Path: csiph.com!news.mixmin.net!news.albasani.net!.POSTED!not-for-mail
From: Sebastian <news@seyweiler.dyndns.org>
Newsgroups: comp.lang.java.programmer
Subject: Random permutations [was Re: Libraries for sysadmins?]
Date: Sat, 05 Mar 2016 00:56:51 +0100
Organization: albasani.net
Lines: 33
Message-ID: <nbd7c3$3jp$1@news.albasani.net>
References: <2cec6af2-9636-4a2a-8849-b01286c0814c@googlegroups.com>  <sysadmins-20160304161143@ram.dialup.fu-berlin.de>  <djttl0Fct5hU1@mid.individual.net> <dju62bFf4ouU1@mid.individual.net> <concise-20160304210431@ram.dialup.fu-berlin.de>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 8bit
X-Trace: news.albasani.net C+r95DPoqXobaOGZSn+cwVUXK4x+/yqqNmgwnRYA25ciwHA+WHKN3EXKQvkzTUZ4R6KD8EZpP3g2CJJ0OL3kqQ==
NNTP-Posting-Date: Fri, 4 Mar 2016 23:56:51 +0000 (UTC)
Injection-Info: news.albasani.net; logging-data="bbIduCK18uRbbRPlQt3bp+Wui364RbwAZxEsAm78xPtS4z2MWjV1l79MmHpFaQPNyD3sp+UCWycsQzB5Wbq7mssAOFmmI6tlMaxRD8c6Raad6jo7pfXrrPPYehTjoM6v"; mail-complaints-to="abuse@albasani.net"
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0
In-Reply-To: <concise-20160304210431@ram.dialup.fu-berlin.de>
Cancel-Lock: sha1:AuS5caJS3gE4JZrbwqtcpc2RnI0=
Xref: csiph.com comp.lang.java.programmer:33925

Am 04.03.2016 21:13, schrieb Stefan Ram:
[snip]
>
>    I like to investigate how to concisely write a program to print
>    numbers simulating the German lotto »6 from 49«, where six
>    numbers are chosen from 1..49 in different programming languages.
>
>    Here is my Java version:
>
> public class Main
> { public static void main( final java.lang.String[] args )
>    { final java.util.List<java.lang.Integer> numbers =
>      java.util.stream.IntStream.rangeClosed( 1, 49 ).boxed().
>      collect( java.util.stream.Collectors.toList() );
>      java.util.Collections.shuffle( numbers );
>      java.lang.System.out.println( numbers.subList( 0, 6 ) ); }}
>
[snip]

This is good if you need about as many elements in the result as are in 
the range. But if the range is large and you need only a few elements, 
it may be better to generate numbers (without duplicates), like this:

new Random().ints(1, 50).distinct().limit(6)

[Side note, not relevant to the lotto example: IntStream#distinct() uses 
a LinkedHashSet internally, so that the order is maintained, as required 
by the java docs for Stream#distinct().]

-- Sebastian

PS: Whoever taught you to qualify the name of classes from java.lang?