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https://issues.apache.org/jira/browse/MCHECKSTYLE-345?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16266109#comment-16266109
]
Robert Scholte commented on MCHECKSTYLE-345:
--------------------------------------------
When running Maven with an additional {{-e}} you'll see the following
stacktrace:
{noformat}
Caused by: java.lang.NullPointerException
at
com.puppycrawl.tools.checkstyle.checks.blocks.NeedBracesCheck.isSingleLineFor
(NeedBracesCheck.java:286)
at
com.puppycrawl.tools.checkstyle.checks.blocks.NeedBracesCheck.isSingleLineStatement
(NeedBracesCheck.java:203)
at
com.puppycrawl.tools.checkstyle.checks.blocks.NeedBracesCheck.isSkipStatement
(NeedBracesCheck.java:177)
at com.puppycrawl.tools.checkstyle.checks.blocks.NeedBracesCheck.visitToken
(NeedBracesCheck.java:164)
at com.puppycrawl.tools.checkstyle.TreeWalker.notifyVisit
(TreeWalker.java:388)
at com.puppycrawl.tools.checkstyle.TreeWalker.processIter
(TreeWalker.java:499)
at com.puppycrawl.tools.checkstyle.TreeWalker.walk (TreeWalker.java:330)
at com.puppycrawl.tools.checkstyle.TreeWalker.processFiltered
(TreeWalker.java:203)
at com.puppycrawl.tools.checkstyle.api.AbstractFileSetCheck.process
(AbstractFileSetCheck.java:79)
at com.puppycrawl.tools.checkstyle.Checker.process (Checker.java:265)
at
org.apache.maven.plugin.checkstyle.exec.DefaultCheckstyleExecutor.executeCheckstyle
(DefaultCheckstyleExecutor.java:252)
{noformat}
This shows that it is not the maven-plugin, but Checkstyle causes the NPE.
Please visit http://checkstyle.sourceforge.net/ and file your issue there.
> Checkstyle crashes on NPE when for loop without braces has direct if with
> braces
> --------------------------------------------------------------------------------
>
> Key: MCHECKSTYLE-345
> URL: https://issues.apache.org/jira/browse/MCHECKSTYLE-345
> Project: Maven Checkstyle Plugin
> Issue Type: Bug
> Affects Versions: 2.17
> Environment: ubuntu 16.04, confirmed on windows 10 too
> Reporter: Marek Sabo
> Labels: build
> Attachments: issue-NPE-project.zip
>
> Original Estimate: 128h
> Remaining Estimate: 128h
>
> Hello,
> I would like to inform you that the following code causes checkstyle to crash:
> {code:java}
> class Demo {
> public static void main(String[] args) {
> for (int i = 0; i < 5; i++)
> if (1 < 2) {
> System.out.println("Multiple line if block");
> }
> }
> }
> {code}
> It happens when an `for` loop without braces contains nested `if` with curly
> braces inside.
> $ mvn clean install
> {code:txt}
> [INFO] Scanning for projects...
> [INFO]
>
> [INFO]
> ------------------------------------------------------------------------
> [INFO] Building temp 1.0-SNAPSHOT
> [INFO]
> ------------------------------------------------------------------------
> [INFO]
> [INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ temp ---
> [INFO] Deleting /home/mrek/temp/temp/target
> [INFO]
> [INFO] --- maven-checkstyle-plugin:2.17:check (validate) @ temp ---
> [INFO]
> ------------------------------------------------------------------------
> [INFO] BUILD FAILURE
> [INFO]
> ------------------------------------------------------------------------
> [INFO] Total time: 1.856 s
> [INFO] Finished at: 2017-11-26T17:26:49+01:00
> [INFO] Final Memory: 12M/195M
> [INFO]
> ------------------------------------------------------------------------
> [ERROR] Failed to execute goal
> org.apache.maven.plugins:maven-checkstyle-plugin:2.17:check (validate) on
> project temp: Execution validate of goal
> org.apache.maven.plugins:maven-checkstyle-plugin:2.17:check failed.
> NullPointerException -> [Help 1]
> [ERROR]
> [ERROR] To see the full stack trace of the errors, re-run Maven with the -e
> switch.
> [ERROR] Re-run Maven using the -X switch to enable full debug logging.
> [ERROR]
> [ERROR] For more information about the errors and possible solutions, please
> read the following articles:
> [ERROR] [Help 1]
> http://cwiki.apache.org/confluence/display/MAVEN/PluginExecutionException
> {code}
> Although I can agree that the code above is not nice at all, it is definitely
> a bug.
> I can agree that the best way to avoid it is to to not write code like this
> at all, but our students sometimes write code like this and then they have
> surely no idea why the build is failing.
> Please see the simple project in the attachment (just this Demo.java with pom
> and config).
> I am also adding output of those files:
> config.xml
> {code:xml}
> <?xml version="1.0"?>
> <!DOCTYPE module PUBLIC
> "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
> "http://www.puppycrawl.com/dtds/configuration_1_3.dtd";>
> <module name="Checker">
> <module name="TreeWalker">
> <module name="NeedBraces">
> <property name="allowSingleLineStatement" value="true"/>
> </module>
> </module>
> </module>
> <?xml version="1.0"?>
> <!DOCTYPE module PUBLIC
> "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
> "http://www.puppycrawl.com/dtds/configuration_1_3.dtd";>
> <module name="Checker">
> <module name="TreeWalker">
> <module name="NeedBraces">
> <property name="allowSingleLineStatement" value="true"/>
> </module>
> </module>
> </module>
> {code}
> pom.xml
> {code:xml}
> <?xml version="1.0" encoding="UTF-8"?>
> <project xmlns="http://maven.apache.org/POM/4.0.0";
> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
> xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
> http://maven.apache.org/xsd/maven-4.0.0.xsd";>
> <modelVersion>4.0.0</modelVersion>
> <groupId>temp</groupId>
> <artifactId>temp</artifactId>
> <version>1.0-SNAPSHOT</version>
> <build>
> <plugins>
> <plugin>
> <groupId>org.apache.maven.plugins</groupId>
> <artifactId>maven-checkstyle-plugin</artifactId>
> <version>2.17</version>
> <executions>
> <execution>
> <id>validate</id>
> <phase>validate</phase>
> <configuration>
> <configLocation>config.xml</configLocation>
> </configuration>
> <goals>
> <goal>check</goal>
> </goals>
> </execution>
> </executions>
> </plugin>
> </plugins>
> </build>
> </project>
> {code}
> I hope it is an easy fix and could be resolved!
> Thank you,
> Marek
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