Gradle Checkstyle插件默認與Google Checks不兼容

Question

請注意：我創建了這個GitHub項目來幫助您准確地解決問題 。

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Java 8和Gradle 4.6在這里。 如果您通過gradle init --type java-library創建一個新的Java Gradle項目，然后使用Gradle Checkstyle插件創建它，並將該插件配置為使用Google的Checkstyle XML ，它將立即失敗：

plugins {
    id 'java-library'
}

apply plugin: 'checkstyle'

dependencies {
    testCompile(
        'junit:junit:4.12'
    )
}

repositories {
    jcenter()
    mavenCentral()
}

checkstyle {
    // Go to the Google Checks link above and paste its
    // contents into checkstyle.xml
    config = rootProject.resources.text.fromFile('buildConfig/checkstyle/checkstyle.xml')
}

使用該配置，運行./gradle clean build會產生：

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':checkstyleMain'.
> Unable to create a Checker: configLocation {/Users/myuser/workspace/test-gradle-checkstyle/buildConfig/checkstyle/checkstyle.xml}, classpath {/Users/myuser/workspace/test-gradle-checkstyle/build/classes/java/main:/Users/myuser/workspace/test-gradle-checkstyle/build/resources/main}.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 1s
4 actionable tasks: 4 executed
$ pwd
/Users/myuser/workspace/test-gradle-checkstyle
$ git init
Initialized empty Git repository in /Users/myuser/workspace/test-gradle-checkstyle/.git/

我想知道為什么？！

---

編輯（面向未來的Google員工）：

使用--stacktrace ，實際錯誤是

cannot initialize module TreeWalker - Token "METHOD_REF" was not found in Acceptable tokens list in check com.puppycrawl.tools.checkstyle.checks.whitespace.SeparatorWrapCheck

Answer 1

顯然Gradle使用舊版CheckStyle - 但有一種方法可以解決這個問題！

首先，我建議當你在構建中遇到問題時，使用--stacktrace或-S來查看實際的失敗，通過使用它，你會看到確切的失敗：

cannot initialize module TreeWalker - Token "METHOD_REF" was not found in Acceptable tokens list in check com.puppycrawl.tools.checkstyle.checks.whitespace.SeparatorWrapCheck

這是因為Gradle 4.6使用CheckStyle 6.19，現在已經很老了（最新版本是8.11）升級配置以使用最新解決了這個問題：

checkstyle {
    config = rootProject.resources.text.fromFile('buildConfig/checkstyle/checkstyle.xml')
    toolVersion '8.11'
}

結果是：

> Task :checkstyleMain
[ant:checkstyle] [WARN] /.../test-gradle-checkstyle/src/main/java/Library.java:5: 'method def modifier' has incorrect indentation level 4, expected level should be 2. [Indentation]
[ant:checkstyle] [WARN] /.../test-gradle-checkstyle/src/main/java/Library.java:6: 'method def' child has incorrect indentation level 8, expected level should be 4. [Indentation]
[ant:checkstyle] [WARN] /.../test-gradle-checkstyle/src/main/java/Library.java:7: 'method def rcurly' has incorrect indentation level 4, expected level should be 2. [Indentation]

> Task :checkstyleTest
[ant:checkstyle] [WARN] /.../test-gradle-checkstyle/src/test/java/LibraryTest.java:5: 'import' should be separated from previous statement. [EmptyLineSeparator]
[ant:checkstyle] [WARN] /.../test-gradle-checkstyle/src/test/java/LibraryTest.java:5: Import statement for 'org.junit.Assert.*' is in the wrong order. Should be in the 'STATIC' group, expecting not assigned imports on this line. [CustomImportOrder]
[ant:checkstyle] [WARN] /.../test-gradle-checkstyle/src/test/java/LibraryTest.java:5: Using the '.*' form of import should be avoided - org.junit.Assert.*. [AvoidStarImport]
[ant:checkstyle] [WARN] /.../test-gradle-checkstyle/src/test/java/LibraryTest.java:8: 'method def modifier' has incorrect indentation level 4, expected level should be 2. [Indentation]
[ant:checkstyle] [WARN] /.../test-gradle-checkstyle/src/test/java/LibraryTest.java:9: 'method def' child has incorrect indentation level 8, expected level should be 4. [Indentation]
[ant:checkstyle] [WARN] /.../test-gradle-checkstyle/src/test/java/LibraryTest.java:10: 'method def' child has incorrect indentation level 8, expected level should be 4. [Indentation]
[ant:checkstyle] [WARN] /.../test-gradle-checkstyle/src/test/java/LibraryTest.java:11: 'method def rcurly' has incorrect indentation level 4, expected level should be 2. [Indentation]


BUILD SUCCESSFUL in 9s
7 actionable tasks: 7 executed

在Gradle項目和CheckStyle項目中，這個問題都有幾個漏洞