Sum is the number of s (Java)

Sum is the number of s (Java)

Problem: Enter an ascending sorted array and a number S, find two numbers in the array so that their sum is exactly S, if the sum of multiple pairs of numbers is equal to S, output the smallest product of the two numbers.
Code:

import java.util.ArrayList;

/**
 * @desc 和为s的两个数
 * @author zhaoliang
 * @date 20200418
 */
public class Main57 {
    //输入一个递增排序的数组和一个数字S，在数组中查找两个数，使得他们的和正好是S，
    // 如果有多对数字的和等于S，输出两个数的乘积最小的。
    public ArrayList<Integer> FindNumbersWithSum(int [] array, int sum) {

        ArrayList<Integer> list =new ArrayList<>();
        int ahead = 0;
        int behind = array.length - 1;
        while (ahead <=behind){
            if (array[ahead] + array[behind] == sum){
                list.add(array[ahead]);
                list.add(array[behind]);
                break;
            }else if(array[ahead] + array[behind] < sum ){
                ahead ++;
            }else {
                behind --;
            }
        }
        return list;
    }
}