DateOperations.java

package com.company;

import java.text.SimpleDateFormat;
import java.util.Date;

/**
 * Created by clara on 4/18/17. Example Date manipulations. 
 */
public class DateOperations {
    public static void main(String[] args) {

        // Use SimpleDateFormat to create a String, in a particular format, from a Date object

        // https://docs.oracle.com/javase/6/docs/api/java/text/SimpleDateFormat.html
        // Use whatever format pattern you want, examples at link above. 
        // // example: 2017_04_18_13_13_16
        String formatPattern = "yyyy_MM_dd_HH_mm_ss"; 
        
        SimpleDateFormat dateFormatter = new SimpleDateFormat(formatPattern);
        Date date = new Date();
        String dateStr = dateFormatter.format(date);
        System.out.println(dateStr);

        // Convert a Date to a timestamp, convert a timestamp to a Date
        // timestamp = number of milliseconds since Midnight UTC, January 1, 1970

        Date now = new Date();
        long timeStamp = now.getTime();
        System.out.println("The timestamp for the current date is " + timeStamp);

        Date fromTimeStamp = new Date(timeStamp);
        System.out.println("A new date object from a timestamp is " + fromTimeStamp);


    }
}