/*
* Math常见的方法
* Random r = new Random(); 使用默认当前系统时间的毫秒数作为种子数
* Random r = new Random(100) 使用自己指定的种子数
* 如果两个对象的参数相同,则生成的随机数相同(在一个for循环里面,种子数相同的两个对象,生成的随机数相同
*/import java.util.Random;publicclassMathRandom{publicstaticvoidmain(String[] args){// TODO Auto-generated method stub// demo1();demo2();}privatestaticvoiddemo2(){//创建一个Random对象
Random r =newRandom();for(int i =0; i <5; i++){
System.out.println(r.nextInt());}
System.out.println("-------------");
Random r2 =newRandom(100);
Random r3 =newRandom(100);// int a = r2.nextInt();// int b = r2.nextInt();// System.out.println(a);// System.out.println(b);for(int i =0; i <5; i++){
System.out.println(r2.nextInt());//打印的两次的值一样
System.out.println(r3.nextInt());}}privatestaticvoiddemo1(){
System.out.println(Math.PI);//3.141592653589793
System.out.println(Math.random());//随机数在0-1取 0.613681695289803
System.out.println(Math.sqrt(16));//开平方根 4.0
System.out.println(Math.round(3.4));//四舍五入 3
System.out.println(Math.round(3.6));// 4
System.out.println(Math.pow(3.0,3.0));//立方数几的几次方 27.0
System.out.println(Math.floor(3.4));//向下取整 3.0
System.out.println(Math.floor(3.6));// 3.0
System.out.println(Math.ceil(3.4));//向上取整 4.0
System.out.println(Math.ceil(3.6));// 4.0
System.out.println(Math.abs(-2));//取绝对值 2}}
