想不通为什么程序将无法正常运行

Question

我一直在试图让这个程序工作，应该继续从用户输入，直到输入-1并计算总和。 问题如下： 设计并实现一个Java程序（命名为 InputSum ），它提示用户输入一个正整数 。该程序应为ac cept整数，直到用户输入值-1 （负数）。用户输入-1后，程序 应显示输入的数字，然后显示其总和 ，如下所示。请注意，-1不是输出的一部分。 确保程序 在proc 之前验证每个输入的号码，因为用户可以输入除句号值-1 以外的负数 数字。
设计你的程序，使其 允许用户重新运行 程序与上面显示的同一运行中的一组不同的输入。 记录您的代码，并按上图所示组织空间输出。

这里是我的代码：

/* Class:  CS1301 
* Section:  9:30 
* Term:   Fall 2015 
* Name:   Matthew Woolridge 
* Instructor: Mr. Robert Thorsen 
* Assignment: Assignment 6 
* Program:  1 
* ProgramName: InputSum 
* Purpose:  The program prompts the user to input numbers until -1 is entered and calculates the sum 
* Operation:  The information is statically instantiated in the code and 
*    the data is output to the screen. 
* Input(s):  The input is the numbers 
* Output(s):  The output will be the sum of the numbers 
* Methodology: The program will use loops to determine if numbers or still to be entered or if -1 was entered 
* 
*/ 

import java.util.*; 
import java.io.*; 
public class InputSum 
{ 

    public static void main (String[] args) 
    { 

     /****************************************************************************** 
     *       Declarations Section        * 
     ******************************************************************************/ 
     /****************************CONSTANTS********************************/ 
     Scanner scan = new Scanner(System.in); //Initializes scanner 

     int n = 1; 
     int [] num = new int[n]; //Creates array for input numbers 
     int i; 
     int sum=0; 

     /****************************************************************************** 
     *        Inputs Section         * 
     ******************************************************************************/ 

     System.out.print("Please input integers, note that -1 ends the submissions: "); //Prompts the user for input 

    /****************************variables********************************/ 
    //***************************Calculations in processing************************// 
    /****************************************************************************** 
     *        Processing Section       * 
     ******************************************************************************/ 
     for(i=0; i<num.length; i++) 
     { 
     num[i] = scan.nextInt(); //Continues to read numbers and add them to the sum 
     n = n + 1; //Adds to the array maximum 
     sum = sum + num[i]; //Calculates the sum 
     if (num[i] == -1){ 
      break; 
     } 
     } 
     System.out.print("The numbers entered are: " + num[i]); 
     System.out.print("\nThe sum of the numbers is: " + sum); 

     /****************************************************************************** 
     *        Outputs Section        * 
     ******************************************************************************/ 
     //***************Output is in the processing**************************// 
    } 
} 

的问题是，该方案不断得到在哪里它应该打印之行挂断了电话。任何和所有的帮助表示赞赏！

Answer 1

您可以使用List来存储数字和一个无限循环以保持接收来自用户的输入。你也应该在开始处理数字之前检查停止条件（因为你的问题提到-1不是输出的一部分）。这里是一个例子

import java.util.*; 
import java.io.*; 
public class InputSum 
{ 

    public static void main (String[] args) 
    { 

     /****************************************************************************** 
     *       Declarations Section        * 
     ******************************************************************************/ 
     /****************************CONSTANTS********************************/ 
     Scanner scan = new Scanner(System.in); //Initializes scanner 
     int number; //Declare a variable that will hold the temporal value that is read on the input stream  
     int sum=0; 

     // Use a List 
     List<Integer> numbers = new ArrayList<Integer>(); 

     /****************************************************************************** 
     *        Inputs Section         * 
     ******************************************************************************/ 

     System.out.print("Please input integers, note that -1 ends the submissions: "); //Prompts the user for input 

    /****************************variables********************************/ 
    //***************************Calculations in processing************************// 
    /****************************************************************************** 
     *        Processing Section       * 
     ******************************************************************************/ 
     // use an infinite loop 
     for(; ;) 
     { 


     // You should normally do this check when you enter the loop 
     // so that -1 which is a stop token should not be added to the list 
     // and not taken into account in the sum 


     number = scan.nextInt(); //Continues to read numbers and add them to the sum 
     if (number == -1){ 
       break; 
     } 

     // You could write numbers.add(number) which would be 
     // Java's autoboxing feature, but this is what would really take place 
     numbers.add(Integer.valueOf(number)); 
     sum += number; //Calculates the sum 


     } 
     System.out.print("The numbers entered are: " + numbers); 
     System.out.print("\nThe sum of the numbers is: " + sum); 

     /****************************************************************************** 
     *        Outputs Section        * 
     ******************************************************************************/ 
     //***************Output is in the processing**************************// 
    } 
} 

Answer 2

而不是使用数组（因为它限制了您的输入数量），您可以使用一个临时变量来计算总和的值。如下图所示：

int sum=0; 
int num=0; 
while(num != -1) { 
    sum = sum + num; 
    num = scan.nextInt(); //note that the variables can be reused 
}