笛卡尔积算法

/**
     * 生成笛卡尔积
     * @param dimvalue
     * @param result
     * @param layer
     * @param curList
     */
    private static void descartes(List<List<String>> dimvalue, List<List<String>> result, int layer, List<String> curList) {
        if (layer < dimvalue.size() - 1) {
            if (dimvalue.get(layer).size() == 0) {
                descartes(dimvalue, result, layer + 1, curList);
            } else {
                for (int i = 0; i < dimvalue.get(layer).size(); i++) {
                    List<String> list = new ArrayList<>(curList);
                    list.add(dimvalue.get(layer).get(i));
                    descartes(dimvalue, result, layer + 1, list);
                }
            }
        } else if (layer == dimvalue.size() - 1) {
            if (dimvalue.get(layer).size() == 0) {
                result.add(curList);
            } else {
                for (int i = 0; i < dimvalue.get(layer).size(); i++) {
                    List<String> list = new ArrayList<>(curList);
                    list.add(dimvalue.get(layer).get(i));
                    result.add(list);
                }
            }
        }
    }

    /**
     * 调用生成列表
     * @param list
     * @return
     */
    public static List<String> result(List<List<String>> list){
        List<List<String>> result = new ArrayList<>();
        descartes(list, result, 0, new ArrayList<>());
        //重组数据
        List<String> data=new ArrayList<>();
        result.forEach(oList->{
            StringBuilder sb=new StringBuilder();
            for(int i=0;i<oList.size();i++){
                sb.append(oList.get(i));
                if(i!=oList.size()-1){
                    sb.append(",");
                }
            }
            data.add(sb.toString());
        });
        return data;
    }