How to Validate Date Input from User in Specific Formats in Java?

In Java, validating user-provided dates to ensure a specific format is very important for maintaining data integrity and application functionality. Mainly two commonly used approaches are SimpleDateFormat class and DateTimeFormatter class, which validates the expected date format and parses the user input.

In this article, we will learn how to validate a date input into a specific format in Java.

Methods to Validate a Date Input into a Specific Format

There are mainly two ways to validate a date input to ensure it’s in a specific format in Java.

• Using SimpleDateFormat
• Using java.time.DateTimeFormatter

Below is the code implementation of these two approaches.

Program to Validate a Date Input to Ensure it is in a Specific Format in Java

Below are the two methods implementations to validate a date input to ensure it in a specific format.

Method 1: Using SimpleDateFormat

By using SimpleDateFormat we will validate the date format.

Java

// Java Program to validate a date input to ensure
// It's in a specific format using SimpleDateFormat
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

// Driver Class
public class GFG
{
      // Main Function
    public static void main(String args[])
    {
        String date = "09-02-2024"; // input
        // define the expected date format
        SimpleDateFormat dateFormat
            = new SimpleDateFormat("dd-MM-yyyy");
        // set lenient to false to apply strict date parsing
        dateFormat.setLenient(false);

        try {
            // parse the user input into a Date object
            Date parsedDate = dateFormat.parse(date);
            System.out.println(
                "Valid date format: "
                + dateFormat.format(parsedDate));
        }
        catch (ParseException e) {
            System.out.println(
                "Invalid date format. yyyy-MM-dd.");
        }
    }
}

Output

Valid date format: 09-02-2024

Explanation of the above Program:

In the above Program,

• We have defined the expected date format as "dd-MM-yyyy" using the SimpleDateFormat class.
• We set the lenient property of the dateFormat object to false to enforce strict date parsing.
• The input date string is "09-02-2024".
• We attempt to parse the input string into a Date object using the specified format in a try-catch block.
• If parsing is successful, we print the valid date format. If parsing fails (due to an invalid format), a ParseException is caught, and we print an error message indicating the expected date format (yyyy-MM-dd).

Method 2: Using java.time.DateTimeFormatter

By using DateTimeFormatter class we will validate the date format.

Java

// Java Program to Validate a Date Input to ensure
// It's in a specific format using DateTimeFormatter
import java.time.LocalDate;
import java.time.format.DateTimeFormatter;

// Driver Class
public class GFG
{
      // Main Function
    public static void main(String args[])
    {
        // define the date format
        String dateFormat = "dd/MM/yyyy";
        // create a DateTimeFormatter object with the specified format
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern(dateFormat);

        // input date string
        String input
            = "2024-02-09";

        try {
            // parse the input string to LocalDate using the formatter
            LocalDate date
                = LocalDate.parse(input, formatter);
            // print the valid date
            System.out.println("Valid date: " + date);
        }
        // catch exception if the input format is invalid
        catch (Exception e) {
            // print error message for invalid date format
            System.out.println("Invalid date format: "
                               + input);
        }
    }
}

Output

Invalid date format: 2024-02-09

Explanation of the above Program:

In the above Program,

• We have defined the date format as "dd/MM/yyyy".
• We have created a DateTimeFormatter object named formatter using the DateTimeFormatter.ofPattern method.
• Then we input the date string.
• We attempt to parse the input string into a LocalDate object using the specified formatter in a try-catch block.
• If parsing is successful, we print the valid date. If parsing fails (due to an invalid format), an exception is caught, and we print an error message indicating the invalid date format.