### Question:
RFC2616Codec implements ICharArrayCodec { public static boolean isToken (@Nullable final String s) { if (s == null) return false; return isToken (s.toCharArray ()); } RFC2616Codec(); static boolean isToken(@Nullable final String s); static boolean isToken(@Nullable final char [] aChars); static boolean isMaybeEncoded(@Nullable final String s); static boolean isMaybeEncoded(@Nullable final char [] s); @Nonnegative @Override int getMaximumEncodedLength(@Nonnegative final int nDecodedLen); void encode(@Nullable final char [] aDecodedBuffer,
                      @Nonnegative final int nOfs,
                      @Nonnegative final int nLen,
                      @Nonnull @WillNotClose final Writer aWriter); @Nonnegative @Override int getMaximumDecodedLength(@Nonnegative final int nEncodedLen); void decode(@Nullable final char [] aEncodedBuffer,
                      @Nonnegative final int nOfs,
                      @Nonnegative final int nLen,
                      @Nonnull @WillNotClose final Writer aWriter);  }### Answer:
@Test public void testIsToken () { assertFalse (RFC2616Codec.isToken ("")); assertFalse (RFC2616Codec.isToken ((String) null)); assertFalse (RFC2616Codec.isToken ((char []) null)); assertFalse (RFC2616Codec.isToken ("abc ")); assertFalse (RFC2616Codec.isToken (" abc")); assertFalse (RFC2616Codec.isToken ("ab c")); assertFalse (RFC2616Codec.isToken ("ab[c")); assertFalse (RFC2616Codec.isToken ("(")); assertFalse (RFC2616Codec.isToken ("\\")); assertFalse (RFC2616Codec.isToken ("\"")); assertTrue (RFC2616Codec.isToken ("abc")); assertTrue (RFC2616Codec.isToken ("abc123")); assertTrue (RFC2616Codec.isToken ("123")); assertTrue (RFC2616Codec.isToken ("123abc")); }