Validate credit card numbers with the Luhn algorithm in Java

LuhnFormula.java

public class LuhnFormula {
  
  public boolean validate(String input) {
        char[] chars = convertToArrayOfValidChars(input);
        return getSum(chars) % 10 == 0;
    }
  
  private char[] convertToArrayOfValidChars(String input) {
        String sanitized = input.replaceAll("[^\\d]", "");
        return sanitized.toCharArray();
    }
  
  private int getSum(char[] chars) {
        int sum = 0;
        for (int i = 0; i < chars.length; i++) {
            int number = getInReverseOrder(chars, i);
            sum += getElementValue(i, number);
        }
        return sum;
    }
  
  private int getInReverseOrder(char[] chars, int i) {
        int indexInReverseOrder = chars.length - 1 - i;
        char character = chars[indexInReverseOrder];
        return Character.getNumericValue(character);
    }
  
  private int getElementValue(int i, int number) {
        if (i % 2 != 0) {
            return getOddElementValue(number);
        } else {
            return number;
        }
    }
 
    private int getOddElementValue(int element) {
        int value = element * 2;
        if (value <= 9) {
            return value;
        }
        return value - 9;
    }
}

LuhnFormulaTest.java

import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
 
import static org.junit.jupiter.api.Assertions.*;
 
class LuhnFormulaTest {
 
    private LuhnFormula luhnFormula;
 
    @BeforeEach
    void setUp() {
        luhnFormula = new LuhnFormula();
    }
 
    @Test
    void shouldReturnTrueForValidNumbers() {
        assertAll(
                () -> assertTrue(luhnFormula.validate("5277 0291 2077 3860")),
                () -> assertTrue(luhnFormula.validate("4556-0690-9685-2293")),
                () -> assertTrue(luhnFormula.validate("4852789106979220268"))
        );
    }

    @Test
    void shouldReturnFalseForInvalidNumbers() {
        assertAll(
                () -> assertFalse(luhnFormula.validate("4852 7891 0697 922 0261")),
                () -> assertFalse(luhnFormula.validate("3543-6933-8731-4139")),
                () -> assertFalse(luhnFormula.validate("6759310784561226"))
        );
    }
}