Why isn't Java's nio.ByteBuffer serializable?

Question

Sometimes it would make sense to serialize it across with rest of data. Right now we have to unwrap it.

Edit: is there some other option available? E.g. Apache commons lang has MutableInt which is lightweight wrapper around primitive int?

Answer 1

I answered in the next post with an example for custom serialization: How to serialize ByteBuffer

Basically the point is that ByteBuffer is a wrapper for byte arrays so it has no sense to serialize it (instead you should serialize the byte[]). Just in case you need to serialize a ByteBuffer then... do something like

public class NetByteBuffer implements java.io.Serializable {
    private static final long serialVersionUID = -2831273345165209113L;

    //serializable property
    String anotherProperty;

    // mark as transient so this is not serialized by default
    transient ByteBuffer data;

    public NetByteBuffer(String anotherProperty, ByteBuffer data) {
        this.data = data;
        this.anotherProperty = anotherProperty;
    }

    public ByteBuffer getData() {
        return this.data;
    }

    private void writeObject(ObjectOutputStream out) throws IOException {
        // write default properties
        out.defaultWriteObject();
        // write buffer capacity and data
        out.writeInt(data.capacity());
        out.write(data.array());

    }

    private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
        //read default properties
        in.defaultReadObject();

        //read buffer data and wrap with ByteBuffer
        int bufferSize = in.readInt();
        byte[] buffer = new byte[bufferSize];
        in.read(buffer, 0, bufferSize);
        this.data = ByteBuffer.wrap(buffer, 0, bufferSize);
    }

    public String getAnotherProperty() {
        return anotherProperty;
    }

}