How can i make it so that if user inputs 0 a output line says that you cannot divide by zero in java

Question

I'm trying to not have the user input be 0 for "a" since this would cause the equation to divide by zero, which outputs an error, i would to be able to have a println saying that you cannot divide by zero if the user inputs 0 for "a" Here is my code, I'm not sure what I'm doing wrong, I'm still new at this, just need help:

import java.util.Scanner;

class a3main{

    public static void main(String[] args){

    Scanner keyboard = new Scanner(System.in);

    System.out.println("Enter the value of a");
    int a = keyboard.nextInt();

    System.out.println("Enter the value of b");
    int b = keyboard.nextInt();

    System.out.println("Enter the value of c");
    int c = keyboard.nextInt();

    double R1, R2, dis;

    dis = b * b - 4 * a * c; // This is the discriminant formula

    if(dis > 0 )
    {
        System.out.println("The roots are both real numbers and unequal");
        R1 = (-b + Math.sqrt(dis))/(2*a);

        System.out.println("The first root is: " + R1);

        R2 = (-b - Math.sqrt(dis))/(2*a);

        System.out.println("The second root is: " + R2);
        }
        else if(dis == 0)
        {   
         System.out.println("The roots are both equal and are equal");
         R1 = (-b + Math.sqrt(dis))/(2*a);
         System.out.println("The root is: " + R1);
                }    
         else if (a == 0)
    {
         System.out.println("You cannot divide by 0");
    }   
             else 
             {
       System.out.println("The roots are imaginary");
                     }
    }
}

Answer 1

You need to put your if(a == 0) check before your checks that look at dis.