有一个没有重复的集合 是，求S的所有子集，按生序排序，不能重复，用java

在Java中，你可以使用递归和HashSet来生成并存储所有非重复的子集。这里是一个简单的示例：

import java.util.*;

public class Subsets {
    private Set<List<Integer>> subsets;

    public Subsets(int[] nums) {
        this.subsets = new HashSet<>();
        generateSubsets(nums, new ArrayList<>(), 0);
    }

    private void generateSubsets(int[] nums, List<Integer> currentSet, int index) {
        // Base case: when the index reaches the length of array, add current set to result
        if (index == nums.length) {
            subsets.add(new ArrayList<>(currentSet));
            return;
        }
        
        // Include the element at the current index
        currentSet.add(nums[index]);
        generateSubsets(nums, currentSet, index + 1);

        // Exclude the element and move forward
        currentSet.remove(currentSet.size() - 1);
        generateSubsets(nums, currentSet, index + 1);
    }

    public List<List<Integer>> getSortedSubsets() {
        List<List<Integer>> sortedSubsets = new ArrayList<>(subsets);
        Collections.sort(sortedSubsets, Comparator.comparingInt(List::size)); // Sort by set size first, then lexicographically
        return sortedSubsets;
    }

    public static void main(String[] args) {
        int[] nums = {1, 2, 3};
        Subsets subsetGenerator = new Subsets(nums);
        System.out.println(subsetGenerator.getSortedSubsets());
    }
}

这个程序首先创建了一个空的HashSet来收集所有子集。然后通过递归地包含或排除数组中的元素，生成所有的子集。最后，将子集列表按照大小和元素升序排序。