在java中使用可调用接口查找阶乘

Question

package projsamples;

import java.util.Collection;
import java.util.List;
import java.util.Scanner;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

public class FactorialUsingThreads {

    public static void main(String[] args)  throws InterruptedException,ExecutionException{

        Scanner reader = new Scanner(System.in);
        int number = reader.nextInt();
        ExecutorService es = Executors.newSingleThreadExecutor();
        Future<Integer> result=es.submit(new FactorialCalc(number));
        System.out.println("result value after calc is: "+ result);
        int finalResult =(int)result.get();
        System.out.println("The result of the factorial calculation for the"+number+"is: "+finalResult);
    }

    }

    class FactorialCalc implements Callable<Integer>{

    private int number;

    public FactorialCalc(int number) {
        super();
        this.number = number;
    }

    @Override
    public Integer call() throws Exception {
        // TODO Auto-generated method stub
        return factorial(number);
    }

    private Integer factorial(int number2) throws InterruptedException  {
        // TODO Auto-generated method stub
        int number = number2;
        int result = 1;
        while(number2 !=0){

            result = number*result;
            number=number-1;
            Thread.sleep(100);

        }
        System.out.println("result"+result);
        return result;

    }
}

在上面的代码中，我想要做的是，我想找到用户输入的任何数字的阶乘数。 返回的结果是当我尝试对整数对象进行类型转换时的对象，并且没有发生获取值。 我知道这可能是我无法做到的非常基本的事情。对此的任何小提示都会有所帮助。

非常感谢所有可以提供帮助的好心人。

Answer 1

这与多线程有关。 您只需要在factorial方法中使用number2 ，并记住将其递减。

private Integer factorial(int number2) throws InterruptedException  {    
    int result = 1;
    while(number2 != 0){    
        result = number2 * result;
        number2 = number2 - 1;
        Thread.sleep(100);    
    }
    System.out.println("result"+result);
    return result;    
}