Validation is a process of ensuring that data is correct and complete. It is often used to ensure that user input is in the correct format. Data validation can be done using different techniques, such as:
There are many different ways to validate data. In this article, we will focus on input validation using the Kotlin programming language.
There are many different ways to validate a string. In Kotlin, we can use the isNotBlank()
function to check if a string is not blank. This function returns true
if the string is not blank and false
if the string is blank.
For example, we can use the isNotBlank()
function to check if a string is a valid email address.
fun isValidEmail(email: String): Boolean {
return email.isNotBlank() && email.contains("@")
}
We can also use the isNotEmpty()
function to check if a string is not empty. This function returns true
if the string is not empty and false
if the string is empty.
For example, we can use the isNotEmpty()
function to check if a string is a valid password.
fun isValidPassword(password: String): Boolean {
return password.isNotEmpty() && password.length >= 8
}
There are many different ways to validate a number. In Kotlin, we can use the isDigitsOnly()
function to check if a string is composed of only digits. This function returns true
if the string is composed of only digits and false
if the string is not composed of only digits.
For example, we can use the isDigitsOnly()
function to check if a string is a valid credit card number.
fun isValidCreditCardNumber(creditCardNumber: String): Boolean {
return creditCardNumber.isDigitsOnly() && creditCardNumber.length == 16
}
We can also use the toLong()
function to convert a string to a long. This function returns null
if the string is not a valid long.
For example, we can use the toLong()
function to check if a string is a valid phone number.
fun isValidPhoneNumber(phoneNumber: String): Boolean {
return phoneNumber.toLong() != null && phoneNumber.length == 10
}
There are many different ways to validate a date. In Kotlin, we can use the isValidDate()
function to check if a string is a valid date. This function returns true
if the string is a valid date and false
if the string is not a valid date.
For example, we can use the isValidDate()
function to check if a string is a valid date of birth.
fun isValidDateOfBirth(dateOfBirth: String): Boolean {
return isValidDate(dateOfBirth) && LocalDate.parse(dateOfBirth).isBefore(LocalDate.now())
}
We can also use the isBefore()
function to check if a date is before another date. This function returns true
if the date is before the other date and false
if the date is not before the other date.
For example, we can use the isBefore()
function to check if a date is a valid date of birth.
fun isValidDateOfBirth(dateOfBirth: String): Boolean {
return LocalDate.parse(dateOfBirth).isBefore(LocalDate.now())
}
In this article, we have looked at some of the ways we can validate data using the Kotlin programming language. We have seen how we can use the isNotBlank()
, isNotEmpty()
, isDigitsOnly()
, toLong()
, and isValidDate()
functions to validate strings, numbers, and dates.