Java：求開根號，向下取整，將double轉化爲int型

package classifier;

public class getSqrt {
    public static void main(String[] args){
        double a = 15;
        System.out.println(Math.sqrt(a));
        System.out.println(Math.floor(Math.sqrt(a)));
        double b = Math.floor(Math.sqrt(a));
        int i = (new Double(4.30)).intValue();
        System.out.println(i);
    }
}

向上取整用ceil