How to compare two given dates in Java?



Problem Description :


Write a program in java that compare two given dates with all possible validations.

Concept :


We can compare two dates using following methods of Date class.

1) int compareTo(Date anotherDate) - It returns 3 values 0(zero), positive, negative.
  • 0(zero) -> both dates are equal.
  • positive -> first date comes after second date.
  • negative -> first date comes before second date.
2) boolean after(Date date) - Test if this date is after the specified date.
3) boolean before(Date date) - Test if this date is before the specified date.



Recommended :



Java Program :


package com.javamultiplex.datetime;

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

/**
 * 
 * @author Rohit Agarwal
 * @category Date and Time
 * @problem How to compare two dates
 * 
 */
public class CompareDates {

 public static void main(String[] args) {

  Scanner input = null;
  try {
   input = new Scanner(System.in);
   System.out.println("Enter first date in dd/MM/yyyy format :");
   String first = input.next();
   System.out.println("Enter second date in dd/MM/yyyy format :");
   String second = input.next();
   // If Date is valid, converting String to date.
   Date mydate1 = getValidDate(first);
   Date mydate2 = getValidDate(second);
   if (mydate1 != null && mydate2 != null) {

    if (mydate1.compareTo(mydate2) == 0) {
     System.out.println("Both dates are equal.");
    } else if (mydate1.compareTo(mydate2) > 0) {
     System.out.println("First date comes after second date.");
    } else if (mydate1.compareTo(mydate2) < 0) {
     System.out.println("First date comes before second date.");
    }

   } else {
    System.out.println("Dates are invalid.");
   }
  } finally {
   if (input != null) {
    input.close();
   }
  }

 }

 private static Date getValidDate(String date) {

  Date mydate = null;
  if (isValidDateFormat(date)) {
   /*
    * d -> Day of month 
    * M -> Month of year 
    * y -> Year
    */
   DateFormat dateFormat = new SimpleDateFormat("dd/MM/yyyy");
   /*
    * By default setLenient() is true. We should make it false for
    * strict date validations.
    * 
    * If setLenient() is true - It accepts all dates. If setLenient()
    * is false - It accepts only valid dates.
    */
   dateFormat.setLenient(false);
   try {
    mydate = dateFormat.parse(date);
   } catch (ParseException e) {
    mydate = null;
   }
  }
  return mydate;
 }

 private static boolean isValidDateFormat(String date) {

  /*
   * Regular Expression that matches String with format dd/MM/yyyy. 
   * dd -> 01-31 
   * MM -> 01-12 
   * yyyy -> 4 digit number
   */
  String pattern = "(0?[1-9]|[12][0-9]|3[01])\\/(0?[1-9]|1[0-2])\\/([0-9]{4})";
  boolean result = false;
  if (date.matches(pattern)) {
   result = true;
  }
  return result;
 }

}


Output :


Case 1 :

Output of Java program how to compare two given dates - case1
Output - Both dates are equal

Case 2 :

Output of Java program how to compare two given dates - case2
Output - First date comes before second date


Case 3 :

Output of Java program how to compare two given dates - case3
Output - First date comes after second date

References :






Thank you friends, I hope you have clearly understood the solution of this problem. If you have any doubt, suggestion or query please feel free to comment below. You can also discuss this solution in our forum.

Tags :  Date and Time problems, Date comparison in Java, String, Regular expressions, DateFormat, SimpleDateFormat, if else statement.

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How to compare two given dates in Java? How to compare two given dates in Java? Reviewed by Rohit Agarwal on 11/26/2016 Rating: 5

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