8177552: Compact Number Formatting support

Reviewed-by: naoto, rriggs

src/java.base/share/classes/java/text/spi/NumberFormatProvider.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2005, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2005, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -110,4 +110,37 @@ public abstract class NumberFormatProvider extends LocaleServiceProvider {
      * @see java.text.NumberFormat#getPercentInstance(java.util.Locale)
      */
     public abstract NumberFormat getPercentInstance(Locale locale);
+
+    /**
+     * Returns a new {@code NumberFormat} instance which formats
+     * a number in its compact form for the specified
+     * {@code locale} and {@code formatStyle}.
+     *
+     * @implSpec The default implementation of this method throws
+     * {@code UnSupportedOperationException}. Overriding the implementation
+     * of this method returns the compact number formatter instance
+     * of the given {@code locale} with specified {@code formatStyle}.
+     *
+     * @param locale the desired locale
+     * @param formatStyle the style for formatting a number
+     * @throws NullPointerException if {@code locale} or {@code formatStyle}
+     *     is {@code null}
+     * @throws IllegalArgumentException if {@code locale} is not
+     *     one of the locales returned from
+     *     {@link java.util.spi.LocaleServiceProvider#getAvailableLocales()
+     *     getAvailableLocales()}.
+     * @return a compact number formatter
+     *
+     * @see java.text.NumberFormat#getCompactNumberInstance(Locale,
+     *                      NumberFormat.Style)
+     * @since 12
+     */
+    public NumberFormat getCompactNumberInstance(Locale locale,
+            NumberFormat.Style formatStyle) {
+        throw new UnsupportedOperationException(
+                "The " + this.getClass().getName() + " should override this"
+                + " method to return compact number format instance of "
+                + locale + " locale and " + formatStyle + " style.");
+    }
+
 }