//取整，返回小于目標(biāo)函數(shù)的最大整數(shù),如下將會(huì)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(duì)數(shù) 
Math.log(); 
//計(jì)算絕對(duì)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(gè)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(gè)含有16個(gè)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(gè)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);