Demonstrate CompactNumberFormat

Nicolai Parlog · Nicolai Parlog · commit ea6a53bab6b1 · 2019-03-18T14:48:30.000+01:00
diff --git a/README.md b/README.md
@@ -84,6 +84,7 @@ Check out the [jpms](http://blog.codefx.org/tag/jpms/) tag on my blog, [this dem
 
 ## Updated APIs
 
+* ⑫ [formating numbers](src/main/java/org/codefx/demo/java12/api/format)
 * ⑪ [`String`](src/main/java/org/codefx/demo/java11/api/string) ([article](https://blog.codefx.org/java/java-11-gems/))
 * ⑪ [I/O](src/main/java/org/codefx/demo/java11/api/io) ([article](https://blog.codefx.org/java/java-11-gems/))
 * ⑪ [`Predicate` / `Pattern`](src/main/java/org/codefx/demo/java11/api/predicate) ([article](https://blog.codefx.org/java/java-11-gems/))
diff --git a/src/main/java/org/codefx/demo/java12/api/format/CompactFormat.java b/src/main/java/org/codefx/demo/java12/api/format/CompactFormat.java
@@ -0,0 +1,39 @@
+package org.codefx.demo.java12.api.format;
+
+import java.text.NumberFormat;
+import java.text.NumberFormat.Style;
+import java.util.Locale;
+
+public class CompactFormat {
+
+	public static void main(String[] args) {
+		followers();
+		decimalPowers();
+	}
+
+	private static void followers() {
+		NumberFormat followers = NumberFormat
+				.getCompactNumberInstance(new Locale("en", "US"), Style.SHORT);
+		followers.setMaximumFractionDigits(1);
+		System.out.println(followers.format(5412) + " followers");
+	}
+
+	private static void decimalPowers() {
+		NumberFormat shortened = NumberFormat
+				.getCompactNumberInstance(new Locale("en", "US"), Style.SHORT);
+		NumberFormat shortenedWithFraction = NumberFormat
+				.getCompactNumberInstance(new Locale("en", "US"), Style.SHORT);
+		shortenedWithFraction.setMaximumFractionDigits(1);
+
+		for (int exp = 0; exp <= 12; exp++)
+			for (int secondDigit : new int[]{ 4, 5 }) {
+				double number = Math.pow(10, exp) + secondDigit * Math.pow(10, exp - 1);
+				System.out.printf(
+						"%,f ~> %s / %s%n",
+						number,
+						shortened.format(number),
+						shortenedWithFraction.format(number));
+			}
+	}
+
+}
