src/share/classes/java/lang/Long.java

*** 264,281 ****
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       * @return  the string representation of the unsigned {@code long}
       *          value represented by the argument in hexadecimal
       *          (base 16).
       * @see #parseUnsignedLong(String, int)
       * @see #toUnsignedString(long, int)
+      * @see #toHexString(long, int)
       * @since   1.0.2
       */
      public static String toHexString(long i) {
          return toUnsignedString0(i, 4);
      }
  
      /**
       * Returns a string representation of the {@code long}
+      * argument as an unsigned integer in base 16, padded with
+      * leading zeroes if necessary.
+      *
+      * <p>The unsigned {@code long} value is the argument plus
+      * 2<sup>64</sup> if the argument is negative; otherwise, it is
+      * equal to the argument.  This value is converted to a string of
+      * ASCII digits in hexadecimal (base&nbsp;16) with possibly
+      * appended leading zeroes. A minimum amount of zeroes is appended
+      * to ensure the length of the resulting string is at least
+      * {@code minWidth}.
+      *
+      * <p>The value of the argument can be recovered from the returned
+      * string {@code s} by calling {@link
+      * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
+      * 16)}.
+      *
+      * <p>If the unsigned magnitude is zero, it is represented by a
+      * single zero character {@code '0'} ({@code '\u005Cu0030'}).
+      * The following characters are used as hexadecimal digits:
+      *
+      * <blockquote>
+      *  {@code 0123456789abcdef}
+      * </blockquote>
+      *
+      * These are the characters {@code '\u005Cu0030'} through
+      * {@code '\u005Cu0039'} and  {@code '\u005Cu0061'} through
+      * {@code '\u005Cu0066'}.  If uppercase letters are desired,
+      * the {@link java.lang.String#toUpperCase()} method may be called
+      * on the result:
+      *
+      * <blockquote>
+      *  {@code Long.toHexString(n, 12).toUpperCase()}
+      * </blockquote>
+      *
+      * @param   i   a {@code long} to be converted to a string.
+      * @param   minWidth a minimum required length of the resulting string.
+      * @return  the string representation of the unsigned {@code long}
+      *          value represented by the argument in hexadecimal
+      *          (base&nbsp;16), padded with leading zeroes if necessary.
+      * @see #parseUnsignedLong(String, int)
+      * @see #toUnsignedString(long, int)
+      * @see #toHexString(long)
+      * @since 1.9
+      */
+     public static String toHexString(long i, int minWidth) {
+         return toUnsignedString0(i, 4, minWidth);
+     }
+ 
+     /**
+      * Returns a string representation of the {@code long}
       * argument as an unsigned integer in base&nbsp;8.
       *
       * <p>The unsigned {@code long} value is the argument plus
       * 2<sup>64</sup> if the argument is negative; otherwise, it is
       * equal to the argument.  This value is converted to a string of
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          formatUnsignedLong(val, shift, buf, 0, chars);
          return new String(buf, true);
      }
  
      /**
+      * Format a long (treated as unsigned) into a String.
+      * @param val the value to format
+      * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
+      * @param minWidth the minimum width of the produced String
+      */
+     static String toUnsignedString0(long val, int shift, int minWidth) {
+         int mag = Long.SIZE - Long.numberOfLeadingZeros(val);
+         int magLen = (mag + (shift - 1)) / shift;
+         int zeroes = Math.max(Math.max(minWidth, 1) - magLen, 0);
+         char[] buf = new char[magLen + zeroes];
+ 
+         for (int i = 0; i < zeroes; ++i)
+             buf[i] = '0';
+         if (magLen > 0)
+             formatUnsignedLong(val, shift, buf, zeroes, magLen);
+         return new String(buf, true);
+     }
+ 
+     /**
       * Format a long (treated as unsigned) into a character buffer.
       * @param val the unsigned long to format
       * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
       * @param buf the character buffer to write to
       * @param offset the offset in the destination buffer to start at