단정

public class Exerciseh9_9 {
	public static int factorial(int n) {
		int fact = 1;
		if (n < 1) {
			System.out.println("n must be one or more.");
			System.exit(1);
		}
		for (int i=1; i<=n; ++i)
			fact *= i;
		return fact;
	}
	public static void main(String[] args) {
		System.out.println("3 factorial = " + factorial(3));
	}
}

 

# 단정 사용

public class Exercise9_9{
	static void factorial(int n) {
		int fact = 1;
		assert (n >= 1) : n + " n must be one or more.";
		for (int i=1; i<=n; ++i)
			fact *= i;
		System.out.println(n + " factorial = " + fact);
	}
	public static void main(String[] args) {
		factorial(3);
		factorial(0);
	}
}