This program reads a lot of integers, in which may be duplicated numbers. The program picks out all the duplicated ones and sorts the remainders in a descendent order. 函数接口定义： public static ArrayList<Integer> pick(ArrayList<Integer> a); a is the ArrayLis

t containing the integers to be processed. The function should return an ArrayList<Integer> with all the duplicated numbers removed and the remaining numbers sorted in a descending order.

以下是可能的实现方式：

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;

public class Duplicates {
    public static ArrayList<Integer> pick(ArrayList<Integer> a) {
        // Use HashSet to remove duplicates
        HashSet<Integer> set = new HashSet<>(a);
        // Convert back to ArrayList
        ArrayList<Integer> result = new ArrayList<>(set);
        // Sort in descending order
        Collections.sort(result, Collections.reverseOrder());
        return result;
    }
}

这个函数使用了 HashSet 来去除重复的数字，然后将结果转换回 ArrayList，最后使用 `Collections.sort()` 方法对数组进行排序。因为要按照降序排序，所以传递了 `Collections.reverseOrder()` 参数。