src/share/classes/java/lang/Integer.java

rev 7120 : 8007398: Peformance improvements to Integer and Long string formatting.
Reviewed-by: mdugiou, martin, darcy
Contributed-by: Steven Schlansker <stevenschlansker@gmail.com>, Mike Duigou <mike.duigou@oracle.com>

*** 24,34 ****
   */
  
  package java.lang;
  
  import java.lang.annotation.Native;
- import java.util.Properties;
  
  /**
   * The {@code Integer} class wraps a value of the primitive type
   * {@code int} in an object. An object of type {@code Integer}
   * contains a single field whose type is {@code int}.
--- 24,33 ----
*** 183,193 ****
       * @return  an unsigned string representation of the argument in the specified radix.
       * @see     #toString(int, int)
       * @since 1.8
       */
      public static String toUnsignedString(int i, int radix) {
!         return Long.toString(toUnsignedLong(i), radix);
      }
  
      /**
       * Returns a string representation of the integer argument as an
       * unsigned integer in base 16.
--- 182,192 ----
       * @return  an unsigned string representation of the argument in the specified radix.
       * @see     #toString(int, int)
       * @since 1.8
       */
      public static String toUnsignedString(int i, int radix) {
!         return Long.toUnsignedString(toUnsignedLong(i), radix);
      }
  
      /**
       * Returns a string representation of the integer argument as an
       * unsigned integer in base 16.
*** 305,328 ****
      }
  
      /**
       * Convert the integer to an unsigned number.
       */
!     private static String toUnsignedString0(int i, int shift) {
!         char[] buf = new char[32];
!         int charPos = 32;
          int radix = 1 << shift;
          int mask = radix - 1;
          do {
!             buf[--charPos] = digits[i & mask];
!             i >>>= shift;
!         } while (i != 0);
  
!         return new String(buf, charPos, (32 - charPos));
      }
  
- 
      final static char [] DigitTens = {
          '0', '0', '0', '0', '0', '0', '0', '0', '0', '0',
          '1', '1', '1', '1', '1', '1', '1', '1', '1', '1',
          '2', '2', '2', '2', '2', '2', '2', '2', '2', '2',
          '3', '3', '3', '3', '3', '3', '3', '3', '3', '3',
--- 304,346 ----
      }
  
      /**
       * Convert the integer to an unsigned number.
       */
!     private static String toUnsignedString0(int val, int shift) {
!         // assert shift > 0 && shift <=5 : "Illegal shift value";
!         int mag = Integer.SIZE - Integer.numberOfLeadingZeros(val);
!         int chars = Math.max(((mag + (shift - 1)) / shift), 1);
!         char[] buf = new char[chars];
! 
!         formatUnsignedInt(val, shift, buf, 0, chars);
! 
!         // Use special constructor which takes over "buf".
!         return new String(buf, true);
!     }
! 
!     /**
!      * Format a long (treated as unsigned) into a character buffer.
!      * @param val the unsigned int 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
!      * @param len the number of characters to write
!      * @return the lowest character  location used
!      */
!      static int formatUnsignedInt(int val, int shift, char[] buf, int offset, int len) {
!         int charPos = len;
          int radix = 1 << shift;
          int mask = radix - 1;
          do {
!             buf[offset + --charPos] = Integer.digits[val & mask];
!             val >>>= shift;
!         } while (val != 0 && charPos > 0);
  
!         return charPos;
      }
  
      final static char [] DigitTens = {
          '0', '0', '0', '0', '0', '0', '0', '0', '0', '0',
          '1', '1', '1', '1', '1', '1', '1', '1', '1', '1',
          '2', '2', '2', '2', '2', '2', '2', '2', '2', '2',
          '3', '3', '3', '3', '3', '3', '3', '3', '3', '3',
*** 873,882 ****
--- 891,901 ----
  
      /**
       * Returns the value of this {@code Integer} as a {@code long}
       * after a widening primitive conversion.
       * @jls 5.1.2 Widening Primitive Conversions
+      * @see Integer#toUnsignedLong(int)
       */
      public long longValue() {
          return (long)value;
      }