StorageDisk Exception

[qing3gan]

I have a problem with StorageDisk.When i run the app in the first time, it will create files that is tomp2p and tomp2p.p on local filesystem, everything is ok, but when i run the app again, it reported a exception like below:

Caused by: java.lang.RuntimeException: Could not instantiate class
            at org.mapdb.SerializerPojo.deserializeUnknownHeader(SerializerPojo.java:483)
            at org.mapdb.SerializerBase.deserialize3(SerializerBase.java:1216)
            at org.mapdb.SerializerBase.deserialize(SerializerBase.java:1132)
            at org.mapdb.SerializerBase.deserialize(SerializerBase.java:867)
            at org.mapdb.SerializerPojo.deserialize(SerializerPojo.java:701)
            at org.mapdb.BTreeMap$NodeSerializer.deserialize(BTreeMap.java:449)
            at org.mapdb.BTreeMap$NodeSerializer.deserialize(BTreeMap.java:288)
            at org.mapdb.Store.deserialize(Store.java:297)
            at org.mapdb.StoreDirect.get2(StoreDirect.java:475)
            at org.mapdb.StoreDirect.get(StoreDirect.java:428)
            at org.mapdb.Caches$HashTable.get(Caches.java:245)
            at org.mapdb.EngineWrapper.get(EngineWrapper.java:58)
            at org.mapdb.BTreeMap.<init>(BTreeMap.java:541)
            at org.mapdb.BTreeMap.preinitCatalog(BTreeMap.java:178)
            at org.mapdb.DB.reinit(DB.java:88)
            at org.mapdb.DB.<init>(DB.java:83)
            at org.mapdb.DBMaker.make(DBMaker.java:668)
            at net.tomp2p.storage.StorageDisk.<init>(StorageDisk.java:85)
            at org.hive2hive.mobile.test.MapDBTestActivity.onCreate(MapDBTestActivity.java:39)

I just wanna do some work of restoring data, then i test the StorageDisk class(it almost a single opration of newing StorageDisk(...)),it's ok on pc but seems not work on android.

this is the source code:(it's very simple)

File path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
path.mkdir();
SignatureFactory signatureFactory = new RSASignatureFactory();
storageDisk = new StorageDisk(Number160.createHash("test1"), path, signatureFactory);

[ChronosXYZ]

I fully replaced old StorageDisk (on top of MapDB) by StorageBerkeleyDB (on top of BerkeleyDB), which works on Android and PC well. You can see my impl in https://github.com/ChronosX88/Influence-android