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Issue #461: Field single declaration check implemented
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‎eclipsecs-sevntu-plugin/src/com/github/sevntu/checkstyle/checks/coding/checkstyle-metadata.properties‎

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@@ -43,6 +43,10 @@ EmptyPublicCtorInClassCheck.desc = <p>This Check looks for useless empty public
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EmptyPublicCtorInClassCheck.classAnnotationNames = Regex which matches names of class annotations which require class to have public no-argument ctor. Default value is "javax\\.persistence\\.Entity".
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EmptyPublicCtorInClassCheck.ctorAnnotationNames = Regex which matches names of ctor annotations which make empty public ctor essential. Default value is "com\\.google\\.inject\\.Inject".
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FieldSingleDeclarationCheck.name = Field Single Declaration Check
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FieldSingleDeclarationCheck.desc = <p>This checks ensures that classes have at most 1 field of the given className. This can be useful for example to ensure that only one Logger is used.</p>
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FieldSingleDeclarationCheck.fullyQualifiedClassName = Fully qualified name of class of which there should only be max. 1 field per class. Example: "org.slf4j.Logger".
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FinalizeImplementationCheck.name = Finalize Implementation
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FinalizeImplementationCheck.desc = <p>This Check detects 3 most common cases of incorrect finalize() method implementation:</p><ul><li>negates effect of superclass finalize<br/><code>protected void finalize() { } <br/> protected void finalize() { doSomething(); }</code></li><li>useless (or worse) finalize<br/><code>protected void finalize() { super.finalize(); }</code></li><li>public finalize<br/><code>public void finalize() { try { doSomething(); } finally { super.finalize() } }</code></li></ul>
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‎eclipsecs-sevntu-plugin/src/com/github/sevntu/checkstyle/checks/coding/checkstyle-metadata.xml‎

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@@ -162,6 +162,17 @@
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<message-key key="empty.public.ctor"/>
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</rule-metadata>
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<rule-metadata name="%FieldSingleDeclarationCheck.name" internal-name="FieldSingleDeclarationCheck" parent="TreeWalker">
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<alternative-name internal-name="com.github.sevntu.checkstyle.checks.coding.FieldSingleDeclarationCheck"/>
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<description>%FieldSingleDeclarationCheck.desc</description>
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<property-metadata name="fullyQualifiedClassName" datatype="String" default-value="java.util.logging.Logger">
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<description>%FieldSingleDeclarationCheck.fullyQualifiedClassName</description>
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</property-metadata>
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<message-key key="field.count"/>
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</rule-metadata>
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<rule-metadata name="%ForbidCertainImportsCheck.name" internal-name="ForbidCertainImportsCheck" parent="TreeWalker">
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<alternative-name internal-name="com.github.sevntu.checkstyle.checks.coding.ForbidCertainImportsCheck"/>
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<description>%ForbidCertainImportsCheck.desc</description>

‎sevntu-checks/sevntu-checks.xml‎

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@@ -152,6 +152,9 @@
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<property name="ignoreFieldNamePattern" value="serialVersionUID"/>
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</module>
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<module name="com.github.sevntu.checkstyle.checks.coding.EmptyPublicCtorInClassCheck"/>
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<module name="com.github.sevntu.checkstyle.checks.coding.FieldSingleDeclarationCheck">
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<property name="fullyQualifiedClassName" value="java.util.logging.Logger"/>
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</module>
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<module name="com.github.sevntu.checkstyle.checks.coding.DiamondOperatorForVariableDefinitionCheck"/>
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<module name="com.github.sevntu.checkstyle.checks.coding.NameConventionForJunit4TestClassesCheck"/>
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<module name="com.github.sevntu.checkstyle.checks.coding.UselessSuperCtorCallCheck"/>

‎sevntu-checks/src/main/java/com/github/sevntu/checkstyle/SevntuUtil.java‎

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@@ -21,6 +21,9 @@
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import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
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import com.puppycrawl.tools.checkstyle.api.DetailAST;
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import com.puppycrawl.tools.checkstyle.api.FullIdent;
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import com.puppycrawl.tools.checkstyle.api.TokenTypes;
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import com.puppycrawl.tools.checkstyle.utils.CheckUtil;
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import com.puppycrawl.tools.checkstyle.utils.TokenUtil;
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/**
@@ -76,4 +79,40 @@ public static DetailAST getNextSubTreeNode(DetailAST node, DetailAST subTreeRoot
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return toVisitAst;
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}
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/**
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* Obtains full type name of first token in node.
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* @param ast an AST node
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* @return fully qualified name (FQN) of type, or null if none was found
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*/
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public static String getTypeNameOfFirstToken(DetailAST ast) {
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final DetailAST findFirstToken = ast.findFirstToken(TokenTypes.TYPE);
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final FullIdent ident = CheckUtil.createFullType(findFirstToken);
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return ident.getText();
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}
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/**
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* Checks node for matching class, taken both FQN and short name into account.
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*
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* @param ast
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* an AST node
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* @param fqClassName
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* fully qualified class name
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* @return true if type name of first token in node is fqnClassName, or its short name; false
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* otherwise
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*/
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public static boolean matchesFullyQualifiedName(DetailAST ast, String fqClassName) {
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final String typeName = getTypeNameOfFirstToken(ast);
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final int lastDotPosition = fqClassName.lastIndexOf('.');
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boolean isMatched = false;
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if (lastDotPosition == -1) {
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isMatched = typeName.equals(fqClassName);
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}
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else {
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final String shortClassName = fqClassName.substring(lastDotPosition + 1);
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isMatched = typeName.equals(fqClassName) || typeName.equals(shortClassName);
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}
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return isMatched;
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}
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}

‎sevntu-checks/src/main/java/com/github/sevntu/checkstyle/checks/coding/FieldSingleDeclarationCheck.java‎

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////////////////////////////////////////////////////////////////////////////////
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// checkstyle: Checks Java source code for adherence to a set of rules.
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// Copyright (C) 2001-2020 the original author or authors.
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public
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// License as published by the Free Software Foundation; either
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// version 2.1 of the License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License along with this library; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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////////////////////////////////////////////////////////////////////////////////
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package com.github.sevntu.checkstyle.checks.coding;
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import com.github.sevntu.checkstyle.SevntuUtil;
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import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
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import com.puppycrawl.tools.checkstyle.api.DetailAST;
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import com.puppycrawl.tools.checkstyle.api.TokenTypes;
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/**
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* <p>This checks ensures that classes have at most 1 field of the given className.</p>
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*
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* <p>This can be useful for example to ensure that only one Logger is used:</p>
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*
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* <pre>
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* &lt;module name="TreeWalker"&gt;
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* &lt;module name="com.github.sevntu.checkstyle.checks.coding.FieldSingleDeclarationCheck"&gt;
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* &lt;property name="fullyQualifiedClassName" value="org.slf4j.Logger" /&gt;
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* &lt;/module&gt;
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* &lt;/module&gt;
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*
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* class Example {
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* private static final org.slf4j.Logger logger = LoggerFactory.getLogger(Example.class); // OK
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* private static org.slf4j.Logger logger2; // NOK!
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* }
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* </pre>
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*
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* @author Milos Fabian, Pantheon Technologies - original author (in OpenDaylight.org)
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* @author Michael Vorburger.ch - refactored and made more generalized for contribution to Sevntu
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* @author <a href="mailto:[email protected]">Yasser Aziza</a> - completed sevntu integration
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*/
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public class FieldSingleDeclarationCheck extends AbstractCheck {
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/**
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* Violation message key.
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*/
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public static final String MSG_KEY = "field.count";
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/**
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* Configuration property with class name check for.
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*/
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private String fullyQualifiedClassName = "java.util.logging.Logger";
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/**
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* Field to remember if class was previously seen in current File.
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*/
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private boolean hasPreviouslySeenClass;
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/**
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* Set Class of which there should only be max. 1 field per class.
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* @param className the fully qualified name (FQN) of the class
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*/
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public void setFullyQualifiedClassName(String className) {
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this.fullyQualifiedClassName = className;
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}
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@Override
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public int[] getDefaultTokens() {
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return new int[] {TokenTypes.VARIABLE_DEF };
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}
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@Override
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public int[] getRequiredTokens() {
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return getDefaultTokens();
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}
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@Override
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public int[] getAcceptableTokens() {
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return getDefaultTokens();
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}
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@Override
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public void beginTree(DetailAST rootAST) {
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this.hasPreviouslySeenClass = false;
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}
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@Override
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public void visitToken(DetailAST ast) {
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if (SevntuUtil.matchesFullyQualifiedName(ast, fullyQualifiedClassName)) {
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if (hasPreviouslySeenClass) {
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log(ast.getLineNo(), MSG_KEY, fullyQualifiedClassName);
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}
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this.hasPreviouslySeenClass = true;
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}
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}
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}

‎sevntu-checks/src/main/resources/com/github/sevntu/checkstyle/checks/coding/messages.properties‎

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@@ -14,6 +14,7 @@ custom.declaration.order.method=Method definition in wrong order. Expected ''{0}
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diamond.operator.for.variable.definition=Diamond operator expected.
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either.log.or.throw=Either log or throw exception.
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empty.public.ctor=This empty public constructor is useless.
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field.count={0} should be declared only once.
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finalize.implementation.missed.super.finalize=You have to call super.finalize() right after finally opening brace.
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finalize.implementation.missed.try.finally=finalize() method should contain try-finally block with super.finalize() call inside finally block.
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finalize.implementation.public=finalize() method should have a "protected" visibility.

‎sevntu-checks/src/test/java/com/github/sevntu/checkstyle/checks/coding/FieldSingleDeclarationCheckTest.java‎

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////////////////////////////////////////////////////////////////////////////////
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// checkstyle: Checks Java source code for adherence to a set of rules.
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// Copyright (C) 2001-2020 the original author or authors.
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public
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// License as published by the Free Software Foundation; either
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// version 2.1 of the License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License along with this library; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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////////////////////////////////////////////////////////////////////////////////
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package com.github.sevntu.checkstyle.checks.coding;
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import org.junit.Test;
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import com.puppycrawl.tools.checkstyle.AbstractModuleTestSupport;
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import com.puppycrawl.tools.checkstyle.DefaultConfiguration;
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/**
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* LoggerDeclarationsCountCheck test.
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*
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* @author <a href="mailto:[email protected]">Michael Vorburger</a> - completed sevntu integration
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*/
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public class FieldSingleDeclarationCheckTest extends AbstractModuleTestSupport {
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@Override
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protected String getPackageLocation() {
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return "com/github/sevntu/checkstyle/checks/coding";
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}
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@Test
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public void testFieldSingleDeclarationOk() throws Exception {
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final DefaultConfiguration checkConfig =
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createModuleConfig(FieldSingleDeclarationCheck.class);
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checkConfig.addAttribute("fullyQualifiedClassName", "org.slf4j.Logger");
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verify(checkConfig, getPath("InputFieldSingleDeclarationCheckOk.java"), new String[] {});
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}
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@Test
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public void testFieldSingleDeclarationNok() throws Exception {
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final DefaultConfiguration checkConfig =
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createModuleConfig(FieldSingleDeclarationCheck.class);
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checkConfig.addAttribute("fullyQualifiedClassName", "org.slf4j.Logger");
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final String[] expected = {
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"10: " + getCheckMessage(FieldSingleDeclarationCheck.MSG_KEY, "org.slf4j.Logger"),
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};
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verify(checkConfig, getPath("InputFieldSingleDeclarationCheckNok.java"), expected);
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verify(checkConfig, getPath("InputFieldSingleDeclarationCheckOk.java"), new String[] {});
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}
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@Test
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public void testFieldSingleDeclarationFqnNok() throws Exception {
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final DefaultConfiguration checkConfig =
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createModuleConfig(FieldSingleDeclarationCheck.class);
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checkConfig.addAttribute("fullyQualifiedClassName", "org.slf4j.Logger");
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final String[] expected = {
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"7: " + getCheckMessage(FieldSingleDeclarationCheck.MSG_KEY, "org.slf4j.Logger"),
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};
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verify(checkConfig, getPath("InputFieldSingleDeclarationCheckFqnNok.java"), expected);
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verify(checkConfig, getPath("InputFieldSingleDeclarationCheckOk.java"), new String[] {});
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}
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@Test
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public void testNoClassNameConfigured() throws Exception {
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final DefaultConfiguration checkConfig =
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createModuleConfig(FieldSingleDeclarationCheck.class);
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verify(checkConfig, getPath("InputFieldSingleDeclarationCheckOk.java"), new String[] {});
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verify(checkConfig, getPath("InputFieldSingleDeclarationCheckNok.java"), new String[] {});
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verify(checkConfig, getPath("InputFieldSingleDeclarationCheckFqnNok.java"),
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new String[] {});
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}
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@Test
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public void testCustomTokens() throws Exception {
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final DefaultConfiguration checkConfig =
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createModuleConfig(FieldSingleDeclarationCheck.class);
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checkConfig.addAttribute("fullyQualifiedClassName", "org.slf4j.Logger");
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// This is required just so that getAcceptableTokens() gets coverage
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checkConfig.addAttribute("tokens", "VARIABLE_DEF");
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verify(checkConfig, getPath("InputFieldSingleDeclarationCheckOk.java"), new String[] {});
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}
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@Test
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public void testUnknownClassName() throws Exception {
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final DefaultConfiguration checkConfig =
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createModuleConfig(FieldSingleDeclarationCheck.class);
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checkConfig.addAttribute("fullyQualifiedClassName", "SomeClass");
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// This is required just so that getAcceptableTokens() gets coverage
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checkConfig.addAttribute("tokens", "VARIABLE_DEF");
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verify(checkConfig, getPath("InputFieldSingleDeclarationCheckOk.java"), new String[] {});
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verify(checkConfig, getPath("InputFieldSingleDeclarationCheckNok.java"), new String[] {});
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verify(checkConfig, getPath("InputFieldSingleDeclarationCheckFqnNok.java"),
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new String[] {});
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}
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}

‎sevntu-checks/src/test/resources/com/github/sevntu/checkstyle/checks/coding/InputFieldSingleDeclarationCheckFqnNok.java‎

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package com.github.sevntu.checkstyle.checks.coding;
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public class InputFieldSingleDeclarationCheckFqnNok {
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// even twice a FQN type names work:
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org.slf4j.Logger logger1;
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org.slf4j.Logger logger2; // <= Checkstyle violation raised here!
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}

‎sevntu-checks/src/test/resources/com/github/sevntu/checkstyle/checks/coding/InputFieldSingleDeclarationCheckNok.java‎

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package com.github.sevntu.checkstyle.checks.coding;
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import java.io.File;
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import java.util.logging.Logger;
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public class InputFieldSingleDeclarationCheckNok {
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// both FQN and import'ed type names work:
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Logger logger1;
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org.slf4j.Logger logger2; // <= Checkstyle violation raised here!
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// some field of another type (req. for test coverage)
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File file;
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// a method, so that there are not only fields here (req. for test coverage)
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void foo() { }
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}

‎sevntu-checks/src/test/resources/com/github/sevntu/checkstyle/checks/coding/InputFieldSingleDeclarationCheckOk.java‎

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package com.github.sevntu.checkstyle.checks.coding;
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public class InputFieldSingleDeclarationCheckOk {
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org.slf4j.Logger logger;
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}

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