checkTryParse(Double.POSITIVE_INFINITY, "Infinity");
    checkTryParse(Double.POSITIVE_INFINITY, "+Infinity");
    checkTryParse(Double.NEGATIVE_INFINITY, "-Infinity");
  }

  private static final String[] BAD_TRY_PARSE_INPUTS = {
    "",
    "+-",
    "+-0",
    " 5",
    "32 ",
    " 55 ",
    "infinity",
    "POSITIVE_INFINITY",
    "0x9A",
    "0x9A.bE-5",
    ".",

    String hex = "(?:[0-9a-fA-F]+#(?:\\.[0-9a-fA-F]*#)?|\\.[0-9a-fA-F]+#)";
    String completeHex = "0[xX]" + hex + "[pP][+-]?\\d+#[fFdD]?";
    String fpPattern = "[+-]?(?:NaN|Infinity|" + completeDec + "|" + completeHex + ")";
    fpPattern =
        fpPattern.replace(
            "#",
            "+"
            );
    return
    java.util.regex.Pattern
        .compile(fpPattern);

  // algorithm would lead to an overflow.

  static boolean fitsInInt(long x) {
    return (int) x == x;
  }

  /**
   * Returns the arithmetic mean of {@code x} and {@code y}, rounded toward negative infinity. This
   * method is resilient to overflow.
   *
   * @since 14.0
   */
  public static long mean(long x, long y) {
    // Efficient method for computing the arithmetic mean.