Project: Add Checkstyle for code style enforcement

.github/workflows/checkstyle.yml

@@ -0,0 +1,21 @@
+name: Checkstyle
+
+on: [ pull_request ]
+
+jobs:
+  checkstyle:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up JDK 11
+        uses: actions/setup-java@v4
+        with:
+          java-version: '21'
+          distribution: 'adopt'
+      - name: Run Checkstyle
+        run: ./gradlew checkstyleMain checkstyleTest
+      - name: Upload Checkstyle results
+        uses: actions/upload-artifact@v4
+        with:
+          name: checkstyle-results
+          path: build/reports/checkstyle/

build.gradle

@@ -4,6 +4,20 @@ plugins {
     id 'org.springframework.boot' version '3.3.4'
     id 'io.spring.dependency-management' version '1.1.6'
     id 'org.flywaydb.flyway' version "10.18.0"
+    id 'checkstyle'
+}
+
+checkstyle {
+    toolVersion = "10.8.0"
+    configFile = file("config/checkstyle/checkstyle.xml")
+    maxWarnings = 0
+}
+
+tasks.withType(Checkstyle).configureEach {
+    reports {
+        xml.required = false
+        html.required = true
+    }
 }
 
 group = 'com.activecourses'

config/checkstyle/checkstyle.xml

@@ -0,0 +1,85 @@
+<?xml version="1.0"?>
+<!DOCTYPE module PUBLIC
+        "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
+        "https://checkstyle.org/dtds/configuration_1_3.dtd">
+
+<module name="Checker">
+    <property name="charset" value="UTF-8"/>
+    <property name="severity" value="warning"/>
+    <property name="fileExtensions" value="java, properties, xml"/>
+
+    <!-- Checks for whitespace -->
+    <module name="FileTabCharacter">
+        <property name="eachLine" value="true"/>
+    </module>
+
+    <module name="TreeWalker">
+        <!-- Checks for Naming Conventions -->
+        <module name="ConstantName"/>
+        <module name="LocalFinalVariableName"/>
+        <module name="LocalVariableName"/>
+        <module name="MemberName"/>
+        <module name="MethodName"/>
+        <module name="PackageName"/>
+        <module name="ParameterName"/>
+        <module name="StaticVariableName"/>
+        <module name="TypeName"/>
+
+        <!-- Checks for imports -->
+        <module name="AvoidStarImport"/>
+        <module name="IllegalImport"/>
+        <module name="RedundantImport"/>
+        <module name="UnusedImports"/>
+
+        <!-- Checks for Size Violations -->
+        <module name="MethodLength"/>
+        <module name="ParameterNumber"/>
+
+        <!-- Checks for whitespace -->
+        <module name="EmptyForIteratorPad"/>
+        <module name="GenericWhitespace"/>
+        <module name="MethodParamPad"/>
+        <module name="NoWhitespaceAfter"/>
+        <module name="NoWhitespaceBefore"/>
+        <module name="OperatorWrap"/>
+        <module name="ParenPad"/>
+        <module name="TypecastParenPad"/>
+        <module name="WhitespaceAfter"/>
+        <module name="WhitespaceAround"/>
+
+        <!-- Modifier Checks -->
+        <module name="ModifierOrder"/>
+        <module name="RedundantModifier"/>
+
+        <!-- Checks for blocks -->
+        <module name="AvoidNestedBlocks"/>
+        <module name="EmptyBlock"/>
+        <module name="LeftCurly"/>
+        <module name="NeedBraces"/>
+        <module name="RightCurly"/>
+
+        <!-- Checks for common coding problems -->
+        <module name="EmptyStatement"/>
+        <module name="EqualsHashCode"/>
+        <module name="IllegalInstantiation"/>
+        <module name="InnerAssignment"/>
+        <module name="MagicNumber"/>
+        <module name="MissingSwitchDefault"/>
+        <module name="MultipleVariableDeclarations"/>
+        <module name="SimplifyBooleanExpression"/>
+        <module name="SimplifyBooleanReturn"/>
+
+        <!-- Checks for class design -->
+        <module name="DesignForExtension"/>
+        <module name="FinalClass"/>
+        <module name="HideUtilityClassConstructor"/>
+        <module name="InterfaceIsType"/>
+        <module name="VisibilityModifier"/>
+
+        <!-- Miscellaneous other checks -->
+        <module name="ArrayTypeStyle"/>
+        <module name="FinalParameters"/>
+        <module name="TodoComment"/>
+        <module name="UpperEll"/>
+    </module>
+</module>