Mapped deserialization attribute mixup

Question

I use the following class to deserialize a string and map the incoming classes to new ones in a different package.

They contain the exact same attributes ( except the mapped equivalents ) and the same serial version uid.

public class CompatibilityImporter {


public void loadOldImport(final File f, final CompatibilityImportListener importListener, final String password) {
    new Thread(new Runnable() {
        @Override
        public void run() {
            try {
                String oldExport = readFileAsString(f);
                ObjectInputStream ois = new ClassNameMappingObjectInputStream(new ByteArrayInputStream(Base64.decode(oldExport, Base64.DEFAULT)));
                ExportPackageCompat exportPackage = (ExportPackageCompat) ois.readObject();
                importListener.onImportDone();
            } catch (Exception e) {
                Log.e(e, "Compatibility Import failed! ");
                importListener.onImportError();
            }
        }
    }).start();
}

public class ClassNameMappingObjectInputStream extends ObjectInputStream {

    public Map<String, Class> classNameMapping = initclassNameMapping();

    public ClassNameMappingObjectInputStream(InputStream in) throws IOException {
        super(in);
        initclassNameMapping();
    }

    protected ClassNameMappingObjectInputStream() throws IOException, SecurityException {
        super();
        initclassNameMapping();
    }

    private Map<String, Class> initclassNameMapping() {
        Map<String, Class> res = new HashMap<String, Class>();
        res.put("com.example.myapp.app.settings.backup.ExportPackage", ExportPackageCompat.class);
        res.put("com.example.myapp.app.settings.backup.ExportPackage$SavedPhotoFile", SavedPhotoFileCompat.class);
        // all the other model mappings
        return Collections.unmodifiableMap(res);
    }

    @Override
    protected java.io.ObjectStreamClass readClassDescriptor()
            throws IOException, ClassNotFoundException {
        ObjectStreamClass desc = super.readClassDescriptor();
        Log.d("ObjectInputStream", "Reading descriptor -> " + desc);
        if (classNameMapping.containsKey(desc.getName())) {
            return ObjectStreamClass.lookup(classNameMapping.get(desc.getName()));
        }
        return desc;
    }
}
}

For some reason at some point the desiarialisation process seems to try to match 2 attributes that cant go together.

(A String attribute phone is tryed to be written with an arraylist. )

Here is the Logcat:

22953-23138/com.example.myapp D/ObjectInputStream﹕ Reading descriptor -> 
com.example.myapp.app.settings.backup.ExportPackage: static final long serialVersionUID =3985293256L;
22953-23138/com.example.myapp D/ObjectInputStream﹕ Reading descriptor -> java.util.ArrayList: static final long serialVersionUID =8683452581122892189L;
22953-23138/com.example.myapp D/ObjectInputStream﹕ Reading descriptor -> com.example.myapp.model.Crate: static final long serialVersionUID =-2892184805959193218L;
22953-23138/com.example.myapp D/ObjectInputStream﹕ Reading descriptor -> java.util.Date: static final long serialVersionUID =7523967970034938905L;
22953-23138/com.example.myapp D/ObjectInputStream﹕ Reading descriptor -> com.example.myapp.model.Shipment: static final long serialVersionUID =-2477342699440006438L;
22953-23138/com.example.myapp D/ObjectInputStream﹕ Reading descriptor -> com.example.myapp.model.Photo: static final long serialVersionUID =-3384005512499715344L;
22953-23138/com.example.myapp D/ObjectInputStream﹕ Reading descriptor -> com.example.myapp.app.settings.backup.ExportPackage$Extras: static final long serialVersionUID =4664556672506779299L;
22953-23138/com.example.myapp D/ObjectInputStream﹕ Reading descriptor -> [B: static final long serialVersionUID =-5984413125824719648L;
22953-23138/com.example.myapp D/ObjectInputStream﹕ Reading descriptor -> com.example.myapp.model.Shipment$ShipmentType: static final long serialVersionUID =0L;
22953-23138/com.example.myapp D/ObjectInputStream﹕ Reading descriptor -> java.lang.Enum: static final long serialVersionUID =0L;
22953-23138/com.example.myapp D/ObjectInputStream﹕ Reading descriptor -> com.example.myapp.model.Donut: static final long serialVersionUID =-5666180507659888627L;
22953-23138/com.example.myapp D/ObjectInputStream﹕ Reading descriptor -> com.example.myapp.model.DonutPackage: static final long serialVersionUID =5365476511704148082L;
22953-23138/com.example.myapp E/Apotheke﹕ Compatibility Import failed!
    java.lang.ClassCastException: com.example.myapp.app.settings.backup.compatibility.CrateCompat.phone - class java.lang.String not compatible with class java.util.ArrayList
            at java.io.ObjectInputStream.readFieldValues(ObjectInputStream.java:1151)
            at java.io.ObjectInputStream.defaultReadObject(ObjectInputStream.java:455)
            at java.io.ObjectInputStream.readObjectForClass(ObjectInputStream.java:1372)
            at java.io.ObjectInputStream.readHierarchy(ObjectInputStream.java:1269)
            at java.io.ObjectInputStream.readNewObject(ObjectInputStream.java:1858)
            at java.io.ObjectInputStream.readNonPrimitiveContent(ObjectInputStream.java:787)
            at java.io.ObjectInputStream.readObject(ObjectInputStream.java:2006)
            at java.io.ObjectInputStream.readObject(ObjectInputStream.java:1963)
            at java.util.ArrayList.readObject(ArrayList.java:661)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:525)
            at java.io.ObjectInputStream.readObjectForClass(ObjectInputStream.java:1357)
            at java.io.ObjectInputStream.readHierarchy(ObjectInputStream.java:1269)
            at java.io.ObjectInputStream.readNewObject(ObjectInputStream.java:1858)
            at java.io.ObjectInputStream.readNonPrimitiveContent(ObjectInputStream.java:787)
            at java.io.ObjectInputStream.readObject(ObjectInputStream.java:2006)
            at java.io.ObjectInputStream.readObject(ObjectInputStream.java:1963)
            at java.io.ObjectInputStream.readFieldValues(ObjectInputStream.java:1140)
            at java.io.ObjectInputStream.defaultReadObject(ObjectInputStream.java:455)
            at java.io.ObjectInputStream.readObjectForClass(ObjectInputStream.java:1372)
            at java.io.ObjectInputStream.readHierarchy(ObjectInputStream.java:1269)
            at java.io.ObjectInputStream.readNewObject(ObjectInputStream.java:1858)
            at java.io.ObjectInputStream.readNonPrimitiveContent(ObjectInputStream.java:787)
            at java.io.ObjectInputStream.readObject(ObjectInputStream.java:2006)
            at java.io.ObjectInputStream.readObject(ObjectInputStream.java:1963)
            at com.example.myapp.app.settings.backup.compatibility.CompatibilityImporter$1.run(CompatibilityImporter.java:48)
            at java.lang.Thread.run(Thread.java:841)

Has anyone any idea what might go wrong?

I'm hoping for someone who shared and solved my problem or knows how the mixup between the attributes might happen.

Answer 1

In one of the Objects i mapped to an attribute was missing and caused the mixup.

My mistake!