Number Averager

[Kid Programmer]

Hello guys. I am rather new to Java and so I decided to test my knowledge and write a simple number averaging program. When I compile it though I get the following errors:

NumberAverager. java:14: cannot find symbol
symbol : variable n1
location: class NumberAverager
int area = (n1 + n2 + n3) / 3;
^
NumberAverager. java:14: cannot find symbol
symbol : variable n2
location: class NumberAverager
int area = (n1 + n2 + n3) / 3;
^
NumberAverager. java:14: cannot find symbol
symbol : variable n3
location: class NumberAverager
int area = (n1 + n2 + n3) / 3;
^
NumberAverager. java:14: operator / cannot be applied to java.lang.Strin g,int
int area = (n1 + n2 + n3) / 3;
^
4 errors

Here is my source code. I tried to add a lot of comments.

/* Number Averaging Program
Written by Kid Programmer */
import java.util.Scanner;

class NumberAverager {                                          //define the class
	public static void main(String[] args) {		//make the main function	
		Scanner scan = new Scanner (System.in);		//create a scanner
		System.out.println("This program will average 3 numbers.");	//explain the program
		System.out.println("Please enter the three numbers: ");		//ask the user to enter the numbers
		while ( scan.hasNextInt() ) {			
			int n1 = scan.nextInt();			//prompt the user for the first number
			int n2 = scan.nextInt();			//prompt the user for the second number
			int n3 = scan.nextInt();			//prompt the user for the third number
		}
		int area = (n1 + n2 + n3) / 3;				//calculate the area
		System.out.println("The area is: " +area);		//print out the area
	}
}

[tomshorts07]

you didnt declare the variable correctly

all of those errors- (the ones that say cannot find symbol) are caused because you are supposed to use a 'double' variable type

rather than declare it as

int area = (n1 + n2 + n3) / 3;        //calculate the area

reformat it to be

double area = (n1 + n2 + n3) / 3;        //calculate the area

and it should work fine!

[Kid Programmer]

you didnt declare the variable correctly

all of those errors- (the ones that say cannot find symbol) are caused because you are supposed to use a 'double' variable type

rather than declare it as

int area = (n1 + n2 + n3) / 3;        //calculate the area

reformat it to be

double area = (n1 + n2 + n3) / 3;        //calculate the area

and it should work fine!

I tried changing my code to:

/* Number Averaging Program
Written by Kid Programmer */
import java.util.Scanner;

class NumberAverager {                                          //define the class
	public static void main(String[] args) {		//make the main function	
		Scanner scan = new Scanner (System.in);		//create a scanner
		System.out.println("This program will average 3 numbers.");	//explain the program
		System.out.println("Please enter the three numbers: ");		//ask the user to enter the numbers
		while ( scan.hasNextInt() ) {			
			double n1 = scan.nextInt();			//prompt the user for the first number
			double n2 = scan.nextInt();			//prompt the user for the second number
			double n3 = scan.nextInt();			//prompt the user for the third number
		}
		double area = (n1 + n2 + n3) / 3;        //calculate the area
		System.out.println("The area is: " +area);		//print out the area
	}
}

yet I still get the errors:

NumberAverager. java:15: cannot find symbol
symbol : variable n1
location: class NumberAverager
double area = (n1 + n2 + n3) / 3; //calculate the area
^
NumberAverager. java:15: cannot find symbol
symbol : variable n2
location: class NumberAverager
double area = (n1 + n2 + n3) / 3; //calculate the area
^
NumberAverager. java:15: cannot find symbol
symbol : variable n3
location: class NumberAverager
double area = (n1 + n2 + n3) / 3; //calculate the area
^
NumberAverager. java:15: operator / cannot be applied to java.lang.Strin g,int
double area = (n1 + n2 + n3) / 3; //calculate the area
^
4 errors

[tomshorts07]

alrighty, i figured it out kidprogrammer!

you have to define the variables in the beginning of the program

  Scanner scan = new Scanner (System.in);  //create a scanner
         double area;
         double n1=0;
         double n2=0;
         double n3=0;
         System.out.println("This program will average 3 numbers."); //explain the program
         System.out.println("Please enter the three numbers: ");  //ask the user to enter the numbers

then just take out the 'double' declarations in the remainder of the program


also, i noticed that your while () loop will not end-

if you want to utilize the while loop, make a 'counting variable' to count up to end the loop

 int i = 0;
         while (i < 3) {         
            n1 = scan.nextInt();   //prompt the user for the first number
            n2 = scan.nextInt();   //prompt the user for the second number
            n3 = scan.nextInt();   //prompt the user for the third number
i++; //increases the value of the count by 1
         }

[JosAH]

You defined your variables n1, n2 and n3 (no matter their type) in the body of the
while loop; this means that they don't exist outside of that while loop body; your
compiler rightly complains about it so define them somewhere else where they
are visible when you need them.

kind regards,

Jos

[Kid Programmer]

Thank you. I got the program to work with this source:

/* Number Averaging Program
Written by Kid Programmer */
import java.util.Scanner;

class NumberAverager {                                          //define the class
	public static void main(String[] args) {		//make the main function	
      	       Scanner scan = new Scanner (System.in);  //create a scanner
               double area;
               double n1=0;
               double n2=0;
               double n3=0;
               System.out.println("This program will average 3 numbers."); //explain the program
               System.out.println("Please enter the three numbers: ");  //ask the user to enter the numbers
      	       int i = 0;
               while (i < 3) {         
                  n1 = scan.nextInt();   //prompt the user for the first number
                  n2 = scan.nextInt();   //prompt the user for the second number
                  n3 = scan.nextInt();   //prompt the user for the third number
		  area = (n1 + n2 + n3) / 3;
		  System.out.println("The area is: " +area);
    		  i++;			 //increases the value of the count by 1

		}
	}		
}

But one thing. I get an error whenever you type characters while being prompted for the numbers. Is there a way to stop this?

[JosAH]

But one thing. I get an error whenever you type characters while being prompted for the numbers. Is there a way to stop this?

Yes there is; read the API documentation for the Scanner class; it has methods
that test whether or not you can read an int from the stream.

kind regards,

Jos