Java Serializable Object to Byte Array

Question

Let\'s say I have a serializable class AppMessage.

I would like to transmit it as byte[] over sockets to another machine where it is rebuil

Answer 1

I also recommend to use SerializationUtils tool. I want to make a ajust on a wrong comment by @Abilash. The SerializationUtils.serialize() method is not restricted to 1024 bytes, contrary to another answer here.

public static byte[] serialize(Object object) {
    if (object == null) {
        return null;
    }
    ByteArrayOutputStream baos = new ByteArrayOutputStream(1024);
    try {
        ObjectOutputStream oos = new ObjectOutputStream(baos);
        oos.writeObject(object);
        oos.flush();
    }
    catch (IOException ex) {
        throw new IllegalArgumentException("Failed to serialize object of type: " + object.getClass(), ex);
    }
    return baos.toByteArray();
}

At first sight， you may think that new ByteArrayOutputStream(1024) will only allow a fixed size. But if you take a close look at the ByteArrayOutputStream, you will figure out the the stream will grow if necessary:

This class implements an output stream in which the data is written into a byte array. The buffer automatically grows as data is written to it. The data can be retrieved using toByteArray() and toString().