Looping Input Help

[Hank Harrison]

Hi all. Ok here is a bit of code I have so far.Im trying to write a program that has the user input a variety of grades. if the user enters a number not between 0 and 100 it gives an error message telling them to input a number between 0 and 100 and to keep continuing input numbers. When the user is finished I need the program to calculate the highest, lowest, and average grade of all the inputs.

My problem is i'm unsure of how to read each input from the scanner individually to be able to calculate these things. I've written other programs having a set number of variables, but i'm lost when it comes to a user generated amount of variables. any tips on how I would go about doing this? This is what I have so far. Thanks.

import java.util.Scanner;



public class lab5 {

	public static void main(String[] args) {
		
		
		System.out.print("Please input the total number of students:");
		
		
		Scanner input = new Scanner(System.in);
	
	
		int numstudents = input.nextInt();
	
		
		
		System.out.print("Please input the students' grade:");
		
		
		
		int sum = 0;
		int maxValue = Integer.MAX_VALUE;
		int minValue = Integer.MIN_VALUE;
		
		Scanner input2 = new Scanner(System.in);
		int grade = input2.nextInt();
		
		
		if(grade < 0)
			System.out.print("Grades must be between 0 and 100\nPlease input another score:");
		
		
		else if (grade > 0 && grade < 100){
			sum += grade;
			System.out.println("The highest grade is:" + grade);}
		}
}
	
		

[K. Tsang]

Well you surely need some kind of array of collection to store all the input grades. Then from this find the lowest, highest and average.

Also you maxValue and minValue can set to 100 and 0 respectively if you only allow inputs between 0 and 100.

Are you able to loop to get user inputs?

[Campbell Ritchie]

I suggest you create a utility class (search my posts for “utility class” and you should find some useful hints) and give it some methods

public class AyyarUtilities
{
   public static double average(int[] numbers)
   {
      average = ...
      return average;
   }

   public static int maxValue(int[] numbers)
   {
      ...
      return maxValue;
   }

   public static int minValue(int[] numbers)
   {
      ...
      return minValue;
   }
...
}

[Campbell Ritchie]

My, wasn't my spelling bad in the last post

[Hank Harrison]

Well I was thinking arrays as well when I first saw my assignment but the professor stated

"You do not need to use array to save each input score for this lab. A Single
loop to read in each grade, compare with the current highest grade, lowest grade, and
calculate the running sum at the same time."

so that threw me off. How would I go about using a loop to read each grade, and distinguishing between each grade in the scanner? So far the way I have it set up it only seems to be reading the first number. Any ideas? Thanks

[Hank Harrison]

Ok here is what I have now using arrays, I just need to figure out how to use loops instead as instructed. Any Ideas?

import java.util.*;
public class HighestScore

{
public static void main(String[] args)
{
int num =0;
Scanner in = new Scanner(System.in);
System.out.println("Please input the total number of students: ");
num = in.nextInt();
int[] grade_array = new int[num];
int sum =0;
System.out.println("Please input the students’ grade: ");
for(int i=0; i<num; i++)
{
grade_array[i] = in.nextInt();
if(grade_array[i]<0 || grade_array[i]>100)
{
System.out.println("Grade must between 0 and 100.");
System.out.println("Please input another score: ");
i--;
}
} // end for
int max = grade_array[0];
int min = grade_array[0];
sum = grade_array[0];
for(int i=1; i<num; i++)
{
if(grade_array[i]>max) max = grade_array[i];
if(grade_array[i]<min) min = grade_array[i];
sum = sum + grade_array[i];
}
System.out.println("The highest grade is: "+max);
System.out.println("The lowest grade is: "+min);
System.out.println("The average grade is: " + (double)(sum)/num);
} // end main
} // end class

[Tony Docherty]

Hank Harrison wrote:I just need to figure out how to use loops instead as instructed. Any Ideas?

What loop constructs do you know about and of those which one seems most suitable and why?

[Hank Harrison]

Well the "while" loop is what we have been covering in class so I'm assuming that's what the professor is mentioning to put into the code. I don't know how to apply that to each grade individually.

[Tony Docherty]

Ok, so look at the requirements and identify one place where you may need a loop and decide what determines if the loop should repeat. Then look at your code and find the lines of code that need to be wrapped in a loop. Finally add the while loop.
Now build and test your code and once you have it fully working go back to the requirements and repeat the process for the next loop.