Author: puneet

How to convert milliseconds to a date format in java

puneetLeave a comment

In java, Date() class has constructor Date(long milliseconds) that provides the a Date class object for the given milliseconds since January 1, 1970, 00:00:00 GMT.

Below is the the program to convert milliseconds to date in java:

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

public class MillisToDateCoverter {

	public static void main(String[] args) {
        long milliSeconds = 1560672963853L; 
  
        //Creates a simple date format 
        DateFormat dateFormat = new SimpleDateFormat("dd MMM yyyy HH:mm:ss"); 
        //Create date from milliseconds
        Date date = new Date(milliSeconds); 
        //Parse the date using dateFormat
        System.out.println("Date:" + dateFormat.format(date)); 
    } 
}

Output:

Date:16 Jun 2019 13:46:03

  1. First of all, a object of SimpleDateFormat class has to be created by given date format.
  2. Pass the milliseconds to Date class to get date object for the given milliseconds since January 1, 1970, 00:00:00 GMT.
  3. Pass created date object to dateFormat object to format it.

How to stop execution for certain time in java

puneetLeave a comment

Sometimes we face the situation where execution of program needs delay or need to stop the program execution for some time. Here are some approaches those perform this delay.

1. Using TimeUnit’s sleep() method

TimeUnit is part of java.util.concurrent.TimeUnit package. TimeUnit is enum class having different units like DAYS,MINUTES,SECONDS and converts the passed value in time unit.
Below example shows how to delay the execution of program by passed value to TimeUnit.SECONDS. 

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.concurrent.TimeUnit;

public class TimeUnitSleepExecution {

	public static void main(String[] args) {
		long startTime = System.currentTimeMillis();
		System.out.println("Execution starts at: " + convertMsToDate(startTime));
		try {
			//Pause for 5 seconds
			TimeUnit.SECONDS.sleep(5);
		} catch (InterruptedException e) {
			System.out.println("Exception:" + e.getMessage());
		}
		//Prints current time after 5 seconds only
		long endTime = System.currentTimeMillis();
		System.out.println("Execution starts at: " + convertMsToDate(endTime));
	}
	
	private static String convertMsToDate(long milliseconds) {
		//Creates a simple date format 
        DateFormat dateFormat = new SimpleDateFormat("dd MMM yyyy HH:mm:ss"); 
        //Create date from milliseconds
        Date date = new Date(milliseconds); 
        //Parse the date using dateFormat
        return dateFormat.format(date);
	}

}

In above code, TimeUnit.SECONDS.sleep(5) will hold the execution for 5 seconds, next statements will be executed after when execution resumes.

Output:

Execution starts at: 16 Jun 2019 16:13:44
Execution starts at: 16 Jun 2019 16:13:49

2. Using Thread.sleep() method

Second approach of delay execution is Thread.sleep( long millis) method that takes only time in milliseconds.
Below example shows how to delay the execution of program using sleep method of Thread. 

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

public class ThreadSleepExecution {

	public static void main(String[] args) {
		try {
			System.out.println("Execution starts at: " + convertMsToDate(System.currentTimeMillis()));//statement 1
			//Pause for 5 seconds
			Thread.sleep(5000);
			//Prints current time after 5 seconds only
			System.out.println("Execution ends at: " + convertMsToDate(System.currentTimeMillis())); //statement 2
		} catch (InterruptedException e) {
			System.out.println("Exception:" + e.getMessage());
		}
	}
	
	private static String convertMsToDate(long milliseconds) {
		//Creates a simple date format 
        DateFormat dateFormat = new SimpleDateFormat("dd MMM yyyy HH:mm:ss"); 
        //Create date from milliseconds
        Date date = new Date(milliseconds); 
        //Parse the date using dateFormat
        return dateFormat.format(date);
	}

}

In above code, Thread.sleep(5000) will hold the execution for 5 seconds, Statement 2 will be executed after that only when execution resumes.

Execution starts at: 16 Jun 2019 16:15:45
Execution ends at: 16 Jun 2019 16:15:50