Filters the characters of a given CharSequence based on a provided IntPredicate and a specified Charset.

FilterCharacters.java

	/**
	 * Filters the characters of a given CharSequence based on a provided IntPredicate.
	 * This method is useful for removing unwanted characters from a string, such as non-alphanumeric characters.
	 *
	 * @param cs              The input CharSequence to be filtered.
	 * @param characterFilter The IntPredicate to determine which characters should be kept.
	 * @return A new String containing only the characters that satisfy the characterFilter.
	 */
	private String filterCharacters(final CharSequence cs, final IntPredicate characterFilter) {
		return cs
				.chars()
				.filter(characterFilter)
				.collect(StringBuilder::new, StringBuilder::appendCodePoint, StringBuilder::append)
				.toString();  // default Charset
	}

	/**
	 * Filters the characters of a given CharSequence based on a provided IntPredicate and a specified Charset.
	 * This method is useful for removing unwanted characters from a string, such as non-alphanumeric characters,
	 * while also ensuring the correct encoding is used with low over-head.
	 *
	 * @param cs              The input CharSequence to be filtered.
	 * @param charset         The Charset to be used for encoding the filtered characters.
	 * @param characterFilter The IntPredicate to determine which characters should be kept.
	 * @return A new String containing only the characters that satisfy the characterFilter, encoded using the specified
	 * charset.
	 */
	private String filterCharacters(final CharSequence cs, final Charset charset, final IntPredicate characterFilter) {
		final var sb = cs
				.chars()
				.filter(characterFilter)
				.collect(StringBuilder::new, StringBuilder::appendCodePoint, StringBuilder::append);

		// Required for specifying charset.
		final var byteBuffer = charset.encode(CharBuffer.wrap(sb));
		final var encodedBytes = new byte[byteBuffer.remaining()];
		byteBuffer.get(encodedBytes);
		return new String(encodedBytes);