Is this bug in java-provided utf-8 Charset ???

Question

Here is the little code I've done:
String serialisation = "myVeryComplexString ..."
String coding = new String(serialisation.getBytes("utf-8"));
String decoding = new String(coding.getBytes(), "utf-8");
I expected that "serialisation" and "decoding" are the same String. But they are not ...
The "serialisation.getBytes()" array contains 189 bytes. But the "decoding.getBytes()" array contains 191 bytes ... Why this difference ?
Any explaination ?

Answer 1

You aren't willing to listen. Maybe the soruce code for STring will convince you.
public final class String implements java.io.Serializable, Comparable {
    /** The value is used for character storage. */
    private char value[];
    /** The offset is the first index of the storage that is used. */
    private int offset;
    /** The count is the number of characters in the String. */
    private int count;
    /** Cache the hash code for the string */
    private int hash = 0;
    /** The cached converter for each thread.
     *  Note: These are declared null to minimize the classes
     *  that String must depend on during initialization
    private static ThreadLocal btcConverter = null;
    private static ThreadLocal ctbConverter = null;
     * Returns a <code>ByteToCharConverter</code> that uses the specified
     * encoding. For efficiency a cache is maintained that holds the last
     * used converter.
     * @param  enc The name of a character encoding
     * @return     ByteToCharConverter for the specified encoding.
     * @exception  UnsupportedEncodingException
     *             If the named encoding is not supported
     * @since      1.2
    private static ByteToCharConverter getBTCConverter(String encoding)
                                  throws UnsupportedEncodingException {
        ByteToCharConverter btc = null;
        if (btcConverter == null)
            btcConverter = new ThreadLocal();
        SoftReference ref = (SoftReference)(btcConverter.get());
        if (ref==null || (btc = (ByteToCharConverter)ref.get())==null ||
                          !encoding.equals(btc.getCharacterEncoding())) {
            btc = ByteToCharConverter.getConverter(encoding);
            btcConverter.set(new SoftReference(btc));
        } else {
            btc.reset();
        return btc;
...