Java中怎么实现并行计算器

package test;import java.util.*;import java.util.concurrent.*;public class Main {    final static ExecutorService executorService = Executors.newCachedThreadPool();        public static void main(String [] args) throws ExecutionException, InterruptedException {
        Scanner scanner = new Scanner(System.in);        while (scanner.hasNext()) {
            System.out.println("请输入加法计算器和乘法计算器个数");            String inputStr =  scanner.nextLine();            String[] operateNumArry = scanner.nextLine().split(" ");            int plusNum = Integer.parseInt(operateNumArry[0]);            int mulNum = Integer.parseInt(operateNumArry[1]);            if (plusNum < 0 || mulNum < 0) {
                System.out.println("并行计算器数量要大于0");                break;            }
        
            LinkedList<Integer> plus_numbers = new LinkedList<>();            LinkedList<LinkedList<Integer>> mul_number_array = new LinkedList<>();            String [] inputArray = inputStr.split("\\+");                        for (int i = 0; i < inputArray.length; i++) {if (!inputArray[i].contains("*")) {
                    plus_numbers.add(Integer.parseInt(inputArray[i]));                } else {
                    LinkedList<Integer> mul_numbers = new LinkedList<>();                    String [] mul_numbers_str = inputArray[i].split("\\*");                    for (int j = 0; j < mul_numbers_str.length; j++) {
                        mul_numbers.add(Integer.parseInt(mul_numbers_str[j]));                    }//乘排序                    Collections.sort(mul_numbers);                    //添加到list                    mul_number_array.add(mul_numbers);                }
            }
            
            StringBuilder builder = new StringBuilder();            calculateSum(plus_numbers, mul_number_array, plusNum, mulNum,builder);            System.out.println(builder.toString());        }
    }    
    /**     * 計算     * @param plusNumbers     * @param mulNumbers     * @param plusNum     * @param mulNum     */    public static void calculateSum(LinkedList<Integer> plusNumbers, LinkedList<LinkedList<Integer>> mulNumbers, int plusNum, int mulNum, StringBuilder builder) throws ExecutionException, InterruptedException {//首先打印        printResult(plusNumbers, mulNumbers, builder);        if (plusNumbers.size() == 1) {return;        }       //計算加        int requiredPlusNum = plusNumbers.size();        if (requiredPlusNum > plusNum)
            requiredPlusNum = plusNum;        else if (requiredPlusNum <= plusNum)
            requiredPlusNum--;                for (int i = 0; i < requiredPlusNum; i++) {
            Integer first_plus_factor = plusNumbers.poll();            Integer second_plus_factor = plusNumbers.poll();            Future<Integer> future = executorService.submit(new Operator(first_plus_factor, second_plus_factor, 0));            plusNumbers.addLast(future.get());        }    //计算乘        int requiredMulNum = mulNumbers.size();        if (requiredMulNum > mulNum)
            requiredMulNum = mulNum;                for (int i = 0; i <  requiredMulNum; i++) {
    
            LinkedList<Integer> mulNumberArray = mulNumbers.poll();            Integer first_mul_factor = mulNumberArray.poll();            Integer second_mul_factor = mulNumberArray.poll();            Future<Integer> future = executorService.submit(new Operator(first_mul_factor, second_mul_factor, 2));                        if (mulNumberArray.isEmpty())
                plusNumbers.add(future.get());            else {
                mulNumberArray.offer(future.get());                mulNumbers.offer(mulNumberArray);            }
        }    //递归调用        calculateSum(plusNumbers, mulNumbers, plusNum, mulNum, builder);    }    static void printResult(final LinkedList<Integer> plusNumbers, final LinkedList<LinkedList<Integer>> mulNumbers, StringBuilder builder) {//加排序        Collections.sort(plusNumbers);        builder.append("{");        plusNumbers.forEach(item-> {builder.append(item).append("+");        });            if (!mulNumbers.isEmpty()) {//相同數量的乘因子按第一個不同的最小值排序            Collections.sort(mulNumbers, new CustomComparator());            mulNumbers.forEach(item->{
                item.forEach(i->{builder.append(i).append("*");                });                        builder.deleteCharAt(builder.lastIndexOf("*")).append("+");            });        }
        
        builder.deleteCharAt(builder.lastIndexOf("+")).append("}").append("\n");    }    static class CustomComparator implements Comparator<List<Integer>> {@Override        public int compare(List<Integer> o1, List<Integer> o2) {if (o1.size() == o2.size()) {for (int i = 0; i < o1.size(); i++) {if (o1.get(i) > o2.get(i))return 1;                    else if (o1.get(i) < o2.get(i))return -1;                    else                        return 0;                }            return 0;            } else if (o1.size() > o2.size()){return 1;            }        return -1;        }
    }    
    static class Operator implements Callable <Integer> {//第一因子        private int firstNumber;        //第二因子        private int secondNumber;        //操作類型：加、減、乘、除：0/1/2/3        private int type;            public Operator(int firstNumber, int secondNumber, int type) {this.secondNumber = secondNumber;            this.firstNumber = firstNumber;            this.type = type;        }    public Integer call() throws Exception {if (type == 0)return firstNumber + secondNumber;            if (type == 1)return firstNumber - secondNumber;            if (type == 2)return firstNumber * secondNumber;            if (type == 3)return firstNumber / secondNumber;            if (type == 4)return firstNumber % secondNumber;            return 0;        }
    }
}