Java Display the Prime Factorization of a number

Question

So for my assignment, I have to write a program that asks the user for an integer input and then print out that number\'s prime factorization. This is what I have:

Answer 1

For one thing, your continue is inside the while loop, where it has no effect whatsoever. The minimal fix would be

public class PrimeFactor {
    public static void main(String[] args) {
        System.out.print("Enter a positive number: ");
        Scanner scanner = new Scanner (System.in);
        int number = scanner.nextInt();
        int count;
        for (int i = 2; i<=(number); i++) {
            count = 0;
            while (number % i == 0) {
                number /= i;
                count++;
            }
            if (count == 0) {
                 continue;
            }
            System.out.println(i+ "**" + count);
        }
    }
}

But you have some other problems:

• Your code is not properly "factored" (ironically, "factored" in this context means that is is not broken up into functions
• The variable names are poorly chosen
• You use a goto (continue in this case) when an if would suffice

Better code would be

public class PrimeFactor {
    public static void main(String[] args) {
        System.out.print("Enter a positive number: ");
        Scanner scanner = new Scanner (System.in);
        printFactors(scanner.nextInt());
    }
    public static void printFactors(int product) {
        for (int factor = 2; factor <= product; factor++) {
            int exponent = 0;
            while (product % factor == 0) {
                product /= factor;
                exponent++;
            }
            if (exponent > 0) {
                System.out.println(factor+ "**" + exponent);
            }
        }
    }
}