Main.java

import java.util.*;
import java.lang.*;

class Solution {
    /**
    Given two positive integers a and b, return the even digits between a
    and b, in ascending order.

    For example:
    generateIntegers(2, 8) => [2, 4, 6, 8]
    generateIntegers(8, 2) => [2, 4, 6, 8]
    generateIntegers(10, 14) => []
     */
    public List<Integer> generateIntegers(int a, int b) {

        int lower = Math.max(2, Math.min(a, b));
        int upper = Math.min(8, Math.max(a, b));

        List<Integer> result = new ArrayList<>();
        for (int i = lower; i < upper; i += 2) {
            result.add(i);
        }
        return result;
    }
}
public class Main {
    public static void main(String[] args) {
        Solution s = new Solution();
        List<Boolean> correct = Arrays.asList(
                s.generateIntegers(2, 8).equals(Arrays.asList(2, 4, 6, 8)),
                s.generateIntegers(8, 2).equals(Arrays.asList(2, 4, 6, 8)),
                s.generateIntegers(10, 14).equals(List.of())
        );
        if (correct.contains(false)) {
            throw new AssertionError();
        }
    }
}