serialversionuid is static and final but then why is it serializable

Question

As we know static fields are not serializable.

But the serialversionUID in our class is final and static. How is it serialized even if it is static and final?

Answer 1

During the serialization process, one of the things that gets written is the class descriptor. This class descriptor contains the name and the serialVersionUID of the class.

The method can be found in the class java.io.ObjectStreamClass(http://docs.oracle.com/javase/7/docs/api/java/io/ObjectStreamClass.html)

/**
 * Writes non-proxy class descriptor information to given output stream.
 */
void writeNonProxy(ObjectOutputStream out) throws IOException {
    out.writeUTF(name);
    out.writeLong(getSerialVersionUID());

    byte flags = 0;
    if (externalizable) {
        flags |= ObjectStreamConstants.SC_EXTERNALIZABLE;
        int protocol = out.getProtocolVersion();
        if (protocol != ObjectStreamConstants.PROTOCOL_VERSION_1) {
            flags |= ObjectStreamConstants.SC_BLOCK_DATA;
        }
    } else if (serializable) {
        flags |= ObjectStreamConstants.SC_SERIALIZABLE;
    }
    if (hasWriteObjectData) {
        flags |= ObjectStreamConstants.SC_WRITE_METHOD;
    }
    if (isEnum) {
        flags |= ObjectStreamConstants.SC_ENUM;
    }
    out.writeByte(flags);

    out.writeShort(fields.length);
    for (int i = 0; i < fields.length; i++) {
        ObjectStreamField f = fields[i];
        out.writeByte(f.getTypeCode());
         out.writeUTF(f.getName());
        if (!f.isPrimitive()) {
            out.writeTypeString(f.getTypeString());
        }
    }
}