1、小数取整

public class Test{
    public static void main(String args[]){
        double d = 100.675;
        float f = -90;    
        System.out.println(Math.ceil(d));
        System.out.println(Math.ceil(f)); 
        System.out.println(Math.floor(d));
        System.out.println(Math.floor(f)); 
    }
}
// 输出
101.0
-90.0
100.0
-90.0

Math.ceil 向上取整
Math.floor 向下取整