Accesssing櫃檯外，同時循環的Java

Question

讓我得到的錯誤是0

I'ts師由於totDrivers值。我不確定是否因爲計數器沒有更新，因爲while循環循環。或者，如果這是因爲totDrivers我不正確地從循環外部訪問變量。

我讀過的其他帖子說，要訪問一個循環外的變量，你需要在循環之外初始化它。但它沒有說明如果通過這樣做，計數器更新值將出來。

[Exception in thread "main" java.lang.ArithmeticException:/by zero 
at Statistics.main(Statistics.java:84)] 

---

import java.util.Scanner; 

public class Statistics 
{ 

    public static void main (String [] args) 
    { 

     Scanner in=new Scanner(System.in); 

     //counters initilization 
     int f=0; //female 
     int m=0;//male 
     int u=0;//unspecified 
     int u25=0;//less than 25 in age 
     int mu=0;//male and under 25 
     int bt=0;//between 25 and 75 
     int ab=0;//above 75 
     int y=0;//res 
     int n=0;//non res 

     int age=0; 
     String gender="U"; 
     String nlRes="Y"; 
     int totDrivers=0; 

     while (age !=0) 
     { 

      totDrivers++; 
      System.out.print("Please enter age\\(Enter 0 if theres no more input\\): "); 
      age= in.nextInt(); 
      System.out.print("Please enter gender(M,F,or U): "); 
      gender= in.next(); 
      System.out.print("Please enter gender: "); 
      nlRes= in.next();  


      if (age<25) 
      { 
       u25++; 
      } 
      if(gender.equals("M")) 
      { 
       mu++; 
      } 
      else if(age>=25&&age<=75) 
      { 
       bt++; 
      } 
      else if(age>75) 
      { 
       ab++; 
      } 


      if(gender.equals("M")) 
      { 
       m++; 
      } 
      else if(gender.equals("F")) 
      { 
       f++; 
      } 
      else if(gender.equals("U")) 
      { 
       u++; 
      } 


      if(nlRes.equals("Y")) 
      { 
       y++; 
      } 
      else if(nlRes.equals("N")) 
      { 
       n++; 
      } 
      System.out.println("totd"+totDrivers); 
     } 
     //output 

     double perU25=(u25/totDrivers)*100; 
     double perMU25=(mu/m)*100; 
     double perF=(f/totDrivers)*100; 
     double perNonNL=(n/totDrivers)*100; 
     double perAbove=(ab/totDrivers)*100; 

     System.out.println("The % of drivers under 25 is : %"+perU25); 
     System.out.println("The % of male drivers under 25 is : %"+perMU25); 
     System.out.println("The % of female drives is : %"+perF); 
     System.out.println("The % of out of province drivers is : %"+perNonNL); 
     System.out.println("The % of drivers over the age of 75 is : %"+perAbove); 
    } 
} 

Answer 1

只是檢查，如果你的計數器= 0你做你的分裂之前

if(m != 0) 
{ 
double perMU25=(mu/m)*100; 
}