Cum se generează un număr aleatoriu în Java cu unele variații?

Publicat: 2019-02-27
crocant cu numere aleatorii

În Java, există o metodă random() în clasa Math , care returnează o valoare dublă între 0.0 and 1.0 . În clasa Random există o metodă nextInt(int n) , care returnează o valoare aleatorie în intervalul 0 (inclusiv) și n (exclusiv).

Sunt sigur că trebuie să te fi confruntat cu întrebările de mai jos în trecut:

  • Cum se generează numere aleatorii în Java?
  • Generarea unui număr aleator într-un interval cu Java
  • Unde pot găsi exemple de numere aleatorii Java?
  • Exemplu de metodă Java.lang.Math.random().

Iată un exemplu simplu care utilizează funcția Random() și oferă răspuns la toate întrebările dvs.

Cum se generează un număr aleatoriu în Java cu unele variații?

Iată ce facem noi aici:

  • Creați metoda RandomTest1 () care este un test simplu care tipărește un număr aleator între numărul min și maxim (Exemplu de interval de numere).
  • Creați metoda RandomTest2 () care este un test simplu care imprimă o intrare aleatorie din listă.
  • Creați Two Threads în principal și run metoda Main.
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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 ( ) ;
     }
 
}
 

Ieșire consola Eclipse:

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/ 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 - 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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 )
 

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