Format and Check Code Style

I want to match the coding style with Google Java Style Guide. I like to press Reformat Code button to auto format the current java file. And I need the CheckStyle plugin to help me check the style.

Google Java Style Guide

import XML file of Google Java style

• download the XML from styleguide/intellij-java-google-style.xml of Google's GitHub
• go to Preferences
• go to Editor
• go to Code Style
• click the Manage button (which is right of Scheme text)
• click the Import button
• chose import from Intelljj IDEA code style XML
• select theintellij-java-google-style.xml file
• click the Apply button

Now, I can open any Java class file, and press Reformat Code (Alt + Command + L) to auto format it to Google Java style.

intellij-java-google-style.xml

install CheckStyle-IDEA plugin

• go to Preferences
• go to Plugins
• type CheckStyle-IDEA into search field
• press Browse repositories
• click the Install button of CheckStyle-IDEA plugin (version 5.10.1)
• restart Android Studio
• go to Other Settings in Preferences
• At Checkstyle page, set Google Checks bundled to be active
• Select the Scan Scope to be All files in project

Now, I can open Java class file, and press Check Current File button to analyse coding style.

Checkstyle found 165 item(s) in 1 file(s)

Google's Java Style Checkstyle Coverage

create Gradle task for check style

• download thegoogle_checks.xml to ${rootProject}/qualityTools/checkStyle.xml
• create ${rootProject}/qualityTools/quality.gradle file

apply plugin: 'checkstyle'

task checkstyle(type: Checkstyle) {
    description 'check code standard'
    group 'verification'

    configFile rootProject.file('qualityTools/checkStyle.xml')

    source 'src/main/java'
    include '**/*.java'
    exclude '**/gen/**'
    exclude '**/R.java'
    exclude '**/BuildConfig.java'

    classpath = files()
}

checkstyle {
    toolVersion '8.2'
    ignoreFailures = false
    showViolations = true
}

• apply Gradle config to root build.gradle

apply from: 'config/dependencies.gradle'

buildscript {
    repositories {
        jcenter()
    }

    dependencies {
        classpath 'com.android.tools.build:gradle:2.3.3'
        classpath 'me.tatarka:gradle-retrolambda:3.2.5'
    }
}

allprojects {
    repositories {
        jcenter()
    }

    ext {
        compatibility = JavaVersion.VERSION_1_8
        ...
    }

    apply from: rootProject.file('qualityTools/quality.gradle')
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

Now, I can find the checkstyle task on each module's verification tasks group. I run the checkstyle task on root module, then I can find the report HTML and XML files in build/reports folder of each modules.

/Users/HSY/Desktop/${projectName}/app/build/reports/checkstyle/checkstyle.html

CheckStyle Audit
Designed for use with CheckStyle and Ant.
------------------------------------------
Summary
Files    Errors
116    9465

checkstyle/src/main/resources/google_checks.xml

CheckStyle and Google style XML version is not matched issue

:app:checkstyle FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:checkstyle'.
> Unable to create a Checker: Property 'fileExtensions' in module Checker does not exist, please check the documentation

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

BUILD FAILED

Total time: 1.911 secs

The CheckStyle version is not matched. I have to specified its version to the latest one.

checkstyle {
    toolVersion '8.2'
}

Property does not exist error in checkstyle configuration file of Stack Overflow

check style on Git pre-commit

Install Groovy