add checkstyle (fixes #15)

.github/workflows/release.yml

@@ -10,7 +10,7 @@ jobs:
           distribution: "temurin"
           java-version: 17
       - uses: gradle/wrapper-validation-action@v1
-      - run: ./gradlew build publish --stacktrace
+      - run: ./gradlew build checkstyleMain publish --stacktrace
         env:
           MAVEN_URL: ${{ secrets.MAVEN_URL }}
           MAVEN_USERNAME: ${{ secrets.MAVEN_USERNAME }}

.github/workflows/test.yml

@@ -14,4 +14,4 @@ jobs:
           distribution: "temurin"
           java-version: ${{ matrix.java }}
       - uses: gradle/wrapper-validation-action@v1
-      - run: ./gradlew build test publishToMavenLocal --stacktrace
+      - run: ./gradlew build checkstyleMain test publishToMavenLocal --stacktrace

build.gradle

@@ -1,6 +1,7 @@
 plugins {
 	id 'java'
 	id 'maven-publish'
+	id 'checkstyle'
 	id 'org.quiltmc.gradle.licenser' version '1.+'
 }
 

config/checkstyle/checkstyle.xml

@@ -0,0 +1,167 @@
+<?xml version="1.0"?>
+<!DOCTYPE module PUBLIC "-//Puppy Crawl//DTD Check Configuration 1.2//EN" "http://www.puppycrawl.com/dtds/configuration_1_2.dtd">
+<module name="Checker">
+	<property name="charset" value="UTF-8"/>
+	<property name="fileExtensions" value="java"/>
+	<property name="localeLanguage" value="en"/>
+	<property name="localeCountry" value="US"/>
+	<property name="tabWidth" value="4"/>
+
+	<module name="NewlineAtEndOfFile"/>
+
+	<!-- disallow trailing whitespace -->
+	<module name="RegexpSingleline">
+		<property name="format" value="\s+$"/>
+		<property name="message" value="trailing whitespace"/>
+	</module>
+
+	<!-- note: RegexpMultiline shows nicer messages than Regexp, but has to be outside TreeWalker -->
+	<!-- disallow multiple consecutive blank lines -->
+	<module name="RegexpMultiline">
+		<property name="format" value="\n[\t ]*\r?\n[\t ]*\r?\n"/>
+		<property name="message" value="adjacent blank lines"/>
+	</module>
+
+	<!-- disallow blank after { -->
+	<module name="RegexpMultiline">
+		<property name="format" value="\{[\t ]*\r?\n[\t ]*\r?\n"/>
+		<property name="message" value="blank line after '{'"/>
+	</module>
+
+	<!-- disallow blank before } -->
+	<module name="RegexpMultiline">
+		<property name="format" value="\n[\t ]*\r?\n[\t ]*\}"/>
+		<property name="message" value="blank line before '}'"/>
+	</module>
+
+	<!-- require blank after } in the same indentation level -->
+	<module name="RegexpMultiline">
+		<!-- \n<indentation>}\n<same indentation><whatever unless newline, '}' or starting with cas(e) or def(ault)> -->
+		<property name="format" value="(?&lt;=\n)([\t]+)\}\r?\n\1(?:[^\r\n\}cd]|c[^\r\na]|ca[^\r\ns]|d[^\r\ne]|de[^\r\nf])"/>
+		<property name="message" value="missing blank line after block at same indentation level"/>
+	</module>
+
+	<module name="TreeWalker">
+		<!-- Allow "//CHECKSTYLE.OFF: <InspectionName>" and "//CHECKSTYLE.ON: <InspectionName>" pairs to toggle some inspections -->
+		<module name="SuppressionCommentFilter">
+			<property name="offCommentFormat" value="CHECKSTYLE.OFF\: ([\w\|]+)"/>
+			<property name="onCommentFormat" value="CHECKSTYLE.ON\: ([\w\|]+)"/>
+			<property name="checkFormat" value="$1"/>
+		</module>
+
+		<!-- Ensure all imports are ship shape -->
+		<module name="AvoidStarImport">
+			<property name="excludes" value="org.hamcrest.Matchers"/>
+		</module>
+		<module name="IllegalImport"/>
+		<module name="RedundantImport"/>
+		<module name="UnusedImports"/>
+
+		<module name="ImportOrder">
+			<property name="groups" value="*,/java|javax/"/>
+			<property name="ordered" value="false"/><!-- the plugin orders alphabetically without considering separators.. -->
+			<property name="separated" value="true"/>
+			<property name="option" value="bottom"/>
+			<property name="sortStaticImportsAlphabetically" value="true"/>
+		</module>
+
+		<!-- Ensures braces are at the end of a line -->
+		<module name="LeftCurly"/>
+		<module name="RightCurly"/>
+
+		<!-- single line statements on one line, -->
+		<module name="NeedBraces">
+			<property name="tokens" value="LITERAL_IF,LITERAL_FOR,LITERAL_WHILE"/>
+			<property name="allowSingleLineStatement" value="true"/>
+		</module>
+		<module name="NeedBraces">
+			<property name="tokens" value="LITERAL_ELSE,LITERAL_DO"/>
+			<property name="allowSingleLineStatement" value="false"/>
+		</module>
+
+		<module name="EmptyLineSeparator">
+			<property name="allowNoEmptyLineBetweenFields" value="true"/>
+			<property name="allowMultipleEmptyLines" value="false"/>
+			<!-- exclude  METHOD_DEF and VARIABLE_DEF -->
+			<property name="tokens" value="PACKAGE_DEF,IMPORT,STATIC_IMPORT,CLASS_DEF,INTERFACE_DEF,ENUM_DEF,STATIC_INIT,INSTANCE_INIT,CTOR_DEF"/>
+		</module>
+
+		<module name="OperatorWrap"/>
+		<module name="SeparatorWrap">
+			<property name="tokens" value="DOT,ELLIPSIS,AT"/>
+			<property name="option" value="nl"/>
+		</module>
+		<module name="SeparatorWrap">
+			<property name="tokens" value="COMMA,SEMI"/>
+			<property name="option" value="eol"/>
+		</module>
+
+		<module name="Indentation">
+			<property name="basicOffset" value="4"/>
+			<property name="caseIndent" value="4"/>
+			<property name="throwsIndent" value="4"/>
+			<property name="arrayInitIndent" value="4"/>
+			<property name="lineWrappingIndentation" value="8"/>
+		</module>
+
+		<module name="ParenPad"/>
+		<module name="NoWhitespaceBefore"/>
+		<module name="NoWhitespaceAfter">
+			<!-- allow ARRAY_INIT -->
+			<property name="tokens" value="AT,INC,DEC,UNARY_MINUS,UNARY_PLUS,BNOT,LNOT,DOT,ARRAY_DECLARATOR,INDEX_OP"/>
+		</module>
+		<module name="WhitespaceAfter"/>
+		<module name="WhitespaceAround">
+			<!-- Allow PLUS, MINUS, MUL, DIV as they may be more readable without spaces in some cases -->
+			<property name="tokens" value="ASSIGN,BAND,BAND_ASSIGN,BOR,BOR_ASSIGN,BSR,BSR_ASSIGN,BXOR,BXOR_ASSIGN,COLON,DIV_ASSIGN,DO_WHILE,EQUAL,GE,GT,LAMBDA,LAND,LCURLY,LE,LITERAL_CATCH,LITERAL_DO,LITERAL_ELSE,LITERAL_FINALLY,LITERAL_FOR,LITERAL_IF,LITERAL_RETURN,LITERAL_SWITCH,LITERAL_SYNCHRONIZED,LITERAL_TRY,LITERAL_WHILE,LOR,LT,MINUS_ASSIGN,MOD,MOD_ASSIGN,NOT_EQUAL,PLUS_ASSIGN,QUESTION,RCURLY,SL,SLIST,SL_ASSIGN,SR,SR_ASSIGN,STAR,STAR_ASSIGN,LITERAL_ASSERT,TYPE_EXTENSION_AND"/>
+
+			<property name="allowEmptyConstructors" value="true" />
+			<property name="allowEmptyMethods" value="true" />
+			<property name="allowEmptyTypes" value="true" />
+			<property name="allowEmptyLoops" value="true" />
+			<property name="allowEmptyLambdas" value="true" />
+		</module>
+		<module name="SingleSpaceSeparator"/>
+		<module name="GenericWhitespace"/>
+		<module name="CommentsIndentation"/>
+
+		<module name="ArrayTypeStyle"/>
+		<module name="DefaultComesLast">
+			<property name="skipIfLastAndSharedWithCase" value="true"/>
+		</module>
+		<module name="SimplifyBooleanExpression"/>
+		<module name="SimplifyBooleanReturn"/>
+		<module name="StringLiteralEquality"/>
+
+		<module name="ModifierOrder"/>
+		<module name="RedundantModifier"/>
+
+		<module name="AnnotationLocation"/>
+		<module name="MissingOverride"/>
+
+		<!-- By default this allows catch blocks with only comments -->
+		<module name="EmptyCatchBlock"/>
+
+		<!-- Require the use of the "this" keyword -->
+		<module name="RequireThis">
+			<property name="validateOnlyOverlapping" value="false"/>
+		</module>
+
+		<!-- Enforce tabs -->
+		<module name="RegexpSinglelineJava">
+			<property name="format" value="^\t* ([^*]|\*[^ /])"/>
+			<property name="message" value="non-tab indentation"/>
+		</module>
+
+		<module name="OuterTypeFilename"/>
+		<module name="PackageDeclaration"/>
+
+		<!--<module name="InvalidJavadocPosition"/>-->
+		<module name="JavadocParagraph">
+			<property name="allowNewlineParagraph" value="false"/>
+		</module>
+		<module name="AtclauseOrder">
+			<property name="tagOrder" value="@param,@return,@throws,@deprecated"/>
+		</module>
+	</module>
+</module>

src/main/java/org/quiltmc/config/api/Config.java

@@ -21,7 +21,11 @@
 import org.quiltmc.config.api.metadata.MetadataContainer;
 import org.quiltmc.config.api.metadata.MetadataContainerBuilder;
 import org.quiltmc.config.api.metadata.MetadataType;
-import org.quiltmc.config.api.values.*;
+import org.quiltmc.config.api.values.TrackedValue;
+import org.quiltmc.config.api.values.ValueKey;
+import org.quiltmc.config.api.values.ValueList;
+import org.quiltmc.config.api.values.ValueMap;
+import org.quiltmc.config.api.values.ValueTreeNode;
 import org.quiltmc.config.impl.ConfigImpl;
 
 import java.nio.file.Path;
@@ -106,7 +110,6 @@ public interface Config extends MetadataContainer {
 	 *     <li>ValueTreeNode.Section("gui")</li>
 	 *     <li>TrackedValue("count", 100)</li>
 	 * </ul>
-	 *
 	 * iterating over children would need to be done by checking <pre>node instanceof ValueTreeNode.Section</pre>
 	 * and iterating over that node as well, recursively.
 	 */
@@ -402,21 +405,19 @@ interface Creator {
 		void create(Builder builder);
 	}
 
-
 	/**
 	 * @deprecated for removal; use {@link ReflectiveConfig.Section}
 	 */
 	@Deprecated
 	interface Section {
-
 	}
 
 	@ApiStatus.NonExtendable
 	interface Builder extends SectionBuilder {
 		/**
-		 * Adds a value to this config file
+		 * Adds a value to this config file.
 		 *
-		 * A field should be either:
+		 * <p>A field should be either:
 		 * <ul>
 		 *     <li>A basic type ({@link Integer}, {@link Long}, {@link Float}, {@link Double}, {@link Boolean}, {@link String}, or enum)</li>
 		 *     <li>A complex type (a {@link ValueList} or {@link ValueMap} of basic or complex types)</li>
@@ -433,7 +434,7 @@ interface Builder extends SectionBuilder {
 		Builder section(String key, Consumer<SectionBuilder> creator);
 
 		/**
-		 * Create or configure a piece of metadata
+		 * Create or configure a piece of metadata.
 		 *
 		 * @param type the type of metadata to configure
 		 * @param builderConsumer the modifications to be made to the piece of metadata
@@ -442,17 +443,17 @@ interface Builder extends SectionBuilder {
 		<M, B extends MetadataType.Builder<M>> Builder metadata(MetadataType<M, B> type, Consumer<B> builderConsumer);
 
 		/**
-		 * Adds a default listener to the resulting {@link Config} that's called whenever any of its values updated
+		 * Adds a default listener to the resulting {@link Config} that's called whenever any of its values updated.
 		 *
 		 * @param callback an update listener
 		 * @return this
 		 */
 		Builder callback(UpdateCallback callback);
 
 		/**
-		 * Sets the default file type for the config file this config will be saved to
+		 * Sets the default file type for the config file this config will be saved to.
 		 *
-		 * Note that this can be overridden by the end user with a launch parameter
+		 * <p>Note that this can be overridden by the end user with a launch parameter
 		 *
 		 * @return this
 		 */
@@ -462,9 +463,9 @@ interface Builder extends SectionBuilder {
 	@ApiStatus.NonExtendable
 	interface SectionBuilder extends MetadataContainerBuilder<SectionBuilder> {
 		/**
-		 * Adds a value to this config file
+		 * Adds a value to this config file.
 		 *
-		 * A field should be either:
+		 * <p>A field should be either:
 		 * <ul>
 		 *     <li>A basic type ({@link Integer}, {@link Long}, {@link Float}, {@link Double}, {@link Boolean}, {@link String}, or enum)</li>
 		 *     <li>A complex type (a {@link ValueList} or {@link ValueMap} of basic or complex types)</li>

src/main/java/org/quiltmc/config/api/Constraint.java

@@ -69,7 +69,7 @@ static Constraint<String> matching(String regex) {
 
 			@Override
 			public Optional<String> test(String value) {
-				if (pattern.matcher(value).matches()) {
+				if (this.pattern.matcher(value).matches()) {
 					return Optional.empty();
 				} else {
 					return Optional.of(String.format("Value '%s' does not match pattern '%s'", value, regex));

src/main/java/org/quiltmc/config/api/ReflectiveConfig.java

@@ -105,7 +105,7 @@ public final <T> TrackedValue<T> value(T defaultValue) {
 
 	@SafeVarargs
 	public final <T> TrackedValue<ValueList<T>> list(T defaultValue, T... values) {
-		return value(ValueList.create(defaultValue, values));
+		return this.value(ValueList.create(defaultValue, values));
 	}
 
 	public final <T> ValueMap.TrackedBuilder<T> map(T defaultValue) {
@@ -121,7 +121,7 @@ public final <T> TrackedValue<T> value(T defaultValue) {
 
 		@SafeVarargs
 		public final <T> TrackedValue<ValueList<T>> list(T defaultValue, T... values) {
-			return value(ValueList.create(defaultValue, values));
+			return this.value(ValueList.create(defaultValue, values));
 		}
 
 		public final <T> ValueMap.TrackedBuilder<T> map(T defaultValue) {

src/main/java/org/quiltmc/config/api/WrappedConfig.java

@@ -24,7 +24,6 @@
 import java.nio.file.Path;
 import java.util.Map;
 
-
 /**
  * @deprecated for removal: use {@link ReflectiveConfig} instead.
  */

src/main/java/org/quiltmc/config/api/annotations/Alias.java

@@ -51,7 +51,7 @@
 	final class Builder implements MetadataType.Builder<Aliases> {
 		private final List<String> aliases = new ArrayList<>(0);
 
-		public Builder() {
+		Builder() {
 		}
 
 		public void add(String... aliases) {

src/main/java/org/quiltmc/config/api/annotations/Comment.java

@@ -21,8 +21,16 @@
 import org.quiltmc.config.api.metadata.MetadataType;
 import org.quiltmc.config.impl.CommentsImpl;
 
-import java.lang.annotation.*;
-import java.util.*;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Repeatable;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.Optional;
 
 /**
  * Used to annotate fields of classes that represent config files with comments that can be saved to disk or displayed
@@ -41,7 +49,7 @@
 	final class Builder implements MetadataType.Builder<Comments> {
 		private final List<String> comments = new ArrayList<>(0);
 
-		public Builder() {
+		Builder() {
 		}
 
 		public void add(String... comments) {

src/main/java/org/quiltmc/config/api/annotations/ConfigFieldAnnotationProcessor.java

@@ -21,7 +21,6 @@
 import org.quiltmc.config.impl.ConfigFieldAnnotationProcessors;
 
 import java.lang.annotation.Annotation;
-import java.util.Collections;
 
 /**
  * Converts data in an annotation on a field to metadata on a {@link TrackedValue}.
@@ -33,7 +32,6 @@ public interface ConfigFieldAnnotationProcessor<T extends Annotation> {
 
 	static <T extends Annotation> void register(Class<T> annotationClass, ConfigFieldAnnotationProcessor<T> processor) {
 		ConfigFieldAnnotationProcessors.register(annotationClass, processor);
-
 	}
 
 	static void applyAnnotationProcessors(Annotation annotation, MetadataContainerBuilder<?> builder) {

src/main/java/org/quiltmc/config/api/annotations/Processor.java

@@ -34,7 +34,6 @@
  * </ul>
  *
  * <h3>Examples:</h3>
- *
  * Tracked value:
  * <pre>
  * {@code
@@ -47,7 +46,7 @@
  * }
  * </pre>
  *
- * Config class:
+ * <p>Config class:
  * <pre>
  * {@code
  * @Processor("processConfig")
@@ -59,7 +58,7 @@
  * }
  * </pre>
  *
- * Section:
+ * <p>Section:
  * <pre>
  * {@code
  * @Processor("processCoolSection")