Question

I'm working in Java and am working on a project where I need to find an average. The catch is that for some of the values there is no data because they will be entered at a later date. I have variables assigned so that for each entry if there is an input I'll have it say _____available = 1, otherwise the variable will equal 0. I'll use an example to make this more clear. Let's say I am trying to find the average time of a car in a race. The car is set to run 5 races. He has run races 1, 3, and 5 but not 2 or 5. Or maybe he has run all 5. It would change depending on the user's input. How can I write an equation in Java that will find the average, no matter how many races the racer has run? I was thinking I would use an if statement, maybe a series of them that say if race1Available = 1 then add the time for race 1 to total time, if not don't add it. And I would need to do that for all 5 races. I would also need to do that for the total number of races so that if I only run 3 races, then I would divide the total time by 3.

Answer 1

Update: pls see new code added at bottom. carAvg2.java

We don't need to have two separate variables to keep track of
availability and time

we can only store Time, if its 0 means not available
as follows

Thanks

//------- carAvg.java
import java.util.Scanner;

public class carAvg {
        
        public static void main (String args[]) {
                
                int count = 0;
                double total = 0;
                double[] times = {0,0,0, 0,0};
                
                Scanner sc = new Scanner(System.in); //to read input
                System.out.println("Enter race time, otherwise enter 0 if race NOT run");
                
                for (int i = 0; i < times.length ; i++)
                {
                        System.out.print("enter Race " + (i+1) + ": ");
                        times[i] = sc.nextDouble();
                        
                        if (times[i] > 0)
                        {
                                //increase count if race time entered
                                count++;
                                
                                //also add time to the total
                                total = total + times[i];
                        }                                                                       
                }
                System.out.println("Average time for "  + count + " races= " + (total/count));          
                
                //Use following to display only 2 decimal places like 35.41 instead of 35.41456789
                //String strAvg = String.format("%.2f", total/count);           
                //System.out.println("Average time for "  + count + " races= " + strAvg);               
        }
}

//------- end of carAvg.java

Output

Added following code to Ask before entering race time

//------- carAvg2.java
import java.util.Scanner;

public class carAvg2 {
        
        public static void main (String args[]) {
                
                int count = 0;
                double total = 0;
                double[] times = {0,0,0, 0,0};
                
                Scanner sc = new Scanner(System.in); //to read input
                                
askNext:for (int i = 0; i < times.length ; i++)
                {
                        do {
                                System.out.print("Do you want to run Race" + (i+1) + "? y/n: ");
                                String ch = sc.next();
                                if ( ch.equals("n") )
                                {
                                        continue askNext;       // askNext is label of for loop 
                                }
                                else if ( ch.equals("y") )
                                {
                                        break;  //valid input so ask for time 
                                }                                                               
                        } while(true);
                        
                        do{
                                System.out.print("Enter time for Race" + (i+1) + ": ");
                                times[i] = sc.nextDouble();
                                
                                if (times[i] >= 0)
                                {
                                        //increase count if race time entered
                                        count++;
                                        
                                        //also add time to the total
                                        total = total + times[i];
                                }                                               
                        } while( times[i]<0 ); //repeat if -ve value entered
                }
                System.out.println("Average time for "  + count + " races= " + (total/count));          
                
                //Use following to display only 2 decimal places like 35.41 instead of 35.41456789
                //String strAvg = String.format("%.2f", total/count);           
                //System.out.println("Average time for "  + count + " races= " + strAvg);               
        }
}

//------- end of carAvg2.java

new output