如何解决这个简单的作用域错误？

Question

Having some issues with scoping. I am trying to write a program using a loop that takes 10 values representing exam grades (between 0 and 100) from the keyboard and outputs the minimum value, maximum value and average value of all the values entered. My program cannot accept values less than 0 or greater than 100.

import java.util.Scanner; 
import java.util.Arrays;

public class ExamBookClient
{
   public static void main( String[] args)
   {
       Scanner scan = new Scanner(System.in);

       int MAX = 100;
       int MIN = 0;
       int[] grades = new int[10];


       System.out.println("Please enter the grades into the gradebook.");
       if(scan.hasNextInt())
       {
         for (int i = 0; i < grades.length; i++)
          {
             if( x>MIN && x<MAX)
             {
             int x = scan.nextInt();
             grades[i] = x;
          }
       }
    }  
       System.out.print("The grades are " + grades.length);
   }
 } 

My compiler error is that I cannot fix the scoping error:

    ExamBookClient.java:21: error: cannot find symbol
             if( x>MIN && x<MAX)
                 ^
  symbol:   variable x
  location: class ExamBookClient
ExamBookClient.java:21: error: cannot find symbol
             if( x>MIN && x<MAX)
                          ^

Answer 1

To fix the scoping problem, move the declaration/initialization of x to a point before its first use:

int x = scan.nextInt();
if( x>MIN && x<MAX ) {
    grades[i] = x;
}

There are several problems with your code:

• if(scan.hasNextInt()) will be executed only before the first read of the int ; you should change your code to check for next int on each iteration of the loop
• You need to add variables for the current min , max , and total
• You do not need to store the values in the array, because the three scalars are enough to compute all three outputs required of your program.

Answer 2

Move x on top of the if.

if(scan.hasNextInt())
   {
     for (int i = 0; i < grades.length; i++)
      {
         int x = scan.nextInt();
         if( x>MIN && x<MAX)
         {

         grades[i] = x;
      }
   }

Answer 3

You have declared x inside the if clause. So when your program reaches the if , x won't be defined. Try this:

int x = scan.nextInt(); // OUTSIDE THE IF
if( x > MIN && x < MAX)
{        
    grades[i] = x;
}