//取整，返回小于目標(biāo)函數(shù)的最大整數(shù),如下將會返回-2 Math.floor(-1.8)； //取整，返回發(fā)育目標(biāo)數(shù)的最小整數(shù) Math.ceil() //四舍五入取整 Math.round() //計(jì)算平方根 Math.sqrt() //計(jì)算立方根 Math.cbrt() //返回歐拉數(shù)e的n次冪 Math.exp(3); //計(jì)算乘方,下面是計(jì)算3的2次方 Math.pow(3,2); //計(jì)算自然對數(shù) Math.log(); //計(jì)算絕對值 Math.abs(); //計(jì)算最大值 Math.max(2.3,4.5); //計(jì)算最小值 Math.min(,); //返回一個偽隨機(jī)數(shù)，該數(shù)大于等于0.0并且小于1.0 Math.random 

import java.util.Arrays; import java.util.Random;  public class RandomTest {    /**    * @param args    */   public static void main(String[] args) {     // TODO Auto-generated method stub     Random rand = new Random();     System.out.println("隨機(jī)布爾數(shù)" + rand.nextBoolean());     byte[] buffer = new byte[16];     rand.nextBytes(buffer);     //生產(chǎn)一個含有16個數(shù)組元素的隨機(jī)數(shù)數(shù)組     System.out.println(Arrays.toString(buffer));          System.out.println("rand.nextDouble()" + rand.nextDouble());          System.out.println("Float浮點(diǎn)數(shù)" + rand.nextFloat());          System.out.println("rand.nextGaussian" + rand.nextGaussian());          System.out.println("" + rand.nextInt());          //生產(chǎn)一個0～32之間的隨機(jī)整數(shù)     System.out.println("rand.nextInt(32)" + rand.nextInt(32));          System.out.println("rand.nextLong" + rand.nextLong());   }  } 

ThreadLocalRandom trand= ThreadLocalRandom.current();    int val = rand.nextInt(4,64);