Question

This is my first attempt at serializing/deserializing objects on any platform and, to put it mildly, I’m confused.

After implementing Serializable to my game object I output it to a file thus:

public void saveGameState(){


    ByteArrayOutputStream bos = new ByteArrayOutputStream(); 

    try { 


        ObjectOutput out = new ObjectOutputStream(bos); 
          out.writeObject(theGame);//theGame is an instance of the custom class                  
                                          //TGame which stores game info.

          byte[] buf = bos.toByteArray(); 

          FileOutputStream fos = this.openFileOutput(filename,                      
                   Context.MODE_PRIVATE);
          fos.write(buf);
          fos.close(); 
        } catch(IOException ioe) { 
          Log.e("serializeObject", "error", ioe); 


        } 
        File f =this.getDir(filename, 0);
        Log.v("FILE",f.getName());    
}

This seems to work, in that I get no exceptions raised. I can only know for sure when I deserialize it. Which is where things go pear shaped.

public God loadSavedGame(){
    TGame g=null;
    InputStream instream = null;
    try {
        instream = openFileInput(filename);
    } catch (FileNotFoundException e) {

        e.printStackTrace();
        return null;
    }
     try {
        ObjectInputStream ois = new ObjectInputStream(instream);

         try {
            g= (TGame) ois.readObject();
            return g;
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            return null;
        }
     } catch (StreamCorruptedException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        return null;
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        return null;
    }
          }

I got the basis of this code from here Android Java — Deserializing a file on the Android platform and tried to modify it for my app. When running I get

 05-31 23:30:45.493: ERROR/copybit(1279): copyBits failed (Invalid argument)

When the output should be loaded and the saved game start up from when it was saved.
Any help would be appreciated.

Answer 1

The error you’ve shown is not at all related to serialization: its actually a video display error. I’d suggest looking at the object BEFORE you serialize to make sure its not null, and I’d also suggest serializing to a file on the SD card to make sure you actually had data output (so use new FileOutputStream("/mnt/sdcard/serializationtest") as the output stream and new FileInputStream("/mnt/sdcard/serializationtest") as the input stream) while you are debugging; you can switch back to the context methods after it works, but make sure your sdcard is plugged in while you are doing this.

Finally, modify your logging to look like this:

try {
        ObjectInputStream ois = new ObjectInputStream(instream);

         try {
            g= (TGame) ois.readObject();
            return g;
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            android.util.Log.e("DESERIALIZATION FAILED (CLASS NOT FOUND):"+e.getMessage(), e);
            e.printStackTrace();
            return null;
        }
     } catch (StreamCorruptedException e) {
            android.util.Log.e("DESERIALIZATION FAILED (CORRUPT):"+e.getMessage(), e);
        // TODO Auto-generated catch block
        e.printStackTrace();
        return null;
    } catch (IOException e) {
            android.util.Log.e("DESERIALIZATION FAILED (IO EXCEPTION):"+e.getMessage(), e);
        // TODO Auto-generated catch block
        e.printStackTrace();
        return null;
    }

and see what error gets returned. I expect the serialization is failing somehow.