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Anmol202005Anmol202005
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Issue #33: FinalLocalVariable recipe created
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‎src/main/java/org/checkstyle/autofix/recipe/FinalLocalVariable.java

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///////////////////////////////////////////////////////////////////////////////////////////////
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// checkstyle-openrewrite-recipes: Automatically fix Checkstyle violations with OpenRewrite.
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// Copyright (C) 2025 The Checkstyle OpenRewrite Recipes Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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///////////////////////////////////////////////////////////////////////////////////////////////
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package org.checkstyle.autofix.recipe;
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import java.nio.file.Path;
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import java.util.ArrayList;
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import java.util.List;
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import java.util.concurrent.CancellationException;
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import java.util.function.Function;
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import org.checkstyle.autofix.parser.CheckstyleViolation;
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import org.openrewrite.Cursor;
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import org.openrewrite.ExecutionContext;
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import org.openrewrite.PrintOutputCapture;
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import org.openrewrite.Recipe;
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import org.openrewrite.Tree;
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import org.openrewrite.TreeVisitor;
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import org.openrewrite.internal.RecipeRunException;
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import org.openrewrite.java.JavaIsoVisitor;
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import org.openrewrite.java.tree.J;
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import org.openrewrite.java.tree.Space;
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import org.openrewrite.marker.Markers;
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/**
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* Fixes Checkstyle FinalLocalVariable violations by adding 'final' modifier to local variables
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* that are never reassigned.
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*/
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public class FinalLocalVariable extends Recipe {
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private final List<CheckstyleViolation> violations;
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public FinalLocalVariable(List<CheckstyleViolation> violations) {
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this.violations = violations;
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}
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@Override
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public String getDisplayName() {
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return "FinalLocalVariable recipe";
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}
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@Override
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public String getDescription() {
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return "Adds 'final' modifier to local variables that never have their values changed.";
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}
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@Override
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public TreeVisitor<?, ExecutionContext> getVisitor() {
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return new LocalVariableVisitor();
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}
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private final class LocalVariableVisitor extends JavaIsoVisitor<ExecutionContext> {
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private Path sourcePath;
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@Override
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public J.CompilationUnit visitCompilationUnit(J.CompilationUnit cu, ExecutionContext ctx) {
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this.sourcePath = cu.getSourcePath();
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return super.visitCompilationUnit(cu, ctx);
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}
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@Override
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public J.VariableDeclarations visitVariableDeclarations(
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J.VariableDeclarations multiVariable, ExecutionContext ctx) {
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J.VariableDeclarations declarations = super.visitVariableDeclarations(multiVariable,
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ctx);
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if (!(getCursor().getParentTreeCursor().getValue() instanceof J.ClassDeclaration)
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&& declarations.getVariables().size() == 1) {
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final J.VariableDeclarations.NamedVariable variable = declarations
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.getVariables().get(0);
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if (isAtViolationLocation(variable)) {
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final List<J.Modifier> modifiers = new ArrayList<>();
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modifiers.add(new J.Modifier(Tree.randomId(), Space.EMPTY,
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Markers.EMPTY, null, J.Modifier.Type.Final, new ArrayList<>()));
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modifiers.addAll(Space.formatFirstPrefix(declarations.getModifiers(),
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Space.SINGLE_SPACE));
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declarations = declarations.withModifiers(modifiers)
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.withTypeExpression(declarations.getTypeExpression()
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.withPrefix(Space.SINGLE_SPACE));
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}
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}
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return declarations;
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}
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private boolean isAtViolationLocation(J.VariableDeclarations.NamedVariable literal) {
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final J.CompilationUnit cursor = getCursor().firstEnclosing(J.CompilationUnit.class);
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final int line = computeLinePosition(cursor, literal, getCursor());
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final int column = computeColumnPosition(cursor, literal, getCursor());
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return violations.stream().anyMatch(violation -> {
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return violation.getLine() == line
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&& violation.getColumn() == column
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&& Path.of(violation.getFileName()).equals(sourcePath);
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});
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}
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private int computePosition(
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J tree,
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J targetElement,
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Cursor cursor,
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Function<String, Integer> positionCalculator
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) {
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final TreeVisitor<?, PrintOutputCapture<TreeVisitor<?, ?>>> printer =
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tree.printer(cursor);
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final PrintOutputCapture<TreeVisitor<?, ?>> capture =
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new PrintOutputCapture<>(printer) {
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@Override
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public PrintOutputCapture<TreeVisitor<?, ?>> append(String text) {
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if (targetElement.isScope(getContext().getCursor().getValue())) {
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super.append(targetElement.getPrefix().getWhitespace());
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throw new CancellationException();
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}
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return super.append(text);
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}
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};
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final int result;
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try {
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printer.visit(tree, capture, cursor.getParentOrThrow());
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throw new IllegalStateException("Target element: " + targetElement
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+ ", not found in the syntax tree.");
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}
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catch (CancellationException exception) {
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result = positionCalculator.apply(capture.getOut());
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}
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catch (RecipeRunException exception) {
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if (exception.getCause() instanceof CancellationException) {
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result = positionCalculator.apply(capture.getOut());
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}
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else {
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throw exception;
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}
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}
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return result;
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}
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private int computeLinePosition(J tree, J targetElement, Cursor cursor) {
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return computePosition(tree, targetElement, cursor,
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out -> 1 + Math.toIntExact(out.chars().filter(chr -> chr == '\n').count()));
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}
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private int computeColumnPosition(J tree, J targetElement, Cursor cursor) {
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return computePosition(tree, targetElement, cursor, this::calculateColumnOffset);
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}
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private int calculateColumnOffset(String out) {
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final int lineBreakIndex = out.lastIndexOf('\n');
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final int result;
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if (lineBreakIndex == -1) {
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result = out.length();
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}
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else {
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result = out.length() - lineBreakIndex - 1;
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}
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return result;
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}
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}
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}

‎src/test/java/org/checkstyle/autofix/recipe/FinalLocalVariableTest.java

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///////////////////////////////////////////////////////////////////////////////////////////////
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// checkstyle-openrewrite-recipes: Automatically fix Checkstyle violations with OpenRewrite.
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// Copyright (C) 2025 The Checkstyle OpenRewrite Recipes Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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///////////////////////////////////////////////////////////////////////////////////////////////
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package org.checkstyle.autofix.recipe;
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import java.io.IOException;
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import java.nio.file.Path;
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import java.util.List;
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import org.checkstyle.autofix.parser.CheckstyleReportParser;
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import org.checkstyle.autofix.parser.CheckstyleViolation;
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import org.junit.jupiter.api.Test;
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import org.openrewrite.Recipe;
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public class FinalLocalVariableTest extends AbstractRecipeTest {
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@Override
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protected Recipe getRecipe() {
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final String reportPath = "src/test/resources/org/checkstyle/autofix/recipe"
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+ "/finallocalvariable/report.xml";
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final List<CheckstyleViolation> violations =
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CheckstyleReportParser.parse(Path.of(reportPath));
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return new FinalLocalVariable(violations);
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}
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@Test
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void hexOctalLiteralTest() throws IOException {
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testRecipe("finallocalvariable", "MissingFinal");
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}
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}

‎src/test/resources/org/checkstyle/autofix/recipe/finallocalvariable/missingfinal/InputMissingFinal.java

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package org.checkstyle.autofix.recipe.finallocalvariable.missingfinal;
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public class InputMissingFinal {
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public void computeSum() {
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int a = 5;
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int b = 10;
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int sum = a + b;
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System.out.println("Sum: " + sum);
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}
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}

‎src/test/resources/org/checkstyle/autofix/recipe/finallocalvariable/missingfinal/OutputMissingFinal.java

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package org.checkstyle.autofix.recipe.finallocalvariable.missingfinal;
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public class OutputMissingFinal {
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public void computeSum() {
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final int a = 5;
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final int b = 10;
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final int sum = a + b;
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System.out.println("Sum: " + sum);
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}
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}

‎src/test/resources/org/checkstyle/autofix/recipe/finallocalvariable/report.xml

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<?xml version="1.0" encoding="UTF-8"?>
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<checkstyle version="10.12.3">
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<file name="org/checkstyle/autofix/recipe/finallocalvariable/missingfinal/InputMissingFinal.java">
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<error line="5" column="12" severity="error"
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message="Variable should be declared final."
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source="com.puppycrawl.tools.checkstyle.checks.coding.FinalLocalVariableCheck"/>
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<error line="6" column="12" severity="error"
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message="Variable should be declared final."
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source="com.puppycrawl.tools.checkstyle.checks.coding.FinalLocalVariableCheck"/>
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<error line="7" column="12" severity="error"
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message="Variable should be declared final."
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source="com.puppycrawl.tools.checkstyle.checks.coding.FinalLocalVariableCheck"/>
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</file>
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</checkstyle>

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