How to open bitcoin-qt wallet with bitcoinj

Question

I am trying to open my bitcoin-qt wallet with bitcoinj. I have this simple code:

private static final File WALLET_FILE = new File("__PATH__");


public static void main(String[] args) {

    Wallet wallet;

    try {

        wallet = Wallet.loadFromFile(WALLET_FILE);

    } catch (IOException e) {

    System.out.println("Couldn't open wallet: " + e);

    return;

    }


    System.out.println("Balance: " + wallet.getBalance());

}

I get an error:

Couldn't open wallet: com.google.protobuf.InvalidProtocolBufferException: Protocol message contained an invalid tag (zero).

How to solve this?