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https://issues.apache.org/jira/browse/CASSANDRA-17925?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17638417#comment-17638417
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Stefan Miklosovic commented on CASSANDRA-17925:
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Hi [~mmuzaf] 

I saw your thread on ML, feel free to take a lead in this one if you wish. I ll 
gladly review it. We need to define what order we actually want. My idea was to 
look around other Apache projects how they are enforcing this and what style 
they use (if any).

The outcome of this effort should be a defined checkstyle on imports and we 
should include this to trunk only. Documentation should be updated as well. 

I think this is quite an important change and I would prefer to have a separate 
discussion on ML dedicated to this issue. I am not completely sure what other 
developers prefer and it seems to be kind of change everybody should be 
comfortable with in the long run. We will touch almost all classes in Cassandra 
code base and getting this right from the start is crucial. 

> Java source code should have sorted imports as defined in the codestyle
> -----------------------------------------------------------------------
>
>                 Key: CASSANDRA-17925
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-17925
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Stefan Miklosovic
>            Priority: Normal
>
> After we cleaned all unused imports in CASSANDRA-17876, there is one more 
> task remaining to be done - to add checkstyle for imports order and enforce 
> this on build time.
> When the project is imported into IDEA, there is a helper target on Ant 
> called "generate-idea-files". ide/idea/codeStyleSettings.xml contains this:
> {code:java}
>         <option name="IMPORT_LAYOUT_TABLE">
>           <value>
>             <package name="java" withSubpackages="true" static="false" />
>             <package name="javax" withSubpackages="true" static="false" />
>             <emptyLine />
>             <package name="com.google.common" withSubpackages="true" 
> static="false" />
>             <package name="org.apache.log4j" withSubpackages="true" 
> static="false" />
>             <package name="org.apache.commons" withSubpackages="true" 
> static="false" />
>             <package name="org.cliffc.high_scale_lib" withSubpackages="true" 
> static="false" />
>             <package name="org.junit" withSubpackages="true" static="false" />
>             <package name="org.slf4j" withSubpackages="true" static="false" />
>             <emptyLine />
>             <package name="" withSubpackages="true" static="false" />
>             <emptyLine />
>             <package name="" withSubpackages="true" static="true" />
>           </value>
>         </option>
> {code}
> This code style is also mentioned in the web page here (minus some details 
> which are present in above configuration snippet but not on the web page): 
> [https://cassandra.apache.org/_/development/code_style.html] (at the very 
> bottom).
> However, when one runs "Optimise imports" in the context menu after 
> right-clicking on org.cassandra.apache package, it will refactor the imports 
> and it results with hundreds of changes.
> This means that the source code, as-is, does not adhere to the self-imposed 
> code style we ship for IDEA.
> If we fix this, we should add checkstyle for it like this:
> {code:java}
>     <module name="ImportOrder">
>       <property name="groups" 
> value="/(^java\.|javax)/,/(com\.google\.common|org\.apache\.log4j|org\.apache\.commons|org\.cliffc\.high_scale_lib|org\.junit|org\.slf4j)/"/>
>       <property name="ordered" value="true"/>
>       <property name="separated" value="true"/>
>       <property name="option" value="bottom"/>
>       <property name="separatedStaticGroups" value="false"/>
>       <property name="sortStaticImportsAlphabetically" value="true"/>
>     </module>
> {code}
> This checkstyle on import order will pass on the source code we run the 
> import optimization in the context menu on.
> There is also no enforcement on "all star" imports (org.some.pkg.*). 
> Checkstyle has specific module for this: 
> [https://checkstyle.org/config_imports.html#AvoidStarImport] 
> I propose we should stop to use all-star imports. Same argument holds as 
> described there: Rationale: Importing all classes from a package or static 
> members from a class leads to tight coupling between packages or classes and 
> might lead to problems when a new version of a library introduces name 
> clashes.
> This should be applied to test checktyle as well and the source code should 
> be refactored on imports too.
> This should be done on cassandra-4.1 as well as for trunk.



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