Write a java program to validate Date and Time

Java code to validate a date and time format. There are two different programs one is to validate a Date format “dd/MM/yyyy” and the other is to validate a Time format “hh: mm am” or “hh: mm pm” in Java. Along with validation time in 24 hr format.

Obtain a date string in the format dd/mm/yyyy. Write code to validate the given date against the given format. The return type of the validateDate method is 1 if the given date format matches the specified format. If the validation fails, return the output as -1.

Input and Output Format to validate Date

• Input is a string.
• Output is a string.

Refer sample output for formatting specifications

Sample Input 1:

12/06/1987

Sample Output 1:

Valid date format

Sample Input 2:

03/1/1987

Sample Output 2:

Invalid date format

Program in Java for Validating Date Format

Following are the steps to validate date format in Java:

• Input a string.
• Pass the string to getValues() method.
• Inside the getValues() method, use the regex pattern to match the string.
• Now, create the object of SimpleDateFormat class using the ‘dd/MM/yyyy’ pattern.
• Here, call the setLenient() method with value false.
• Now, use the parse method to validate the date and return 1 if valid else return -1.
• At last, catch this value in a variable n and check if it is 1 then just print “Valid date format” else print  “Invalid date format”.

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
  Scanner sc = new Scanner(System.in);
  String s1 = sc.nextLine();

  int n = getvalues(s1);
  
  if(n==1){
    System.out.println("Valid date format");
  }else{
    System.out.println("Invalid date format");
  }
  
}
public static int getvalues(String s1) {
if(s1.matches("[0-9]{2}[/]{1}[0-9]{2}[/]{1}[0-9]{4}"))
{
SimpleDateFormat sdf=new SimpleDateFormat("dd/MM/yyyy");
sdf.setLenient(false);
try {
Date d1=sdf.parse(s1);
return 1;
} catch (ParseException e) {
return -1;
}
}
else
  return -1;
}}

Output

Validate Time format in Java

Obtain a time string as input in the following format ‘hh:mm am’ or ‘hh:mm pm’. Write code to validate it using the following rules:

• It should be a valid time in 12 hrs format.
• It should have case-insensitive AM or PM.
• If the given time is as per the given rules then return 1 else return -1. If the value returned is 1 then print as valid time else print as Invalid time.

Input and Output Format to validate time format in Java

• Input is a string.
• Output is a string.

Sample Input 1:

09:59 pm

Sample Output 1:

Valid time

Sample Input 2:

10:70 AM

Sample Output 2:

Invalid time

Write a java program to validate the time format in Java

Following are the steps to validate the time format in Java:

• Input a string.
• Now, break the string into tokens by using StringTokenizer class.
• If the count of tokens is equal to 3, then create the object of SimpleDateFormat class with ‘h:mm:ss a’ pattern.
• Set the leniency to false.
• Now, use the parse method to validate the string and print “Valid Time”.
• If the string token count is not equal to 3, then once again create the object of SimpleDateFormat class with “h:mm a” pattern.
• Repeat the above process and print “Valid Time”.

package com.date;

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

public class ValidateTime {

public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
String str = sc.nextLine();
StringTokenizer st = new StringTokenizer(str, ":");
if (st.countTokens() == 3) {
SimpleDateFormat sdf1 = new SimpleDateFormat("h:mm:ss a");
sdf1.setLenient(false);
try {
Date d2 = sdf1.parse(str);
System.out.println("Valid time");
} catch (Exception e) {
System.out.println("Invalid time");
}
} else {
SimpleDateFormat sdf = new SimpleDateFormat("h:mm a");
sdf.setLenient(false);
try {
Date d1 = sdf.parse(str);
System.out.println("Valid time");
} catch (Exception e) {
System.out.println("Invalid time");
}
}
}
}

Output

Validate Time in 24 hr format using regex

Obtain a time string as input in the following format “16:00”. Write code to validate it using the following rules:

• It should start with 0-23 or 00-23.
• It should be followed by ‘:’.
• After this, there should be two digits 00 to 59.
• In the end, it should not be, am, pm, AM, and PM.

Input and Output Format to validate time format in Java

• Input is a string.
• Output is a string.

Sample Input 1:

16:00

Sample Output 1:

Valid time

Sample Input 2:

25:00

Sample Output 2:

Invalid time

Program to validate time in 24 hr using regex in Java

Following are the steps to validate the time in 24 hr format in Java:

• Input time in string.
• Now, match the time with the pattern as shown below

String time = ([01]?[0-9]|2[0-3]):[0-5][0-9];

• • ([01]?[0-9]|2[0-3]) – It represents the start of the pattern.
  • : – It represents that the above pattern should be followed by a colon (:).
  • [0-5][0-9] – It should end with two digits.
• If the pattern is matched then print “Valid time” else print “Invalid time”.

package com.date;

import java.text.SimpleDateFormat;
import java.util.Scanner;
import java.util.StringTokenizer;

public class ValidateTimeFormat {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String time = scanner.next();
        if(time.matches("([01]?[0-9]|2[0-3]):[0-5][0-9]")){
            System.out.println("Valid Time");
        }
        else{
            System.out.println("Invalid Time");
        }
    }
}

Output

Thus, in this way, we learn How to validate time format and date format in Java. Along with validating time in 24 hr format using regex.