Summary of Common Functions of Math Class in Java

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//Summary of several commonly used mathematical formulas in Java:-2 
Round to the nearest integer, return the largest integer less than the target function, as follows it will return-1.8Math.floor( 
//); 
Round to the nearest integer, return the smallest integer of the development target number 
//Math.ceil() 
Round to the nearest integer 
//Math.round() 
Calculate the square root 
//Math.sqrt() 
Calculate the cube root 
//Math.cbrt() 
Returns the nth power of Euler's number e3); 
//Math.exp(3Calculate the power, the following is the calculation of2power 
Math.pow(3,2); 
//Calculate the natural logarithm 
Math.log(); 
//Calculate the absolute value 
Math.abs(); 
//Calculate the maximum value 
Math.max(2.3,4.5); 
//Calculate the minimum value 
Math.min(,); 
//returns a pseudo-random number, which is greater than or equal to 0.0 and less than1.0 
Math.random 

The Random class is specifically used to generate a pseudo-random number, it has two constructors: one constructor uses the default seed (the current time as the seed), and the other constructor requires the programmer to explicitly pass a long integer seed.

The Random class provides more ways to generate various pseudo-random numbers than the Math.random() method.

e.g

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("Random boolean number" + rand.nextBoolean()); 
    byte[] buffer = new byte[16]; 
    rand.nextBytes(buffer); 
    //Generate an array containing16An array of random numbers of elements 
    System.out.println(Arrays.toString(buffer)); 
    System.out.println("rand.nextDouble()"} + rand.nextDouble()); 
    System.out.println("Float floating-point number" + rand.nextFloat()); 
    System.out.println("rand.nextGaussian" + rand.nextGaussian()); 
    System.out.println("" + rand.nextInt()); 
    //generate a 0～32random integer between 
    System.out.println("rand.nextInt(32)" + rand.nextInt(32)); 
    System.out.println("rand.nextLong" + rand.nextLong()); 
  } 
} 

To avoid two Random objects generating the same number sequence, it is usually recommended to use the current time as the seed of the Random object, as shown in the following code:

Random rand = new Random(System.currentTimeMillis());

in java7where ThreadLocalRandom is introduced

The way to use ThreadLocalRandom in a multi-threaded environment is similar to using Random, as the following program snippet demonstrates the usage of ThreadLocalRandom:

Firstly, use current() to generate a random sequence, and then use nextCXxx() to generate the desired pseudo-random sequence:

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

generate4～64pseudo-random numbers between

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