How to get amount of serialized bytes representing a Java object?

Question

What syntax would I use to get the number of bytes representing a string and compare them to the number of bytes representing an ArrayList holding that string, for

Answer 1

I needed to check this accurately per-memcache write while investigating a server bug where memcache sizes were exceeded. To avoid the overhead of a big byte array for large objects I extended OutputStream as a counter:

public class CheckSerializedSize extends OutputStream {

    /** Serialize obj and count the bytes */
    public static long getSerializedSize(Serializable obj) {
        try {
            CheckSerializedSize counter = new CheckSerializedSize();
            ObjectOutputStream objectOutputStream = new ObjectOutputStream(counter);
            objectOutputStream.writeObject(obj);
            objectOutputStream.close();
            return counter.getNBytes();
        } catch (Exception e) {
            // Serialization failed
            return -1;
        }
    }

    private long nBytes = 0;

    private CheckSerializedSize() {}

    @Override
    public void write(int b) throws IOException {
        ++nBytes;
    }

    @Override
    public void write(byte[] b, int off, int len) throws IOException {
        nBytes += len;
    }

    public long getNBytes() {
        return nBytes;
    }
}