src/java.base/share/classes/java/text/NumberFormat.java

@@ -238,12 +238,18 @@
      * This may result in loss of magnitude information and precision for
      * <code>BigInteger</code> and <code>BigDecimal</code> values.
      * @param number     the number to format
      * @param toAppendTo the <code>StringBuffer</code> to which the formatted
      *                   text is to be appended
-     * @param pos        On input: an alignment field, if desired.
-     *                   On output: the offsets of the alignment field.
+     * @param pos        keeps track on the position of the field within the
+     *                   returned string. For example, for formatting a number
+     *                   {@code 1234567.89} in {@code Locale.US} locale,
+     *                   if the given {@code fieldPosition} is
+     *                   {@link NumberFormat#INTEGER_FIELD}, the begin index
+     *                   and end index of {@code fieldPosition} will be set
+     *                   to 0 and 9, respectively for the output string
+     *                   {@code 1,234,567.89}.
      * @return           the value passed in as <code>toAppendTo</code>
      * @exception        IllegalArgumentException if <code>number</code> is
      *                   null or not an instance of <code>Number</code>.
      * @exception        NullPointerException if <code>toAppendTo</code> or
      *                   <code>pos</code> is null

@@ -340,11 +346,18 @@
      * Specialization of format.
      *
      * @param number     the double number to format
      * @param toAppendTo the StringBuffer to which the formatted text is to be
      *                   appended
-     * @param pos        the field position
+     * @param pos        keeps track on the position of the field within the
+     *                   returned string. For example, for formatting a number
+     *                   {@code 1234567.89} in {@code Locale.US} locale,
+     *                   if the given {@code fieldPosition} is
+     *                   {@link NumberFormat#INTEGER_FIELD}, the begin index
+     *                   and end index of {@code fieldPosition} will be set
+     *                   to 0 and 9, respectively for the output string
+     *                   {@code 1,234,567.89}.
      * @return the formatted StringBuffer
      * @exception        ArithmeticException if rounding is needed with rounding
      *                   mode being set to RoundingMode.UNNECESSARY
      * @see java.text.Format#format
      */

@@ -356,11 +369,18 @@
      * Specialization of format.
      *
      * @param number     the long number to format
      * @param toAppendTo the StringBuffer to which the formatted text is to be
      *                   appended
-     * @param pos        the field position
+     * @param pos        keeps track on the position of the field within the
+     *                   returned string. For example, for formatting a number
+     *                   {@code 123456789} in {@code Locale.US} locale,
+     *                   if the given {@code fieldPosition} is
+     *                   {@link NumberFormat#INTEGER_FIELD}, the begin index
+     *                   and end index of {@code fieldPosition} will be set
+     *                   to 0 and 11, respectively for the output string
+     *                   {@code 123,456,789}.
      * @return the formatted StringBuffer
      * @exception        ArithmeticException if rounding is needed with rounding
      *                   mode being set to RoundingMode.UNNECESSARY
      * @see java.text.Format#format
      */