package org.hanqi.array;

 import java.util.Random;

 public class BaoZhuang {

     public static void main(String[] args) {

         //包装类

         Long l = new Long(100);

         //把字符串转成数值

         Long l1 = new Long("1000");

         String str = 1000 + "";

         //从包装类转成基本数据类型

         long l2 = l1.longValue();

         System.out.println("l2="+l2);

         long l3 = Long.parseLong("1200");

         System.out.println(l3);

         //int

         Integer i = new Integer("100");

         Integer.parseInt("100");

         //float

         Float f = new Float("123.45");

         Float.parseFloat("123.45");

         //double

         Double d = new Double("12345.67");

         Double.parseDouble("123.78");

         //boolean

         Boolean b = new Boolean("ture");

         System.out.println(b.booleanValue());

         //数学工具类

         System.out.println(Math.PI);

         //四舍五入

         System.out.println(Math.round(1234.46789));

         double de = 1234.5678;

         System.out.println(Math.round(de));

         //保留小数点后2位

         System.out.println(Math.round(de*100)/100.0);

         //舍去小数点后的数字

         //下限值：小于或等于它的最大整数

         System.out.println(Math.floor(de));

         //上限值：大于或等于它的最小整数

         double de1 = 1234.06;

         System.out.println(Math.ceil(de1));

         //随机数 0-1 之间

         System.out.println(Math.random());

         System.out.println(Math.random());

         System.out.println(Math.random());

         System.out.println(Math.random());

         System.out.println();

         Random r = new Random();

         //随机数种子

         //伪随机数

         //根据种子计算

         //r = new Random(1);

         //默认使用时间做种子

         for(int m=0;m<10;m++)

         {

             System.out.println(r.nextInt(100));//限定范围的随机

         }

     }

 }