new step to expand java wildcard imports

CHANGES.md

@@ -10,6 +10,8 @@ This document is intended for Spotless developers.
 We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (starting after version `1.27.0`).
 
 ## [Unreleased]
+### Added
+- Add a `expandWildcardImports` API for java ([#2679](https://github.com/diffplug/spotless/issues/2594))
 
 ## [4.1.0] - 2025-11-18
 ### Changes

build.gradle

@@ -10,7 +10,6 @@ apply from: rootProject.file('gradle/java-publish.gradle')
 apply from: rootProject.file('gradle/changelog.gradle')
 apply from: rootProject.file('gradle/rewrite.gradle')
 allprojects {
-	apply from: rootProject.file('gradle/error-prone.gradle')
 	apply from: rootProject.file('gradle/spotless.gradle')
 }
 apply from: rootProject.file('gradle/spotless-freshmark.gradle')

lib/build.gradle

@@ -18,6 +18,7 @@ def NEEDS_GLUE = [
 	'googleJavaFormat',
 	'gson',
 	'jackson',
+	'javaParser',
 	'ktfmt',
 	'ktlint',
 	'palantirJavaFormat',
@@ -100,6 +101,8 @@ dependencies {
 	String VER_JACKSON='2.20.1'
 	jacksonCompileOnly "com.fasterxml.jackson.core:jackson-databind:$VER_JACKSON"
 	jacksonCompileOnly "com.fasterxml.jackson.dataformat:jackson-dataformat-yaml:$VER_JACKSON"
+	// javaParser
+	javaParserCompileOnly "com.github.javaparser:javaparser-symbol-solver-core:3.27.1"
 	// ktfmt
 	ktfmtCompileOnly "com.facebook:ktfmt:0.59"
 	ktfmtCompileOnly("com.google.googlejavaformat:google-java-format") {

lib/src/javaParser/java/com/diffplug/spotless/glue/javaParser/ExpandWildcardsFormatterFunc.java

@@ -0,0 +1,203 @@
+/*
+ * Copyright 2023-2025 DiffPlug
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.diffplug.spotless.glue.javaparser;
+
+import static java.util.stream.Collectors.joining;
+import static java.util.stream.Collectors.toMap;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Comparator;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.TreeSet;
+import java.util.function.Function;
+import java.util.regex.Pattern;
+import javassist.ClassPool;
+
+import com.github.javaparser.JavaParser;
+import com.github.javaparser.ast.CompilationUnit;
+import com.github.javaparser.ast.ImportDeclaration;
+import com.github.javaparser.ast.Node;
+import com.github.javaparser.ast.expr.AnnotationExpr;
+import com.github.javaparser.ast.expr.MarkerAnnotationExpr;
+import com.github.javaparser.ast.expr.MethodCallExpr;
+import com.github.javaparser.ast.expr.NormalAnnotationExpr;
+import com.github.javaparser.ast.expr.SingleMemberAnnotationExpr;
+import com.github.javaparser.ast.type.ClassOrInterfaceType;
+import com.github.javaparser.ast.visitor.VoidVisitorAdapter;
+import com.github.javaparser.resolution.SymbolResolver;
+import com.github.javaparser.resolution.UnsolvedSymbolException;
+import com.github.javaparser.resolution.declarations.ResolvedAnnotationDeclaration;
+import com.github.javaparser.resolution.declarations.ResolvedMethodDeclaration;
+import com.github.javaparser.resolution.types.ResolvedType;
+import com.github.javaparser.symbolsolver.JavaSymbolSolver;
+import com.github.javaparser.symbolsolver.resolution.typesolvers.CombinedTypeSolver;
+import com.github.javaparser.symbolsolver.resolution.typesolvers.JarTypeSolver;
+import com.github.javaparser.symbolsolver.resolution.typesolvers.JavaParserTypeSolver;
+import com.github.javaparser.symbolsolver.resolution.typesolvers.ReflectionTypeSolver;
+
+import com.diffplug.spotless.FormatterFunc;
+import com.diffplug.spotless.LineEnding;
+import com.diffplug.spotless.Lint;
+
+public class ExpandWildcardsFormatterFunc implements FormatterFunc.NeedsFile {
+
+	private final JavaParser parser;
+	static {
+		// If ClassPool is allowed to cache class files, it does not free the file-lock
+		ClassPool.cacheOpenedJarFile = false;
+	}
+
+	public ExpandWildcardsFormatterFunc(Collection<File> typeSolverClasspath) throws IOException {
+		this.parser = new JavaParser();
+
+		CombinedTypeSolver combinedTypeSolver = new CombinedTypeSolver();
+		combinedTypeSolver.add(new ReflectionTypeSolver());
+		for (File element : typeSolverClasspath) {
+			if (element.isFile()) {
+				combinedTypeSolver.add(new JarTypeSolver(element));
+			} else if (element.isDirectory()) {
+				combinedTypeSolver.add(new JavaParserTypeSolver(element));
+			} // gracefully ignore non-existing src-directories
+		}
+
+		SymbolResolver symbolSolver = new JavaSymbolSolver(combinedTypeSolver);
+		parser.getParserConfiguration().setSymbolResolver(symbolSolver);
+	}
+
+	@Override
+	public String applyWithFile(String rawUnix, File file) throws Exception {
+		Optional<CompilationUnit> parseResult = parser.parse(rawUnix).getResult();
+		if (parseResult.isEmpty()) {
+			return rawUnix;
+		}
+		CompilationUnit cu = parseResult.get();
+		Map<ImportDeclaration, Set<ImportDeclaration>> importMap = findWildcardImports(cu)
+				.stream()
+				.collect(toMap(Function.identity(),
+						t -> new TreeSet<>(Comparator.comparing(ImportDeclaration::getNameAsString))));
+		if (importMap.isEmpty()) {
+			// No wildcards found => do not change anything
+			return rawUnix;
+		}
+
+		cu.accept(new CollectImportedTypesVisitor(), importMap);
+		for (var entry : importMap.entrySet()) {
+			String pattern = Pattern.quote(LineEnding.toUnix(entry.getKey().toString()));
+			String replacement = entry.getValue().stream().map(ImportDeclaration::toString).collect(joining());
+			rawUnix = rawUnix.replaceAll(pattern, replacement);
+		}
+
+		return rawUnix;
+	}
+
+	private List<ImportDeclaration> findWildcardImports(CompilationUnit cu) {
+		List<ImportDeclaration> wildcardImports = new ArrayList<>();
+		for (ImportDeclaration importDeclaration : cu.getImports()) {
+			if (importDeclaration.isAsterisk()) {
+				wildcardImports.add(importDeclaration);
+			}
+		}
+		return wildcardImports;
+	}
+
+	private static final class CollectImportedTypesVisitor
+			extends VoidVisitorAdapter<Map<ImportDeclaration, Set<ImportDeclaration>>> {
+
+		@Override
+		public void visit(final ClassOrInterfaceType n,
+				final Map<ImportDeclaration, Set<ImportDeclaration>> importMap) {
+			// default imports
+			ResolvedType resolvedType = wrapUnsolvedSymbolException(n, ClassOrInterfaceType::resolve);
+			if (resolvedType.isReference()) {
+				matchTypeName(importMap, resolvedType.asReferenceType().getQualifiedName(), false);
+			}
+			super.visit(n, importMap);
+		}
+
+		private void matchTypeName(Map<ImportDeclaration, Set<ImportDeclaration>> importMap, String qualifiedName,
+				boolean isStatic) {
+			for (var entry : importMap.entrySet()) {
+				if (entry.getKey().isStatic() == isStatic
+						&& qualifiedName.startsWith(entry.getKey().getName().asString())) {
+					entry.getValue().add(new ImportDeclaration(qualifiedName, isStatic, false));
+					break;
+				}
+			}
+		}
+
+		@Override
+		public void visit(final MarkerAnnotationExpr n,
+				final Map<ImportDeclaration, Set<ImportDeclaration>> importMap) {
+			visitAnnotation(n, importMap);
+			super.visit(n, importMap);
+		}
+
+		@Override
+		public void visit(final SingleMemberAnnotationExpr n,
+				final Map<ImportDeclaration, Set<ImportDeclaration>> importMap) {
+			visitAnnotation(n, importMap);
+			super.visit(n, importMap);
+		}
+
+		@Override
+		public void visit(final NormalAnnotationExpr n,
+				final Map<ImportDeclaration, Set<ImportDeclaration>> importMap) {
+			visitAnnotation(n, importMap);
+			super.visit(n, importMap);
+		}
+
+		private void visitAnnotation(final AnnotationExpr n,
+				final Map<ImportDeclaration, Set<ImportDeclaration>> importMap) {
+			ResolvedAnnotationDeclaration resolvedType = wrapUnsolvedSymbolException(n, AnnotationExpr::resolve);
+			matchTypeName(importMap, resolvedType.getQualifiedName(), false);
+		}
+
+		@Override
+		public void visit(final MethodCallExpr n, final Map<ImportDeclaration, Set<ImportDeclaration>> importMap) {
+			// static imports
+			ResolvedMethodDeclaration resolved = wrapUnsolvedSymbolException(n, MethodCallExpr::resolve);
+			if (resolved.isStatic()) {
+				matchTypeName(importMap, resolved.getQualifiedName(), true);
+			}
+			super.visit(n, importMap);
+		}
+
+		private static <T extends Node, R> R wrapUnsolvedSymbolException(T node, Function<T, R> func) {
+			try {
+				return func.apply(node);
+			} catch (UnsolvedSymbolException ex) {
+				if (node.getBegin().isPresent() && node.getEnd().isPresent()) {
+					throw Lint.atLineRange(node.getBegin().get().line, node.getEnd().get().line, "UnsolvedSymbolException", ex.getMessage()).shortcut();
+				}
+				if (node.getBegin().isPresent()) {
+					throw Lint.atLine(node.getBegin().get().line, "UnsolvedSymbolException", ex.getMessage()).shortcut();
+				} else if (node.getEnd().isPresent()) {
+					throw Lint.atLine(node.getEnd().get().line, "UnsolvedSymbolException", ex.getMessage()).shortcut();
+				} else {
+					throw Lint.atUndefinedLine("UnsolvedSymbolException", ex.getMessage()).shortcut();
+				}
+			}
+		}
+
+	}
+
+}

lib/src/main/java/com/diffplug/spotless/java/ExpandWildcardImportsStep.java

@@ -0,0 +1,87 @@
+/*
+ * Copyright 2025 DiffPlug
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.diffplug.spotless.java;
+
+import java.io.File;
+import java.io.Serial;
+import java.io.Serializable;
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+import java.util.Collection;
+import java.util.Objects;
+import java.util.Set;
+
+import com.diffplug.spotless.FormatterFunc;
+import com.diffplug.spotless.FormatterStep;
+import com.diffplug.spotless.JarState;
+import com.diffplug.spotless.Provisioner;
+
+public final class ExpandWildcardImportsStep implements Serializable {
+	@Serial
+	private static final long serialVersionUID = 1L;
+
+	private static final String INCOMPATIBLE_ERROR_MESSAGE = "There was a problem interacting with Java-Parser; maybe you set an incompatible version?";
+	private static final String MAVEN_COORDINATES = "com.github.javaparser:javaparser-symbol-solver-core";
+	public static final String DEFAULT_VERSION = "3.27.1";
+
+	private final Collection<File> typeSolverClasspath;
+	private final JarState.Promised jarState;
+
+	private ExpandWildcardImportsStep(Collection<File> typeSolverClasspath, JarState.Promised jarState) {
+		this.typeSolverClasspath = typeSolverClasspath;
+		this.jarState = jarState;
+	}
+
+	public static FormatterStep create(Set<File> typeSolverClasspath, Provisioner provisioner) {
+		Objects.requireNonNull(provisioner, "provisioner cannot be null");
+		return FormatterStep.create("expandwildcardimports",
+				new ExpandWildcardImportsStep(typeSolverClasspath,
+						JarState.promise(() -> JarState.from(MAVEN_COORDINATES + ":" + DEFAULT_VERSION, provisioner))),
+				ExpandWildcardImportsStep::equalityState,
+				State::toFormatter);
+	}
+
+	private State equalityState() {
+		return new State(typeSolverClasspath, jarState.get());
+	}
+
+	private static class State implements Serializable {
+		@Serial
+		private static final long serialVersionUID = 1L;
+
+		private final Collection<File> typeSolverClasspath;
+		private final JarState jarState;
+
+		public State(Collection<File> typeSolverClasspath, JarState jarState) {
+			this.typeSolverClasspath = typeSolverClasspath;
+			this.jarState = jarState;
+		}
+
+		FormatterFunc toFormatter() {
+			try {
+				Class<?> formatterFunc = jarState.getClassLoader()
+						.loadClass("com.diffplug.spotless.glue.javaParser.ExpandWildcardsFormatterFunc");
+				Constructor<?> constructor = formatterFunc.getConstructor(Collection.class);
+				return (FormatterFunc) constructor.newInstance(typeSolverClasspath);
+			} catch (ClassNotFoundException | NoSuchMethodException | InvocationTargetException
+					| InstantiationException | IllegalAccessException | NoClassDefFoundError cause) {
+				throw new IllegalStateException(INCOMPATIBLE_ERROR_MESSAGE, cause);
+			}
+		}
+
+	}
+
+}

plugin-gradle/CHANGES.md

@@ -3,6 +3,8 @@
 We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (starting after version `3.27.0`).
 
 ## [Unreleased]
+### Added
+- Add a `expandWildcardImports` API for java ([#2679](https://github.com/diffplug/spotless/issues/2594))
 
 ## [8.1.0] - 2025-11-18
 ### Changes