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Posted to issues@commons.apache.org by "Alexander van de Rovaart (Jira)" <ji...@apache.org> on 2021/02/04 12:04:00 UTC
[jira] [Updated] (LANG-1643) Initialize ArrayList in EqualsBuilder
constructor with size 1
[ https://issues.apache.org/jira/browse/LANG-1643?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Alexander van de Rovaart updated LANG-1643:
-------------------------------------------
Summary: Initialize ArrayList in EqualsBuilder constructor with size 1 (was: Initialize Arraylist in EqualsBuilder with size 1)
> Initialize ArrayList in EqualsBuilder constructor with size 1
> -------------------------------------------------------------
>
> Key: LANG-1643
> URL: https://issues.apache.org/jira/browse/LANG-1643
> Project: Commons Lang
> Issue Type: Improvement
> Components: lang.builder.*
> Environment: {code}
> :~$ java -version
> openjdk version "11.0.9.1" 2020-11-04
> OpenJDK Runtime Environment (build 11.0.9.1+1-Ubuntu-0ubuntu1.20.04)
> OpenJDK 64-Bit Server VM (build 11.0.9.1+1-Ubuntu-0ubuntu1.20.04, mixed mode, sharing)
> :~$ uname -a
> Linux ubuntu 5.8.0-41-generic #46~20.04.1-Ubuntu SMP Mon Jan 18 17:52:23 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
> Apache commons lang3 version 3.11
> {code}
> Reporter: Alexander van de Rovaart
> Priority: Minor
> Labels: EqualsBuilder, improvement
> Attachments: image-2021-02-04-11-45-47-437.png, screenshot-1.png
>
>
> In the constructor the EqualsBuilder the variabele {{bypassReflectionClasses}} is initialized with an {{new ArrayList()}} and immidiately after that a vaue is added. This will result in an ArrayList.grow() because the contructor of ArrayList will initialize is with a zero length array. See attached screenshots for a stacktrace from a flight recording.
> My suggestion would be to initialize the arraylist with a length of 1 (or the default of 10 that is used in {{java.util.ArrayList}} when it is initially grown on the first add.) So the calls to {{ArrayList.grow}} and {{ArrayList.newCapacity}} and {{Arrays.copyOf}} won't be called when calling the add function after construction.
>
> So the code sample of the constructor would be:
> {code:java}
> public EqualsBuilder() {
> // set up default classes to bypass reflection for
> bypassReflectionClasses = new ArrayList<>(1);
> bypassReflectionClasses.add(String.class); //hashCode field being lazy but not transient
> }
> {code}
> !image-2021-02-04-11-45-47-437.png!
> !screenshot-1.png!
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