ConditionException

import java.util.ArrayList;

public class ConditionException {

    public static final int DATA_SIZE = 10;
    public static final int DATA_AMOUNT = 10000000;
    public static final double ERROR_FREQUENCY = 0.0001;

    public static void main(String[] args) {
    System.out.print("Creating test data... ");
    ArrayList<String[]> testData = generateData();
    System.out.print("Done!\n");
    System.out.println("Starting tests...");

    // Validation
    long startTime = System.currentTimeMillis();
    for (String[] data : testData) {
        if (isValid(data)) {
        sum(data);
        }
    }
    long endTime = System.currentTimeMillis();
    long firstDuration = endTime - startTime;

    // Exception
    int exceptions = 0;
    startTime = System.currentTimeMillis();
    for (String[] data : testData) {
        try {
        sum(data);
        } catch (Exception e) {
        exceptions++;
        }
    }
    endTime = System.currentTimeMillis();
    long secondDuration = endTime - startTime;

    System.out.println("With validation: " + firstDuration + " ms.");
    System.out.println("With exceptions: " + secondDuration + "ms. Caught " + exceptions + " exceptions.");


    }

    public static boolean isValid(String[] data) {
    for (String item : data) {
        if (!Character.isDigit(item.charAt(1)))
        return false;
    }
    return true;
    }

    public static int sum(String[] data) {
    int sum = 0;
    for (String item : data) {
        sum += Integer.parseInt(item.substring(0, 2));
    }
    return sum;
    }

    public static ArrayList<String[]> generateData() {
    ArrayList<String[]> dataArray = new ArrayList<>();
    for (int i = 0; i < DATA_AMOUNT; i++) {
        dataArray.add(createData());
    }
    return dataArray;
    }

    public static String[] createData() {
    String[] data = new String[DATA_SIZE];
    for (int i = 0; i < DATA_SIZE; i++) {
        if (Math.random() > ERROR_FREQUENCY)
        data[i] = "12valid data";
        else
        data[i] = "invalid data";
    }
    return data;
    }
}