How to solve InvalidClassException when reading an Object array in ObjectInputStream?

Question

I have to save and load a chess game. In Chess I have:

public class Chess 
{
private Piece[][] pieceArray;
private Board board;
private int moves;
private boolean turn;
...
Set's and get's
}

I would have to load the turn, moves and the matrix. For now Im only saving and loading the matrix (Pieces[][])

Now I have these methods for saving and loading the game in another class In this class I have a FTPClient connected to a server.

Saving the game:

public boolean saveGame(Chess chess) {
    boolean error = false;
    try {

        File file = new File("game.save");
        FileOutputStream fis = new FileOutputStream(file);
        ObjectOutputStream oos = new ObjectOutputStream(fis);
        oos.writeObject(chess.getArray());
        oos.close();

        // Save that file in the server
        FileInputStream fis = new FileInputStream(new File("game.save"));
        client.storeFile("game.save", fis);

        fis.close();
        file.delete();


    } catch (IOException e) {

        e.printStackTrace();
    }
    return error;

Saving the game gives me no problem and goes smoothly.

And now this is the method I use to load the game, which is the one throwing the invalidClassException.

try {
            FileInputStream fis = new FileInputStream(new File("game.save"));
            ObjectInputStream ois = new ObjectInputStream(fis);
            chess.setArray((Piece[][]) ois.readObject());
            chess.paintInBoard();
            ois.close();
        } catch (IOException | ClassNotFoundException e) {

            e.printStackTrace();
        }

Whenever I try to read the matriz I get "java.io.InvalidClassException: [LPiece;; invalid descriptor for field "

I have implemented the Serializable interface in Piece and Chess. I have tried saving the whole Chess class but doing that I would have to implement the Serializable interface in other 8 classes as well and I'm trying to avoid that. Do I have to read each Piece individually?

Thank you a lot.

Answer 1

I tried saving the saves locally and it worked. The problem was that the server I was using corrupted the file every time I uploaded it, giving me that exception. Changing the server did the job.