Question

Write Java code that allows a user to repeatedly enter numbers. Each time the user enters a number, the program should print out the average of the last 3 numbers (or all numbers if 3 or less have been entered). I would like a detailed explanation so that a beginner level Java programmer could understand.

Answer 1

code:

import java.util.Scanner;

class Main {

public static void main(String[] args) {

//declare a scanner variable to take user input

Scanner sc = new Scanner(System.in);

int a=0,b=0,c=0,sum=0,count=0;

double avg;

//take user input untill -1 entered

/*

repeatedly ask for 3 numbers in a loop, and exit if any input is -1;

and subtract the last entered number in next loop and get next number and find average

*/

while (true){

//let's say we have taken a, b, c => 3 inputs,

//sum variable will be , sum = a+b+c, avg = sum /3;

//while repeats again, now we take 4th input, let's say it as a2,

//now, we need to subtract a from sum and add a2 to it ,

// sum = sum -a, sum = sum+a2, which means sum(b+c+a2), and find new average

sum -= a;

System.out.println("Enter number (-1 to exit): ");

a = sc.nextInt();

if(a == -1) break;

sum += a;

if(count < 3)

avg = (double)sum/1;

else

avg = (double)sum/3;

System.out.printf("Average : %.2f\n",avg);

sum -= b;

System.out.println("Enter number (-1 to exit): ");

b = sc.nextInt();

if(b == -1) break;

sum += b;

if(count < 3)

avg = (double)sum/2;

else

avg = (double)sum/3;

System.out.printf("Average : %.2f\n",avg);

sum -= c;

System.out.println("Enter number (-1 to exit): ");

c = sc.nextInt();

if(c == -1) break;

sum += c;

avg = (double)sum/3;

System.out.printf("Average : %.2f\n",avg);

count += 3;

}

}

}