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@javamultiplex
Created September 22, 2017 15:09
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How to check whether given Date is valid or not in Java?
package com.javamultiplex.datetime;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Scanner;
/**
*
* @author Rohit Agarwal
* @category Date and Time
* @problem Check whether date is valid or not?
*
*/
public class DateValid {
/*
* Date is valid if It's format is correct (For ex : dd/MM/yyyy) It exist in
* reality, I mean 30/02/2016 is in correct format but there is not such
* date in reality, So invalid.
*/
public static void main(String[] args) {
Scanner input = null;
try {
input = new Scanner(System.in);
System.out.println("Enter date in dd/MM/yyyy format : ");
String date = input.next();
if (isDateValid(date)) {
System.out.println("Date is valid.");
} else {
System.out.println("Date is not valid.");
}
} finally {
if (input != null) {
input.close();
}
}
}
private static boolean isDateValid(String date) {
boolean result = false;
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 {
dateFormat.parse(date);
result = true;
} catch (ParseException e) {
result = false;
}
}
return result;
}
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;
}
}
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