如何在 Java 中生成具有一些变化的随机数？

已发表: 2019-02-27
随机数压缩

在 Java 中， Math类中有一个方法random() ，它返回一个介于0.0 and 1.0之间的双精度值。 在 Random 类中有一个方法nextInt(int n) ，它返回 0（包括）和 n（不包括）范围内的随机值。

我相信您过去一定遇到过以下问题：

  • 如何在 Java 中生成随机数？
  • 使用Java生成范围内的随机数
  • 我在哪里可以找到 Java 随机数示例？
  • Java.lang.Math.random() 方法示例

这是一个使用 Random() 函数并为您所有问题提供答案的简单示例。

如何在 Java 中生成具有一些变化的随机数？

这就是我们在这里所做的：

  • 创建方法RandomTest1 () 这是一个简单的测试，它打印最小和最大数字之间的随机数（数字范围示例）。
  • 创建方法RandomTest2 () 这是一个简单的测试，它从列表中打印随机条目。
  • 在 main 中创建Two Threads并run Main 方法。
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
package crunchify . com . tutorials ;
 
import java . util . ArrayList ;
import java . util . List ;
import java . util . Random ;
 
/**
* @author Crunchify.com
* How to Generate Random Number in Java with Some Variations?
*/
 
public class CrunchifyRandomNumber {
 
     // Simple test which prints random number between min and max number (Number Range Example)
     public void RandomTest1 ( ) throws InterruptedException {
         while ( true ) {
             int min = 50 ;
             int max = 100 ;
 
             // random() returns a double value with a positive sign, greater than or equal to 0.0 and less than 1.0.
// Returned values are chosen pseudorandomly with (approximately) uniform distribution from that range.
             float randomNumber = ( min + ( float ) ( Math . random ( ) * ( ( max - min ) ) ) ) ;
             System . out . println ( "Crunchify Thread 1 random result: " + randomNumber ) ;
 
             // sleep() causes the currently executing thread to sleep (temporarily cease execution) for the specified number of milliseconds,
             // subject to the precision and accuracy of system timers and schedulers.
             // The thread does not lose ownership of any monitors.
             Thread . sleep ( 500 ) ;
         }
     }
 
     // Simple test which prints random entry from list below
     public void RandomTest2 ( ) throws InterruptedException {
         List < String > list = new ArrayList < String > ( ) ;
         list . add ( "Facebook" ) ;
         list . add ( "Twitter" ) ;
         list . add ( "Google" ) ;
 
         Random randomNumber = new Random ( ) ;
         String randomEle ;
         int listSize = list . size ( ) ;
 
         while ( true ) {
             randomEle = list . get ( randomNumber . nextInt ( listSize ) ) ;
             System . out . println ( "Crunchify Thread 2 random result: " + randomEle ) ;
             Thread . sleep ( 500 ) ;
         }
     }
 
     static public void main ( String [ ] args ) {
 
         // Let's run both Test1 and Test2 methods in parallel..
         Thread crunchifyThread1 = new Thread ( ) {
             public void run ( ) {
                 CrunchifyRandomNumber crNumber = new CrunchifyRandomNumber ( ) ;
                 try {
                     crNumber . RandomTest1 ( ) ;
                 } catch ( InterruptedException e ) {
                     e . printStackTrace ( ) ;
                 }
             }
         } ;
         Thread crunchifyThread2 = new Thread ( ) {
             public void run ( ) {
                 CrunchifyRandomNumber crNumber = new CrunchifyRandomNumber ( ) ;
                 try {
                     crNumber . RandomTest2 ( ) ;
                 } catch ( InterruptedException e ) {
                     e . printStackTrace ( ) ;
                 }
             }
         } ;
 
         // start() Causes this thread to begin execution; the Java Virtual Machine calls the run method of this thread.
//The result is that two threads are running concurrently: the current thread
// (which returns from the call to the start method) and the other thread (which executes its run method).
         crunchifyThread1 . start ( ) ;
         crunchifyThread2 . start ( ) ;
     }
 
}
 

Eclipse 控制台输出：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
/ Library / Java / JavaVirtualMachines / jdk - 15.jdk / Contents / Home / bin / java - javaagent : / Applications / IntelliJ IDEA . app / Contents / lib / idea_rt . jar = 55975 : / Applications / IntelliJ IDEA . app / Contents / bin - Dfile . encoding = UTF - 8 - classpath / Users / app / crunchify / github / CrunchifyTutorials / target / classes : / Users / app / crunchify / github / CrunchifyTutorials / WebContent / WEB - INF / lib / zxing - 2.1.jar : / Users / app / crunchify / github / CrunchifyTutorials / WebContent / WEB - INF / lib / commons - logging - 1.1.2.jar : / Users / app / crunchify / github / CrunchifyTutorials / WebContent / WEB - INF / lib / commons - collections - 3.2.1.jar : / Users / app / crunchify / github / CrunchifyTutorials / WebContent / WEB - INF / lib / javax . mail . jar : / Users / app / crunchify / github / CrunchifyTutorials / WebContent / WEB - INF / lib / commons - io - 2.4.jar : / Users / app / crunchify / github / CrunchifyTutorials / WebContent / WEB - INF / lib / commons - lang - 2.6.jar : / Users / app / crunchify / github / CrunchifyTutorials / WebContent / WEB - INF / lib / commons - configuration - 1.9.jar : / Users / app / crunchify / github / CrunchifyTutorials / WebContent / WEB - INF / lib / log4j - 1.2.17.jar : / Users / app / crunchify / github / CrunchifyTutorials / WebContent / WEB - INF / lib / commons - beanutils - 1.8.3.jar : / Users / app / . m2 / repository / org / glassfish / javax . json / 1.0.4 / javax . json - 1.0.4.jar : / Users / app / . m2 / repository / com / github / wnameless / json - flattener / 0.2.2 / json - flattener - 0.2.2.jar : / Users / app / . m2 / repository / com / eclipsesource / minimal - json / minimal - json / 0.9.4 / minimal - json - 0.9.4.jar : / Users / app / . m2 / repository / org / apache / commons / commons - lang3 / 3.10 / commons - lang3 - 3.10.jar : / Users / app / . m2 / repository / com / google / code / gson / gson / 2.8.0 / gson - 2.8.0.jar : / Users / app / . m2 / repository / net / jodah / expiringmap / 0.5.7 / expiringmap - 0.5.7.jar : / Users / app / . m2 / repository / org / apache / httpcomponents / httpclient / 4.3.6 / httpclient - 4.3.6.jar : / Users / app / . m2 / repository / org / apache / httpcomponents / httpcore / 4.3.3 / httpcore - 4.3.3.jar : / Users / app / . m2 / repository / commons - codec / commons - codec / 1.6 / commons - codec - 1.6.jar : / Users / app / . m2 / repository / org / json / json / 20151123 / json - 20151123.jar : / Users / app / . m2 / repository / net / spy / spymemcached / 2.12.3 / spymemcached - 2.12.3.jar : / Users / app / . m2 / repository / com / whalin / Memcached - Java - Client / 3.0.2 / Memcached - Java - Client - 3.0.2.jar : / Users / app / . m2 / repository / commons - pool / commons - pool / 1.5.6 / commons - pool - 1.5.6.jar : / Users / app / . m2 / repository / org / slf4j / slf4j - api / 1.6.4 / slf4j - api - 1.6.4.jar : / Users / app / . m2 / repository / com / googlecode / xmemcached / xmemcached / 2.4.5 / xmemcached - 2.4.5.jar : / Users / app / . m2 / repository / com / paypal / sdk / rest - api - sdk / 1.14.0 / rest - api - sdk - 1.14.0.jar : / Users / app / . m2 / repository / commons - dbcp / commons - dbcp / 20030825.184428 / commons - dbcp - 20030825.184428.jar : / Users / app / . m2 / repository / javax / ws / rs / javax . ws . rs - api / 2.0 / javax . ws . rs - api - 2.0.jar : / Users / app / . m2 / repository / org / hamcrest / hamcrest - all / 1.3 / hamcrest - all - 1.3.jar : / Users / app / . m2 / repository / log4j / log4j / 1.2.17 / log4j - 1.2.17.jar : / Users / app / . m2 / repository / com / google / guava / guava / 19.0 / guava - 19.0.jar : / Users / app / . m2 / repository / com / googlecode / json - simple / json - simple / 1.1 / json - simple - 1.1.jar : / Users / app / . m2 / repository / commons - net / commons - net / 2.0 / commons - net - 2.0.jar : / Users / app / . m2 / repository / asm / asm / 3.3.1 / asm - 3.3.1.jar : / Users / app / . m2 / repository / axis / axis / 1.4 / axis - 1.4.jar : / Users / app / . m2 / repository / org / apache / axis / axis - jaxrpc / 1.4 / axis - jaxrpc - 1.4.jar : / Users / app / . m2 / repository / axis / axis - wsdl4j / 1.5.1 / axis - wsdl4j - 1.5.1.jar : / Users / app / . m2 / repository / commons - beanutils / commons - beanutils / 1.8.3 / commons - beanutils - 1.8.3.jar : / Users / app / . m2 / repository / commons - collections / commons - collections / 3.2.1 / commons - collections - 3.2.1.jar : / Users / app / . m2 / repository / commons - configuration / commons - configuration / 1.10 / commons - configuration - 1.10.jar : / Users / app / . m2 / repository / commons - io / commons - io / 2.4 / commons - io - 2.4.jar : / Users / app / . m2 / repository / commons - discovery / commons - discovery / 0.5 / commons - discovery - 0.5.jar : / Users / app / . m2 / repository / commons - lang / commons - lang / 2.6 / commons - lang - 2.6.jar : / Users / app / . m2 / repository / commons - logging / commons - logging / 1.1.3 / commons - logging - 1.1.3.jar : / Users / app / . m2 / repository / commons - logging / commons - logging - api / 1.1 / commons - logging - api - 1.1.jar : / Users / app / . m2 / repository / javax / mail / mail / 1.4.7 / mail - 1.4.7.jar : / Users / app / . m2 / repository / javax / activation / activation / 1.1 / activation - 1.1.jar : / Users / app / . m2 / repository / javax / xml / jaxrpc - api / 1.1 / jaxrpc - api - 1.1.jar : / Users / app / . m2 / repository / javax / servlet / javax . servlet - api / 3.1.0 / javax . servlet - api - 3.1.0.jar : / Users / app / . m2 / repository / org / apache / axis / axis - saaj / 1.4 / axis - saaj - 1.4.jar : / Users / app / . m2 / repository / wsdl4j / wsdl4j / 1.6.3 / wsdl4j - 1.6.3.jar : / Users / app / . m2 / repository / com / google / zxing / core / 3.2.1 / core - 3.2.1.jar : / Users / app / . m2 / repository / org / apache / commons / commons - compress / 1.9 / commons - compress - 1.9.jar : / Users / app / . m2 / repository / mysql / mysql - connector - java / 5.1.6 / mysql - connector - java - 5.1.6.jar : / Users / app / . m2 / repository / junit / junit / 4.12 / junit - 4.12.jar : / Users / app / . m2 / repository / org / hamcrest / hamcrest - core / 1.3 / hamcrest - core - 1.3.jar : / Users / app / . m2 / repository / ch / qos / logback / logback - classic / 1.2.3 / logback - classic - 1.2.3.jar : / Users / app / . m2 / repository / ch / qos / logback / logback - core / 1.2.3 / logback - core - 1.2.3.jar : / Users / app / . m2 / repository / org / springframework / spring - context / 5.1.3.RELEASE / spring - context - 5.1.3.RELEASE.jar : / Users / app / . m2 / repository / org / springframework / spring - aop / 5.1.3.RELEASE / spring - aop - 5.1.3.RELEASE.jar : / Users / app / . m2 / repository / org / springframework / spring - beans / 5.1.3.RELEASE / spring - beans - 5.1.3.RELEASE.jar : / Users / app / . m2 / repository / org / springframework / spring - core / 5.1.3.RELEASE / spring - core - 5.1.3.RELEASE.jar : / Users / app / . m2 / repository / org / springframework / spring - jcl / 5.1.3.RELEASE / spring - jcl - 5.1.3.RELEASE.jar : / Users / app / . m2 / repository / org / springframework / spring - expression / 5.1.3.RELEASE / spring - expression - 5.1.3.RELEASE.jar : / Users / app / . m2 / repository / org / springframework / spring - context - support / 5.1.3.RELEASE / spring - context - support - 5.1.3.RELEASE.jar crunchify . com . tutorials . CrunchifyRandomNumber
Crunchify Thread 2 random result : Twitter
Crunchify Thread 1 random result : 98.03486
Crunchify Thread 2 random result : Google
Crunchify Thread 1 random result : 57.48709
Crunchify Thread 2 random result : Google
Crunchify Thread 1 random result : 87.54976
Crunchify Thread 2 random result : Google
Crunchify Thread 1 random result : 75.2223
Crunchify Thread 2 random result : Facebook
Crunchify Thread 1 random result : 91.617584
Crunchify Thread 2 random result : Facebook
Crunchify Thread 1 random result : 64.705574
Crunchify Thread 2 random result : Google
Crunchify Thread 1 random result : 72.043884
Crunchify Thread 2 random result : Google
Crunchify Thread 1 random result : 70.38615
Crunchify Thread 2 random result : Facebook
Crunchify Thread 1 random result : 55.705227
Crunchify Thread 2 random result : Facebook
Crunchify Thread 1 random result : 76.36104
Crunchify Thread 2 random result : Twitter
Crunchify Thread 1 random result : 75.84907
 
Process finished with exit code 130 ( interrupted by signal 2 : SIGINT )
 

您可能想查看 500 多篇关于 Java 的教程。