Simple clean of difference between dates

core-java/README.md

@@ -141,3 +141,6 @@
 - [Guide to UUID in Java](http://www.baeldung.com/java-uuid)
 - [How to Get the Last Element of a Stream in Java?](http://www.baeldung.com/java-stream-last-element)
 - [Guide to Escaping Characters in Java RegExps](http://www.baeldung.com/java-regexp-escape-char)
+- [Period and Duration in Java](http://www.baeldung.com/java-period-duration)
+- [Introduction to the Java 8 Date/Time API](http://www.baeldung.com/java-8-date-time-intro)
+- [Migrating to the New Java 8 Date Time API](http://www.baeldung.com/migrating-to-java-8-date-time-api)

core-java/pom.xml

@@ -186,6 +186,16 @@
             <artifactId>fscontext</artifactId>
             <version>${fscontext.version}</version>
         </dependency>
+        <dependency>
+            <groupId>joda-time</groupId>
+            <artifactId>joda-time</artifactId>
+            <version>${joda-time.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.darwinsys</groupId>
+            <artifactId>hirondelle-date4j</artifactId>
+            <version>${hirondelle-date4j.version}</version>
+        </dependency>
     </dependencies>
 
     <build>
@@ -408,6 +418,8 @@
         <grep4j.version>1.8.7</grep4j.version>
         <lombok.version>1.16.12</lombok.version>
         <fscontext.version>4.6-b01</fscontext.version>
+        <joda-time.version>2.9.9</joda-time.version>
+        <hirondelle-date4j.version>1.5.1</hirondelle-date4j.version>
 
         <!-- testing -->
         <org.hamcrest.version>1.3</org.hamcrest.version>
@@ -416,9 +428,9 @@
         <assertj.version>3.6.1</assertj.version>
         <avaitility.version>1.7.0</avaitility.version>
 
+
         <!-- maven plugins -->
         <maven-compiler-plugin.version>3.6.0</maven-compiler-plugin.version>
         <maven-surefire-plugin.version>2.19.1</maven-surefire-plugin.version>
-
     </properties>
 </project>

core-java/src/test/java/com/baeldung/DateDiffUnitTest.java

@@ -0,0 +1,63 @@
+package com.baeldung;
+
+import org.joda.time.DateTime;
+import org.junit.Test;
+
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.time.Duration;
+import java.time.ZonedDateTime;
+import java.util.Date;
+import java.util.Locale;
+import java.util.TimeZone;
+import java.util.concurrent.TimeUnit;
+
+import static org.junit.Assert.assertEquals;
+
+public class DateDiffUnitTest {
+
+    @Test
+    public void givenTwoDatesBeforeJava8_whenDifferentiating_thenWeGetSix() throws ParseException {
+        SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy", Locale.ENGLISH);
+        Date firstDate = sdf.parse("06/24/2017");
+        Date secondDate = sdf.parse("06/30/2017");
+
+        long diffInMillies = Math.abs(secondDate.getTime() - firstDate.getTime());
+        long diff = TimeUnit.DAYS.convert(diffInMillies, TimeUnit.MILLISECONDS);
+
+        assertEquals(diff, 6);
+    }
+
+    @Test
+    public void givenTwoDatesInJava8_whenDifferentiating_thenWeGetSix() {
+        ZonedDateTime now = ZonedDateTime.now();
+        ZonedDateTime sixDaysBehind = now.minusDays(6);
+
+        Duration duration = Duration.between(now, sixDaysBehind);
+        long diff = Math.abs(duration.toDays());
+
+        assertEquals(diff, 6);
+    }
+
+    @Test
+    public void givenTwoDatesInJodaTime_whenDifferentiating_thenWeGetSix() {
+        DateTime now = DateTime.now();
+        DateTime sixDaysBehind = now.minusDays(6);
+
+        org.joda.time.Duration duration = new org.joda.time.Duration(now, sixDaysBehind);
+        long diff = Math.abs(duration.getStandardDays());
+
+        assertEquals(diff, 6);
+    }
+
+    @Test
+    public void givenTwoDatesInDate4j_whenDifferentiating_thenWeGetSix() {
+        hirondelle.date4j.DateTime now = hirondelle.date4j.DateTime.now(TimeZone.getDefault());
+        hirondelle.date4j.DateTime sixDaysBehind = now.minusDays(6);
+
+        long diff = Math.abs(now.numDaysFrom(sixDaysBehind));
+
+        assertEquals(diff, 6);
+    }
+
+}

java-difference-date/src/main/java/com/baeldung/DateDiff.java

@@ -1,30 +0,0 @@
-package com.baeldung;
-
-import org.joda.time.DateTime;
-
-import java.time.Duration;
-import java.time.ZonedDateTime;
-import java.util.Date;
-import java.util.concurrent.TimeUnit;
-
-public class DateDiff {
-    public long beforeJava8diff(Date firstDate, Date secondDate){
-        long diffInMillies = Math.abs(secondDate.getTime() - firstDate.getTime());
-        return TimeUnit.DAYS.convert(diffInMillies, TimeUnit.MILLISECONDS);
-    }
-
-    public long fromJava8Diff(ZonedDateTime firstDate, ZonedDateTime secondDate){
-        Duration duration = Duration.between(firstDate, secondDate);
-        return Math.abs(duration.toDays());
-    }
-
-    public long fromJodaTime(DateTime firstDate, DateTime secondDate){
-        org.joda.time.Duration duration = new org.joda.time.Duration(firstDate, secondDate);
-        return Math.abs(duration.getStandardDays());
-    }
-
-    public long fromDate4j(hirondelle.date4j.DateTime firstDate, hirondelle.date4j.DateTime secondDate){
-        long diff = firstDate.numDaysFrom(secondDate);
-        return Math.abs(diff);
-    }
-}

java-difference-date/src/test/java/com/baeldung/DateDiffTest.java

@@ -5,55 +5,56 @@ import org.junit.Test;
 
 import java.text.ParseException;
 import java.text.SimpleDateFormat;
+import java.time.Duration;
 import java.time.ZonedDateTime;
 import java.util.Date;
 import java.util.Locale;
 import java.util.TimeZone;
+import java.util.concurrent.TimeUnit;
 
 import static org.junit.Assert.assertEquals;
 
 public class DateDiffTest {
     @Test
-    public void givenTwoDatesBeforeJava8SeparatedBySixDays_whenCallingDiffOnThem_thenWeGetSix() throws ParseException {
+    public void givenTwoDatesBeforeJava8_whenDifferentiating_thenWeGetSix() throws ParseException {
         SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy", Locale.ENGLISH);
         Date firstDate = sdf.parse("06/24/2017");
         Date secondDate = sdf.parse("06/30/2017");
 
-        DateDiff dateDiff = new DateDiff();
+        long diffInMillies = Math.abs(secondDate.getTime() - firstDate.getTime());
-        long diff = dateDiff.beforeJava8diff(firstDate, secondDate);
+        long diff = TimeUnit.DAYS.convert(diffInMillies, TimeUnit.MILLISECONDS);
 
         assertEquals(diff, 6);
     }
 
     @Test
-    public void givenTheCurrentDateAndSixDaysBehindInJava8_whenCallingDiffOnThem_thenWeGetSix() {
+    public void givenTwoDatesInJava8_whenDifferentiating_thenWeGetSix() {
         ZonedDateTime now = ZonedDateTime.now();
         ZonedDateTime sixDaysBehind = now.minusDays(6);
 
-        DateDiff dateDiff = new DateDiff();
+        Duration duration = Duration.between(now, sixDaysBehind);
-        long diff = dateDiff.fromJava8Diff(now, sixDaysBehind);
+        long diff = Math.abs(duration.toDays());
 
         assertEquals(diff, 6);
     }
 
     @Test
-    public void givenTheCurrentDateAndSixDaysBehindInJodaTime_whenCallingDiffOnThem_thenWeGetSix() {
+    public void givenTwoDatesInJodaTime_whenDifferentiating_thenWeGetSix() {
         DateTime now = DateTime.now();
         DateTime sixDaysBehind = now.minusDays(6);
 
-        DateDiff dateDiff = new DateDiff();
+        org.joda.time.Duration duration = new org.joda.time.Duration(now, sixDaysBehind);
-        long diff = dateDiff.fromJodaTime(now, sixDaysBehind);
+        long diff = Math.abs(duration.getStandardDays());
 
         assertEquals(diff, 6);
     }
 
     @Test
-    public void givenTheCurrentDateAndSixDaysBehindInDate4j_whenCallingDiffOnThem_thenWeGetSix() {
+    public void givenTwoDatesInDate4j_whenDifferentiating_thenWeGetSix() {
         hirondelle.date4j.DateTime now = hirondelle.date4j.DateTime.now(TimeZone.getDefault());
         hirondelle.date4j.DateTime sixDaysBehind = now.minusDays(6);
 
-        DateDiff dateDiff = new DateDiff();
+        long diff = Math.abs(now.numDaysFrom(sixDaysBehind));
-        long diff = dateDiff.fromDate4j(now, sixDaysBehind);
 
         assertEquals(diff, 6);
     }

pom.xml

@@ -76,7 +76,6 @@
         <module>immutables</module>
 
         <module>jackson</module>
-        <module>java-difference-date</module>
         <!--         <module>java-cassandra</module> -->
         <module>vavr</module>
         <module>javax-servlets</module>