From 6d407f88a339f6ef905063096de21f266a41d020 Mon Sep 17 00:00:00 2001
From: iaforek <arkadiusz@jaworski.pl>
Date: Tue, 30 May 2017 09:57:12 +0100
Subject: [PATCH] BAEL-821 New class that shows different rounding techniques.
 Updated POM.

---
 core-java/pom.xml                             |  7 ++++
 .../main/java/com/baeldung/maths/Round.java   | 38 +++++++++++++++++++
 2 files changed, 45 insertions(+)
 create mode 100644 core-java/src/main/java/com/baeldung/maths/Round.java

diff --git a/core-java/pom.xml b/core-java/pom.xml
index bcec20b1e1..5c9bf06a57 100644
--- a/core-java/pom.xml
+++ b/core-java/pom.xml
@@ -45,6 +45,12 @@
 			<artifactId>commons-math3</artifactId>
 			<version>${commons-math3.version}</version>
 		</dependency>
+		
+		<dependency>
+    		<groupId>org.decimal4j</groupId>
+    		<artifactId>decimal4j</artifactId>
+    		<version>${decimal4j.version}</version>
+		</dependency>
 
 		<dependency>
 			<groupId>org.bouncycastle</groupId>
@@ -369,6 +375,7 @@
 		<bouncycastle.version>1.55</bouncycastle.version>
 		<commons-codec.version>1.10</commons-codec.version>
 		<commons-math3.version>3.6.1</commons-math3.version>
+		<decimal4j.version>1.0.3</decimal4j.version>
 		<commons-io.version>2.5</commons-io.version>
 		<commons-collections4.version>4.1</commons-collections4.version>
 		<collections-generic.version>4.01</collections-generic.version>
diff --git a/core-java/src/main/java/com/baeldung/maths/Round.java b/core-java/src/main/java/com/baeldung/maths/Round.java
new file mode 100644
index 0000000000..3b30ab2c7a
--- /dev/null
+++ b/core-java/src/main/java/com/baeldung/maths/Round.java
@@ -0,0 +1,38 @@
+package com.baeldung.maths;
+
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+import java.text.DecimalFormat;
+
+import org.apache.commons.math3.util.Precision;
+import org.decimal4j.util.DoubleRounder;
+
+public class Round {
+    private static final double PI = 3.1415d;
+    
+    public static void main (String args[]) {
+        System.out.println("PI: " + PI);
+        System.out.printf("Value with 3 digits after decimal point %.3f %n", PI);
+        // OUTPUTS: Value with 3 digits after decimal point 3.142
+        DecimalFormat df = new DecimalFormat("###.###");
+        System.out.println(df.format(PI));
+        System.out.println(round(PI, 3));
+        System.out.println(roundOptional(PI, 3));
+        System.out.println(Precision.round(PI, 3));
+        System.out.println(DoubleRounder.round(PI, 3));
+    }
+    
+    public static double round(double value, int places) {
+        if (places < 0) throw new IllegalArgumentException();
+        
+        BigDecimal bd = new BigDecimal(value);
+        bd = bd.setScale(places, RoundingMode.HALF_UP);
+        return bd.doubleValue();
+    }
+    
+    public static double roundOptional(double value, int places) {
+        double scale = Math.pow(10, places);
+        double rounded = Math.round(value * scale) / scale;
+        return rounded;
+    }
+}