CNPJ / CPF (Federal Tax ID for Brasil) Validator in Java

CNPJValidator.java

public class CNPJValidator {

    public static boolean validateCNPJ(String cnpj) {
        // Remove non-numeric characters
        cnpj = cnpj.replaceAll("[^0-9]", "");

        // Check if CNPJ has 14 digits
        if (cnpj.length() != 14)
            return false;

        // Check if all digits are equal
        boolean allDigitsEqual = true;
        for (int i = 1; i < cnpj.length(); i++) {
            if (cnpj.charAt(i) != cnpj.charAt(0)) {
                allDigitsEqual = false;
                break;
            }
        }
        if (allDigitsEqual)
            return false;

        // Calculate the first verification digit
        int sum = 0;
        int[] weight1 = { 5, 4, 3, 2, 9, 8, 7, 6, 5, 4, 3, 2 };
        for (int i = 0; i < 12; i++) {
            sum += (cnpj.charAt(i) - '0') * weight1[i];
        }
        int digit1 = 11 - (sum % 11);
        if (digit1 >= 10)
            digit1 = 0;

        // Verify the first verification digit
        if (digit1 != cnpj.charAt(12) - '0')
            return false;

        // Calculate the second verification digit
        int[] weight2 = { 6, 5, 4, 3, 2, 9, 8, 7, 6, 5, 4, 3, 2 };
        sum = 0;
        for (int i = 0; i < 13; i++) {
            sum += (cnpj.charAt(i) - '0') * weight2[i];
        }
        int digit2 = 11 - (sum % 11);
        if (digit2 >= 10)
            digit2 = 0;

        // Verify the second verification digit
        if (digit2 != cnpj.charAt(13) - '0')
            return false;

        // Valid CNPJ
        return true;
    }

    public static void main(String[] args) {
        //Sample
        String cnpj = "12.345.678/0001-90";
        if (validateCNPJ(cnpj)) {
            System.out.println("Valid CNPJ");
        } else {
            System.out.println("Invalid CNPJ");
        }
    }
}

CPFValidator.java

public class CPFValidator {
    
    public static boolean validateCPF(String cpf) {
        // Remove non-numeric characters
        cpf = cpf.replaceAll("[^0-9]", "");
        
        // Check if CPF has 11 digits
        if (cpf.length() != 11)
            return false;
        
        // Check if all digits are equal
        boolean allDigitsEqual = true;
        for (int i = 1; i < cpf.length(); i++) {
            if (cpf.charAt(i) != cpf.charAt(0)) {
                allDigitsEqual = false;
                break;
            }
        }
        if (allDigitsEqual)
            return false;
        
        // Calculate the first verification digit
        int sum = 0;
        for (int i = 0; i < 9; i++) {
            sum += (cpf.charAt(i) - '0') * (10 - i);
        }
        int digit1 = 11 - (sum % 11);
        if (digit1 >= 10)
            digit1 = 0;
        
        // Verify the first verification digit
        if (digit1 != cpf.charAt(9) - '0')
            return false;
        
        // Calculate the second verification digit
        sum = 0;
        for (int i = 0; i < 10; i++) {
            sum += (cpf.charAt(i) - '0') * (11 - i);
        }
        int digit2 = 11 - (sum % 11);
        if (digit2 >= 10)
            digit2 = 0;
        
        // Verify the second verification digit
        if (digit2 != cpf.charAt(10) - '0')
            return false;
        
        // Valid CPF
        return true;
    }

    public static void main(String[] args) {
        //Sample
        String cpf = "123.456.789-09";
        if (validateCPF(cpf)) {
            System.out.println("Valid CPF");
        } else {
            System.out.println("Invalid CPF");
        }
    }
}