create java-dates-2 module

java-dates-2/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>com.baeldung</groupId>
+    <artifactId>java-dates-2</artifactId>
+    <version>1.0-SNAPSHOT</version>
+
+    <dependencies>
+        <dependency>
+            <groupId>joda-time</groupId>
+            <artifactId>joda-time</artifactId>
+            <version>${joda-time.version}</version>
+        </dependency>
+    </dependencies>
+
+<properties>
+<joda-time.version>2.10</joda-time.version>
+
+<maven.compiler.source>1.8</maven.compiler.source>
+<maven.compiler.target>1.8</maven.compiler.target>
+</properties>
+
+</project>

java-dates-2/src/main/java/ConvertDateTime.java

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+import org.joda.time.Instant;
+
+import java.time.LocalDateTime;
+import java.time.ZoneId;
+import java.time.ZonedDateTime;
+import java.util.Calendar;
+import java.util.Date;
+
+public class ConvertDateTime {
+
+    public static void main(String[] args) {
+
+        java8();
+        joda();
+        Date date = coreDate();
+        calendar(date);
+    }
+
+    private static Date coreDate() {
+        Date date = new Date();
+
+        System.out.println("Date - Time in milliseconds : " + date.getTime());
+
+        return date;
+    }
+
+    private static void calendar(Date date) {
+        Calendar calendar = Calendar.getInstance();
+        calendar.setTime(date);
+        System.out.println("Calender - Time in milliseconds : " + calendar.getTimeInMillis());
+    }
+
+    private static void joda() {
+        org.joda.time.DateTime jodaDateTime = new org.joda.time.DateTime();
+        long delta = jodaDateTime.getMillis();
+        System.out.println("Joda - Time in milliseconds : " + delta);
+
+        Instant jodaInstant = Instant.now();
+        System.out.println("Joda - Instant in milliseconds : " + jodaInstant.getMillis());
+    }
+
+    private static void java8() {
+        long instantMillis = java.time.Instant.now().toEpochMilli();
+
+        LocalDateTime localDateTime = LocalDateTime.now();
+        ZoneId id = ZoneId.systemDefault();
+        ZonedDateTime zdt = ZonedDateTime.of(localDateTime, id);
+        System.out.println("Java 8 - Time in milliseconds : " + zdt.toInstant().toEpochMilli());
+    }
+}