This is my first calculator in Java. I just started learning a week ago so any feedback (positive and negative) is welcome. Tell me what's good and what I can improve on.
import java.util.Scanner;
public class Calculator {
public static void main(String[] args) {
// Creates scanner object
Scanner scanner = new Scanner(System.in);
// Controls the start and stop of the program
boolean run = true;
// Sets and resets the operand and answer variables
int fnum = 0;
int snum = 0;
int answer = 0;
// While loop that keeps the program running until user exits
while (run) {
// Calculator interface
System.out.println("=====================================");
System.out.println(" Calculator V1.0 ");
System.out.println("=====================================");
System.out.println("1. Addition");
System.out.println("2. Subtraction");
System.out.println("3. Multiplication");
System.out.println("4. Division");
System.out.println("5. Exit");
System.out.printf("Please pick an operation(1-5): ");
// Prompts user to choose an operation
int operation = scanner.nextInt();
// Does stuff depending on what integer the user enters
switch (operation) {
case 1:
System.out.printf("Enter first number: ");
fnum = scanner.nextInt();
System.out.printf("Enter second number: ");
snum = scanner.nextInt();
answer = fnum + snum;
System.out.println("The answer is: " + answer);
break;
case 2:
System.out.printf("Enter first number: ");
fnum = scanner.nextInt();
System.out.printf("Enter second number: ");
snum = scanner.nextInt();
answer = fnum - snum;
System.out.println("The answer is: " + answer);
break;
case 3:
System.out.printf("Enter first number: ");
fnum= scanner.nextInt();
System.out.printf("Enter second number: ");
snum = scanner.nextInt();
answer = fnum * snum;
System.out.println("The answer is: " + answer);
break;
case 4:
System.out.printf("Enter first number: ");
fnum = scanner.nextInt();
System.out.printf("Enter second number: ");
snum = scanner.nextInt();
answer = fnum / snum;
System.out.println("The answer is: " + answer);
break;
case 5:
System.out.println("Thank you for using the calculator!");
scanner.close();
run = false;
break;
default:
System.out.println("Invalid operation!");
break;
}
}
}
}