Wie generiert man Zufallszahlen in Java mit einigen Variationen?

Veröffentlicht: 2019-02-27
Zufallszahl crunchify

In Java gibt es eine Methode random() in der Math -Klasse, die einen Double-Wert zwischen 0.0 and 1.0 zurückgibt. In der Klasse Random gibt es eine Methode nextInt(int n) , die einen Zufallswert im Bereich von 0 (inklusive) und n (exklusive) zurückgibt.

Ich bin sicher, dass Sie in der Vergangenheit mit den folgenden Fragen konfrontiert waren:

  • Wie generiert man Zufallszahlen in Java?
  • Generieren einer Zufallszahl in einem Bereich mit Java
  • Wo finde ich Beispiele für Java-Zufallszahlen?
  • Java.lang.Math.random()-Methodenbeispiel

Hier ist ein einfaches Beispiel, das die Funktion Random() verwendet und Antworten auf alle Ihre Fragen bietet.

Wie generiert man Zufallszahlen in Java mit einigen Variationen?

Das machen wir hier:

  • Erstellen Sie die Methode RandomTest1 (), die ein einfacher Test ist, der eine Zufallszahl zwischen der minimalen und der maximalen Anzahl ausgibt (Beispiel für einen Zahlenbereich).
  • Erstellen Sie die Methode RandomTest2 (), die ein einfacher Test ist, der zufällige Einträge aus der Liste druckt.
  • Erstellen Sie Two Threads in main und run Sie die Main-Methode aus.
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 ( ) ;
     }
 
}
 

Ausgabe der Eclipse-Konsole:

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 )
 

Vielleicht möchten Sie sich mehr als 500 Tutorials zu Java ansehen.