Intersection of 2 arrays

package com.company;

import java.util.Arrays;

public class Algorithm {
    int intersection(int[] arr1, int[] arr2) {
        if (arr1.length == 0 || arr2.length == 0) {
            throw new RuntimeException("Invalid length");
        }
        Arrays.sort(arr1);
        Arrays.sort(arr2);
        int arr1Indx = 0;
        int arr2Indx = 0;
        while (arr1Indx < arr1.length - 1 && arr2Indx < arr2.length - 1) {
            if (arr1[arr1Indx] == arr2[arr2Indx]) {
                return arr1[arr1Indx];
            } else if (arr1[arr1Indx] > arr2[arr2Indx]) {
                arr2Indx++;
            } else {
                arr1Indx++;
            }
        }
        throw new RuntimeException("no intersection");
    }
}

package com.company;

import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;

public class AlgorithmTest {
    @Test
    void largestAndSmallest1() {
        Algorithm algorithm = new Algorithm();
        int[] array1 = new int[]{2, 9, 6, 0, 6, 4, 2};
        int[] array2 = new int[]{1, 5, 7, 0, 8, 3, 4};
        int intersection = algorithm.intersection(array1, array2);
        Assertions.assertEquals(0, intersection);
    }

    @Test
    void largestAndSmallest2() {
        Algorithm algorithm = new Algorithm();
        int[] array1 = new int[]{10, 3, 5, 5, 0, 1, 10};
        int[] array2 = new int[]{1, 7, 2, 8, 3, 4, 5};
        int intersection = algorithm.intersection(array1, array2);
        Assertions.assertEquals(1, intersection);
    }

    @Test
    void largestAndSmallest3() {
        Algorithm algorithm = new Algorithm();
        int[] array1 = new int[]{10, 3, 5, 5, 0, 1, -20};
        int[] array2 = new int[]{1, 7, 2, 8, 3, 4, 5, -20};
        int intersection = algorithm.intersection(array1, array2);
        Assertions.assertEquals(-20, intersection);
    }
}

plugins {
    id 'java'
}

group 'org.example'
version '1.0-SNAPSHOT'

repositories {
    mavenCentral()
}

dependencies {
    testImplementation('org.junit.jupiter:junit-jupiter:5.6.2')
}

test {
    useJUnitPlatform()
}