素数判断 Java

class Test{
	public static void main(String[] args) {
		boolean b=is_prime(13);
	}

	private static boolean is_prime(int i) {
		// TODO Auto-generated method stub
		if(i<=1)
			return false;
		int m = (int)(Math.sqrt(i)+0.5);
		for (int j = 2; j <=m; j++) {
			if(i%j == 0)
				return false;
		}
		
		return true;
	}


}