TapCardValidator

A robust Android library for validating payment card information in real-time with support for multiple card types and comprehensive error handling.

Features

• ✅ Real-time card number validation
• ✅ Card type detection (Visa, Mastercard, American Express, etc.)
• ✅ Expiry date validation
• ✅ CVV/CVC validation
• ✅ Cardholder name validation
• ✅ Lightweight and efficient
• ✅ Easy-to-integrate API

Installation

Gradle

Add the dependency to your module's build.gradle:

dependencies {
    implementation 'com.tap:cardvalidator:1.0.0'
}

Maven

<dependency>
    <groupId>com.tap</groupId>
    <artifactId>cardvalidator</artifactId>
    <version>1.0.0</version>
</dependency>

Integration Guide

Step 1: Initialize the Validator

import com.tap.cardvalidator.CardValidator

val validator = CardValidator()

Step 2: Validate Card Number

val cardNumber = "4532015112830366"
val isValid = validator.validateCardNumber(cardNumber)

if (isValid) {
    val cardType = validator.detectCardType(cardNumber)
    println("Card Type: $cardType")
} else {
    println("Invalid card number")
}

Step 3: Validate Expiry Date

val month = 12
val year = 25

val isExpiryValid = validator.validateExpiryDate(month, year)
if (isExpiryValid) {
    println("Expiry date is valid")
} else {
    println("Card has expired or invalid format")
}

Step 4: Validate CVV

val cvv = "123"
val cardType = "VISA"

val isCVVValid = validator.validateCVV(cvv, cardType)
if (isCVVValid) {
    println("CVV is valid")
} else {
    println("Invalid CVV")
}

Step 5: Validate Cardholder Name

val cardholderName = "John Doe"

val isNameValid = validator.validateCardholderName(cardholderName)
if (isNameValid) {
    println("Cardholder name is valid")
} else {
    println("Invalid cardholder name")
}

Complete Integration Example

import com.tap.cardvalidator.CardValidator

class PaymentActivity : AppCompatActivity() {
    
    private val validator = CardValidator()
    
    fun processPayment(
        cardNumber: String,
        expiryMonth: Int,
        expiryYear: Int,
        cvv: String,
        cardholderName: String
    ): Boolean {
        // Validate all fields
        if (!validator.validateCardNumber(cardNumber)) {
            showError("Invalid card number")
            return false
        }
        
        if (!validator.validateExpiryDate(expiryMonth, expiryYear)) {
            showError("Invalid expiry date")
            return false
        }
        
        val cardType = validator.detectCardType(cardNumber)
        if (!validator.validateCVV(cvv, cardType)) {
            showError("Invalid CVV")
            return false
        }
        
        if (!validator.validateCardholderName(cardholderName)) {
            showError("Invalid cardholder name")
            return false
        }
        
        // All validations passed
        submitPayment(cardNumber, expiryMonth, expiryYear, cvv, cardholderName)
        return true
    }
    
    private fun showError(message: String) {
        Toast.makeText(this, message, Toast.LENGTH_SHORT).show()
    }
    
    private fun submitPayment(vararg args: Any) {
        // Process payment
    }
}

Supported Card Types

• Visa
• Mastercard
• American Express
• Discover
• Diners Club
• JCB
• Maestro

API Reference

CardValidator

Method	Parameters	Returns	Description
validateCardNumber()	cardNumber: String	Boolean	Validates card number using Luhn algorithm
detectCardType()	cardNumber: String	String	Detects and returns card type
validateExpiryDate()	month: Int, year: Int	Boolean	Validates expiry date
validateCVV()	cvv: String, cardType: String	Boolean	Validates CVV based on card type
validateCardholderName()	name: String	Boolean	Validates cardholder name

Best Practices

1. Always validate on the client side - Provides immediate user feedback
2. Never store card details - Use tokenization for production
3. Validate expiry before processing - Check for expired cards
4. Use appropriate card type validation - CVV length differs by card type
5. Handle validation errors gracefully - Show clear error messages to users
6. Test with multiple card numbers - Use test cards for each type

Testing

Use these test card numbers for development:

Visa:              45xxxxxxxx2830366
Mastercard:        54xxxxxxxxxxxx0000
American Express:  37xxxxxxxxxxxxxx126
Discover:          6xxxxxxxxxxxx7

Troubleshooting

Issue: Card validation always fails

• Solution: Ensure card number is stripped of spaces and hyphens
• Solution: Verify the card number length matches the card type

Issue: CVV validation fails for American Express

• Solution: AmEx CVV is 4 digits, not 3
• Solution: Use the correct card type when validating

Issue: Expiry date validation not working

• Solution: Ensure month is 1-12 and year is valid
• Solution: Use 2-digit year format (e.g., 25 for 2025)

License

This project is licensed under the MIT License - see the LICENSE file for details.

Support

For issues, questions, or contributions, please visit our GitHub repository.