);
assertFalse(headMap instanceof TreeMap);
assertTrue(headMap instanceof SortedMap);
}
Which says the returned headMap is not a TreeMap but a serializable
SortedMap.
IIRC, there are three mysterious serialized form immediately following
the serialized form of java.util.TreeMap. They are
Class **java.util.TreeMap$1** extends Object implements Serializable
Class **java.util.TreeMap$2** extends Object implements Serializable
Class **java.util.TreeMap$3** extends Object implements Serializable
respectively. This gives a hint that there are three inner classes of
TreeMap which should be serializable.
But what are they indeed?
IMHO, the returned SortedMap may
be one of the java.util.TreeMap$x classes. What is your opinion? (I
raised JIRA-1066 for this)
The above test case suggests me to make the returned SortedMap
serializable. But, I have another concern:
SortedMap returned by TreeMap is not a public class(does not have a
documented Serialized form), and the serialization behavior of this
SortedMap is strange. See the test case below:
public void test_HeadMap_Serializable() throws Exception {
TreeMap<Integer, Double> map = new TreeMap<Integer, Double>();
map.put(1, 2.1);
map.put(2, 3.1);
map.put(3, 4.5);
map.put(7, 21.3);
SortedMap<Integer, Double> headMap = map.headMap(3);
assertTrue(headMap instanceof Serializable);
assertFalse(headMap instanceof TreeMap);
assertTrue(headMap instanceof SortedMap);
// Write the SortedMap out and read it back.
ByteArrayOutputStream bos = new ByteArrayOutputStream();
ObjectOutputStream oos = new ObjectOutputStream(bos);
oos.writeObject(headMap);
oos.close();
ByteArrayInputStream bis = new
ByteArrayInputStream(bos.toByteArray());
ObjectInputStream ois = new ObjectInputStream(bis);
Object outputObject = (Object) ois.readObject();
*assertNull(((SortedMap)outputObject).entrySet());
assertNotNull(((SortedMap)outputObject).keySet());
assertNotNull(((SortedMap)outputObject).values());
* *// assertEquals(outputObject, headMap);*
}
The commented out assertion will throw out a NullPointerException, and
the entrySet of the SortedMap is Null while keySet and values are not.
This is strange. Do we need to follow RI to make the returned SortedMap
serializable like this?
Best regards
--
Spark Shen
China Software Development Lab, IBM
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China Software Development Lab, IBM
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