Java Math-Random

Math

public class MathDemo {
    public static void main(String[] args) {
        double d = Math.ceil(16.34);//ceil返回大于指定数据的最小整数。
        double d1 = Math.floor(12.34);//floor返回小于指定数据的最大整数。

        long l = Math.round(12.54);//四舍五入
        sop("d="+d);
        sop("d1="+d1);
        sop("l="+l);

        double d2 = Math.pow(2,3);
        sop("d2="+d2);
    }
    public static void  sop(Object obj)
    {
        System.out.println(obj);
    }
}
//输出
d=17.0
d1=12.0
l=13
d2=8.0

Random

public class RandomDemo {
    public static void main(String[] args) {
        for (int x=0;x<10;x++)
        {
            double d = Math.random();
            sop(d);
        }
    }
    public static void  sop(Object obj)
    {
        System.out.println(obj);
    }
}
//输出 [0,1)
0.44362060760626965
0.786069912604457
0.7456806158981336
0.41908432061119616
0.5847469756217509
0.4770086241970416
0.3620804547796914
0.7859736838982817
0.0018884731926712695
0.01182912216363452

public class RandomDemo {
    public static void main(String[] args) {
        for (int x=0;x<10;x++)
        {
            int d = (int)(Math.random()*10 + 1);
            sop(d);
        }
    }
    public static void  sop(Object obj)
    {
        System.out.println(obj);
    }
}
//输出 [1,10]
1
10
5
6
10
2
3
10
4
10

import java.util.Random;

public class RandomDemo {
    public static void main(String[] args) {
        Random r = new Random();
        for (int x=0;x<10;x++)
        {
            int d = r.nextInt(10)+1;
            sop(d);
        }
    }
    public static void  sop(Object obj)
    {
        System.out.println(obj);
    }
}
//输出 [1,10]
1
2
5
3
10
3
8
4
2
2