Difference between two dates in java

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

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+package com.baeldung;
+
+import org.joda.time.DateTime;
+import org.junit.Test;
+
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.time.ZonedDateTime;
+import java.util.Date;
+import java.util.Locale;
+import java.util.TimeZone;
+
+import static org.junit.Assert.assertEquals;
+
+public class DateDiffTest {
+    @Test
+    public void givenTwoDatesBeforeJava8SeparatedBySixDays_whenCallingDiffOnThem_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 diff = dateDiff.beforeJava8diff(firstDate, secondDate);
+
+        assertEquals(diff, 6);
+    }
+
+    @Test
+    public void givenTheCurrentDateAndSixDaysBehindInJava8_whenCallingDiffOnThem_thenWeGetSix() {
+        ZonedDateTime now = ZonedDateTime.now();
+        ZonedDateTime sixDaysBehind = now.minusDays(6);
+
+        DateDiff dateDiff = new DateDiff();
+        long diff = dateDiff.fromJava8Diff(now, sixDaysBehind);
+
+        assertEquals(diff, 6);
+    }
+
+    @Test
+    public void givenTheCurrentDateAndSixDaysBehindInJodaTime_whenCallingDiffOnThem_thenWeGetSix() {
+        DateTime now = DateTime.now();
+        DateTime sixDaysBehind = now.minusDays(6);
+
+        DateDiff dateDiff = new DateDiff();
+        long diff = dateDiff.fromJodaTime(now, sixDaysBehind);
+
+        assertEquals(diff, 6);
+    }
+
+    @Test
+    public void givenTheCurrentDateAndSixDaysBehindInDate4j_whenCallingDiffOnThem_thenWeGetSix() {
+        hirondelle.date4j.DateTime now = hirondelle.date4j.DateTime.now(TimeZone.getDefault());
+        hirondelle.date4j.DateTime sixDaysBehind = now.minusDays(6);
+
+        DateDiff dateDiff = new DateDiff();
+        long diff = dateDiff.fromDate4j(now, sixDaysBehind);
+
+        assertEquals(diff, 6);
+    }
+}