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

@@ -225,18 +225,69 @@
      * @param   i   an integer to be converted to a string.
      * @return  the string representation of the unsigned integer value
      *          represented by the argument in hexadecimal (base 16).
      * @see #parseUnsignedInt(String, int)
      * @see #toUnsignedString(int, int)
+     * @see #toHexString(int, int)
      * @since   1.0.2
      */
     public static String toHexString(int i) {
         return toUnsignedString0(i, 4);
     }
 
     /**
      * Returns a string representation of the integer argument as an
+     * unsigned integer in base 16, padded with leading zeroes if
+     * necessary.
+     *
+     * <p>The unsigned integer value is the argument plus 2<sup>32</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
+     * Integer#parseUnsignedInt(String, int)
+     * Integer.parseUnsignedInt(s, 16)}.
+     *
+     * <p>If the unsigned magnitude is zero, it is represented by a
+     * {@code minWidth} zero characters {@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 Integer.toHexString(n, 6).toUpperCase()}
+     * </blockquote>
+     *
+     * @param   i        an integer to be converted to a string.
+     * @param   minWidth a minimum required length of the resulting string.
+     * @return  the string representation of the unsigned integer value
+     *          represented by the argument in hexadecimal (base&nbsp;16),
+     *          padded with leading zeroes if necessary.
+     * @see #parseUnsignedInt(String, int)
+     * @see #toUnsignedString(int, int)
+     * @see #toHexString(int)
+     * @since 1.9
+     */
+    public static String toHexString(int i, int minWidth) {
+        return toUnsignedString0(i, 4, minWidth);
+    }
+
+
+    /**
+     * Returns a string representation of the integer argument as an
      * unsigned integer in base&nbsp;8.
      *
      * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
      * if the argument is negative; otherwise, it is equal to the
      * argument.  This value is converted to a string of ASCII digits

@@ -302,11 +353,13 @@
     public static String toBinaryString(int i) {
         return toUnsignedString0(i, 1);
     }
 
     /**
-     * Convert the integer to an unsigned number.
+     * Format an integer (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)
      */
     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);

@@ -317,11 +370,33 @@
         // Use special constructor which takes over "buf".
         return new String(buf, true);
     }
 
     /**
-     * Format a long (treated as unsigned) into a character buffer.
+     * Format an integer (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
+     */
+    private static String toUnsignedString0(int val, int shift, int minWidth) {
+        // assert shift > 0 && shift <=5 : "Illegal shift value";
+        int mag = Integer.SIZE - Integer.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)
+            formatUnsignedInt(val, shift, buf, zeroes, magLen);
+
+        // Use special constructor which takes over "buf".
+        return new String(buf, true);
+    }
+
+    /**
+     * Format an integer (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