JAVA递归的理解

package Test;

public class TestRecursion {

	public static void main(String[] args) {
		long d1 = System.currentTimeMillis();
		System.out.printf("%d阶乘的结果：%s%n", 10, factorial(10));
		long d2 = System.currentTimeMillis();
		System.out.printf("递归费时：%s%n", d2-d1);
		
		factorialloop(10);
				

	}
	static long factorial(int n){
		if(n == 1){
			return 1;
		}else{
			return n * factorial(n-1);//n! = n*(n-1)!
		}
	}
	static long factorialloop(int a){
		long d3 = System.currentTimeMillis();
		long result = 1;
		while(a > 1){
			result*=a*(a-1);
			a-=2;			
		}
		long d4 = System.currentTimeMillis();
		System.out.println(result);
		System.out.printf("普通循环费时： %s%n", d4-d3);
		return result;
	}
}

比较发现迭代的花费时间少