Why do we need serialVersionUID when extending RuntimeException?

Question

Why do we need serialVersionUID when extending RuntimeException? Is RuntimeException a serializable class?

public class DataNotFoundException extends RuntimeException {       
    /**
     * 
     */
    private static final long serialVersionUID = 1;

    public DataNotFoundException(String str)
    {
        super(str);
    }
}

Answer 1

RuntimeException extends Exception. Exception extends Throwable. Throwable implements Serializable. So DataNotFoundException is Serializable too

Answer 2

Yes, Throwables are Serializable. Serializable means that objects of that class can be converted into a sequence of bytes. Making an exception serializable means it can be transferred across the network between tiers of a distributed application.