Question

所以我对Java非常陌生，就在几个小时前刚刚开始。我不知道该怎么做;到目前为止我的代码：

import java.util.Scanner;
public class Class_one{
static Scanner userInput = new Scanner(System.in);
public static void main(String[] args){
    int[] listArray;
    System.out.print("Please enter the number to calculate the factorial for: ");
    if (userInput.hasNextInt()){
        int numEnter = userInput.nextInt();
        final int numEnterC = numEnter;
        if (numEnter >= 0){
            listArray = new int[numEnterC];
            int arrayVal = 0;
            while (numEnter >= 0){
                listArray [arrayVal] = numEnter;
                arrayVal++;
                numEnter = numEnter - 1;
                if (numEnter == 0){
                    break;
                }
            }
            while (arrayVal >= -1){
                int newArVal = listArray[arrayVal]*listArray[arrayVal - 1];
                newArVal = listArray[arrayVal];
                arrayVal = arrayVal - 1;
            }
            //I don't know what's happening in the next line:
            String nArVals = Integer.toString(newArVal));
            System.out.println(nArVals + " is the result of the factorial operations of " + numEnterC);
        }
        if (numEnter == 0){
            System.out.println("1");
        }
        if (numEnter <= 0){
            System.out.println("Negatives unavailable for factorial.");
        }
    }
}
}

那么我做错了什么？我不希望你们只是粘贴答案，我想自己弄清楚，所以你能给我一个提示，或者不是直接回答让我自己解决这个问题吗？

这是我收到的错误消息（我正在使用Eclipse）：

Exception in thread "main" java.lang.Error: Unresolved compilation problems:
newArVal cannot be resolved to a variable.
Syntax error on token ")", delete this token.
at project_one.Class_one.main(Class_one.java:27)

Answer 1

您无需创建数组

int numEnter = userInput.nextInt();
int factorial = 1;
for (int i=1; i <= numEnter; i++) factorial *= i;

Answer 2

这是一个框架不好的问题。

我会以递归方式完全不同地实现

public int factorial(int number){
    if(number>0){
        return number*factorial(number-1);
    } else {
    return 1;
    }
}

我还没有这样做。

Answer 3

变量newArVals在以下行中引用时不在范围内。

        String newArVals = Integer.toString(newArVal));

要使它在范围内，你必须在while循环之外定义newArVal，即

     int newArVal =0; 
     while (arrayVal >= -1){
            newArVal = listArray[arrayVal]*listArray[arrayVal - 1];
            newArVal = listArray[arrayVal];
            arrayVal = arrayVal - 1;
        }

我的java代码计算阶乘有什么问题？

3 个答案: