试图在 Java 中的扫描仪用户输入中找到最小数量

Question

I'm coding a test averager in Java. I have to use do while, while, if loops.

I have the user inputting test scores, asking for a negative number to leave the while loop.

I have to display the number of scores entered, the highest, the lowest, and the average.

However, I am having problems displaying the lowest number as it as popping up as 0.

For input of 95, 93, 92, 91, and -1:

The number of scores entered: 4 The Highest: 95 The Lowest: 0 The average is: 92

My code:

import java.util.*;

public class Lab7 
{

    public static void main(String[] args) 
    {
        System.out.println("This program computes the average of");
        System.out.println("a list of (nonnegative) exam scores.");
        int sum;
        int numberOfTests;
        int testInput;
        String answer;
        int minimum = 0;
        int maximum = 0;
        Scanner keyboard = new Scanner (System.in);
        
        do
        {
            System.out.println();
            System.out.println("Enter all the scores to be averaged.");
            System.out.println("Enter a negative number after");
            System.out.println("you have entered all the scores.");
            sum = 0;
            numberOfTests = 0;
            testInput = keyboard.nextInt();

            while (testInput >= 0)
            {
                sum = sum + testInput; 
                numberOfTests++;
                

                 if (testInput < minimum)
                {
                    minimum = testInput;
                }
                
                if (testInput > maximum) 
                {
                    maximum = testInput;
                }
    
                testInput = keyboard.nextInt();
            }

            if (numberOfTests > 0) 
            {
                System.out.println("The number of scores entered: " + numberOfTests);
                System.out.println("The Highest: " + maximum);
                System.out.println("The Lowest: " + minimum);
                System.out.println("The average is: " +
                (sum / numberOfTests));    

            }

            else 
            {
                System.out.println("No scores to average.");
            }

            System.out.println("Want to average another exam?");
            System.out.println("Enter yes or no.");
            answer = keyboard.next();
        }
        
        while (answer.equalsIgnoreCase("yes"));
    }

    
}

Answer 1

You initialise minimum with 0 , so for positive inputs it will always be the smallest value. That means if (testInput < minimum) will always be false . To fix this, initialise it with Integer.MAX_VALUE instead.

In general, it is a good idea to start a maximum value with the lowest possible value , like Integer.MIN_VALUE or Double.MIN_VALUE or in your case with 0 , since there are no negative scores. Furthermore, the minimum should be initialised with the largest possible value , like described above.

That way, your checks will always work as intended.

Answer 2

This is due to this line int minimum = 0; as your input scores are greater than 0 thus your this condition will never be satisfied if (testInput < minimum) and the value of minimum won't never-ever changes and will remain as 0 . Hence define it as minimum = Integer.MAX_VALUE

Following is your code in a working state and I also made some optimizations which will help you in a better way of writing code:

public class Solution{
    public static void main(String[] args) 
    {
        int sum = 0, numberOfTests = 0, testInput , minimum = Integer.MAX_VALUE , maximum = Integer.MIN_VALUE;
       
        System.out.println("This program computes the average of \na list of (nonnegative) exam scores. \n");
        
        Scanner keyboard = new Scanner (System.in);
        
        do
        {
            System.out.println();
            System.out.println("Enter all the scores to be averaged.");
            System.out.println("Enter a negative number after \nYou have entered all the scores.");
            
            testInput = keyboard.nextInt();

            while (testInput >= 0){
                sum += testInput; 
            
                numberOfTests++;                

                if (testInput < minimum) minimum = testInput;
                
                if (testInput > maximum) maximum = testInput;
                    
                testInput = keyboard.nextInt();
            }

            if (numberOfTests > 0) 
            {
                System.out.println("The number of scores entered: " + numberOfTests);
                System.out.println("The Highest: " + maximum);
                System.out.println("The Lowest: " + minimum);
                System.out.println("The average is: " +
                ((float)sum / numberOfTests));    
            }

            else 
                System.out.println("No scores to average.");
            

            System.out.println("Want to average another exam?");
            System.out.println("Enter yes or no.");

        }
        
        while (keyboard.nextLine().trim().equalsIgnoreCase("yes"));
        
        keyboard.close();
    }
    
}

Thanks