Add Maven plugin integration for ExpandWildcardImportsStep

plugin-maven/README.md

@@ -232,6 +232,7 @@ any other maven phase (i.e. compile) then it can be configured as below;
 
     <removeUnusedImports /> <!-- self-explanatory -->
     <forbidWildcardImports /> <!-- yell if any import ends with '*' -->
+    <expandWildcardImports /> <!-- replace wildcard imports with explicit imports -->
     <forbidModuleImports /> <!-- yell if any module imports are found (Java 25+) -->
 
     <formatAnnotations />  <!-- fixes formatting of type annotations, see below -->
@@ -257,6 +258,14 @@ any other maven phase (i.e. compile) then it can be configured as below;
 <forbidWildcardImports/>
 ```
 
+### expandWildcardImports
+
+Automatically replaces wildcard imports (e.g., `import java.util.*`) with explicit imports for the classes actually used in the code. This step analyzes your source code and project dependencies to determine which specific classes are needed and generates the appropriate import statements.
+
+```xml
+<expandWildcardImports/>
+```
+
 ### forbidModuleImports
 
 ```xml

plugin-maven/src/main/java/com/diffplug/spotless/maven/AbstractSpotlessMojo.java

@@ -397,7 +397,7 @@ private FormatterConfig getFormatterConfig() {
 		FileLocator fileLocator = getFileLocator();
 		final Optional<String> optionalRatchetFrom = Optional.ofNullable(this.ratchetFrom)
 				.filter(ratchet -> !RATCHETFROM_NONE.equals(ratchet));
-		return new FormatterConfig(baseDir, encoding, lineEndings, optionalRatchetFrom, provisioner, fileLocator, formatterStepFactories, Optional.ofNullable(setLicenseHeaderYearsFromGitHistory), lintSuppressions);
+		return new FormatterConfig(baseDir, encoding, lineEndings, optionalRatchetFrom, provisioner, fileLocator, formatterStepFactories, Optional.ofNullable(setLicenseHeaderYearsFromGitHistory), lintSuppressions, project);
 	}
 
 	private FileLocator getFileLocator() {

plugin-maven/src/main/java/com/diffplug/spotless/maven/FormatterConfig.java

@@ -21,6 +21,8 @@
 import java.util.List;
 import java.util.Optional;
 
+import org.apache.maven.project.MavenProject;
+
 import com.diffplug.spotless.LineEnding;
 import com.diffplug.spotless.LintSuppression;
 import com.diffplug.spotless.Provisioner;
@@ -35,9 +37,10 @@ public class FormatterConfig {
 	private final List<FormatterStepFactory> globalStepFactories;
 	private final Optional<String> spotlessSetLicenseHeaderYearsFromGitHistory;
 	private final List<LintSuppression> lintSuppressions;
+	private final MavenProject project;
 
 	public FormatterConfig(File baseDir, String encoding, LineEnding lineEndings, Optional<String> ratchetFrom, Provisioner provisioner,
-			FileLocator fileLocator, List<FormatterStepFactory> globalStepFactories, Optional<String> spotlessSetLicenseHeaderYearsFromGitHistory, List<LintSuppression> lintSuppressions) {
+			FileLocator fileLocator, List<FormatterStepFactory> globalStepFactories, Optional<String> spotlessSetLicenseHeaderYearsFromGitHistory, List<LintSuppression> lintSuppressions, MavenProject project) {
 		this.encoding = encoding;
 		this.lineEndings = lineEndings;
 		this.ratchetFrom = ratchetFrom;
@@ -46,6 +49,7 @@ public FormatterConfig(File baseDir, String encoding, LineEnding lineEndings, Op
 		this.globalStepFactories = globalStepFactories;
 		this.spotlessSetLicenseHeaderYearsFromGitHistory = spotlessSetLicenseHeaderYearsFromGitHistory;
 		this.lintSuppressions = lintSuppressions;
+		this.project = project;
 	}
 
 	public String getEncoding() {
@@ -79,4 +83,8 @@ public FileLocator getFileLocator() {
 	public List<LintSuppression> getLintSuppressions() {
 		return unmodifiableList(lintSuppressions);
 	}
+
+	public MavenProject getProject() {
+		return project;
+	}
 }

plugin-maven/src/main/java/com/diffplug/spotless/maven/FormatterFactory.java

@@ -185,7 +185,7 @@ Optional<String> ratchetFrom(FormatterConfig config) {
 	}
 
 	private FormatterStepConfig stepConfig(Charset encoding, FormatterConfig config) {
-		return new FormatterStepConfig(encoding, licenseHeaderDelimiter(), ratchetFrom(config), config.getProvisioner(), config.getFileLocator(), config.getSpotlessSetLicenseHeaderYearsFromGitHistory());
+		return new FormatterStepConfig(encoding, licenseHeaderDelimiter(), ratchetFrom(config), config.getProvisioner(), config.getFileLocator(), config.getSpotlessSetLicenseHeaderYearsFromGitHistory(), config.getProject());
 	}
 
 	private static List<FormatterStepFactory> gatherStepFactories(List<FormatterStepFactory> allGlobal, List<FormatterStepFactory> allConfigured) {

plugin-maven/src/main/java/com/diffplug/spotless/maven/FormatterStepConfig.java

@@ -18,6 +18,8 @@
 import java.nio.charset.Charset;
 import java.util.Optional;
 
+import org.apache.maven.project.MavenProject;
+
 import com.diffplug.spotless.Provisioner;
 
 public class FormatterStepConfig {
@@ -28,14 +30,16 @@ public class FormatterStepConfig {
 	private final Provisioner provisioner;
 	private final FileLocator fileLocator;
 	private final Optional<String> spotlessSetLicenseHeaderYearsFromGitHistory;
+	private final MavenProject project;
 
-	public FormatterStepConfig(Charset encoding, String licenseHeaderDelimiter, Optional<String> ratchetFrom, Provisioner provisioner, FileLocator fileLocator, Optional<String> spotlessSetLicenseHeaderYearsFromGitHistory) {
+	public FormatterStepConfig(Charset encoding, String licenseHeaderDelimiter, Optional<String> ratchetFrom, Provisioner provisioner, FileLocator fileLocator, Optional<String> spotlessSetLicenseHeaderYearsFromGitHistory, MavenProject project) {
 		this.encoding = encoding;
 		this.licenseHeaderDelimiter = licenseHeaderDelimiter;
 		this.ratchetFrom = ratchetFrom;
 		this.provisioner = provisioner;
 		this.fileLocator = fileLocator;
 		this.spotlessSetLicenseHeaderYearsFromGitHistory = spotlessSetLicenseHeaderYearsFromGitHistory;
+		this.project = project;
 	}
 
 	public Charset getEncoding() {
@@ -61,4 +65,8 @@ public FileLocator getFileLocator() {
 	public Optional<String> spotlessSetLicenseHeaderYearsFromGitHistory() {
 		return spotlessSetLicenseHeaderYearsFromGitHistory;
 	}
+
+	public MavenProject getProject() {
+		return project;
+	}
 }

plugin-maven/src/main/java/com/diffplug/spotless/maven/java/ExpandWildcardImports.java

@@ -0,0 +1,58 @@
+/*
+ * 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.maven.java;
+
+import java.io.File;
+import java.util.HashSet;
+import java.util.Objects;
+import java.util.Set;
+
+import org.apache.maven.artifact.Artifact;
+import org.apache.maven.project.MavenProject;
+
+import com.diffplug.spotless.FormatterStep;
+import com.diffplug.spotless.java.ExpandWildcardImportsStep;
+import com.diffplug.spotless.maven.FormatterStepConfig;
+import com.diffplug.spotless.maven.FormatterStepFactory;
+
+public class ExpandWildcardImports implements FormatterStepFactory {
+
+	@Override
+	public FormatterStep newFormatterStep(FormatterStepConfig config) {
+		MavenProject project = config.getProject();
+		Set<File> typeSolverClasspath = new HashSet<>();
+
+		// Add all main source roots
+		project.getCompileSourceRoots().stream()
+				.map(File::new)
+				.filter(File::exists)
+				.forEach(typeSolverClasspath::add);
+
+		// Add all test source roots
+		project.getTestCompileSourceRoots().stream()
+				.map(File::new)
+				.filter(File::exists)
+				.forEach(typeSolverClasspath::add);
+
+		// Add compiled dependencies
+		project.getArtifacts().stream()
+				.map(Artifact::getFile)
+				.filter(Objects::nonNull)
+				.forEach(typeSolverClasspath::add);
+
+		return ExpandWildcardImportsStep.create(typeSolverClasspath, config.getProvisioner());
+	}
+}

plugin-maven/src/main/java/com/diffplug/spotless/maven/java/Java.java

@@ -88,6 +88,10 @@ public void addFormatAnnotations(FormatAnnotations formatAnnotations) {
 		addStepFactory(formatAnnotations);
 	}
 
+	public void addExpandWildcardImports(ExpandWildcardImports expandWildcardImports) {
+		addStepFactory(expandWildcardImports);
+	}
+
 	public void addCleanthat(CleanthatJava cleanthat) {
 		addStepFactory(cleanthat);
 	}

plugin-maven/src/test/java/com/diffplug/spotless/maven/java/ExpandWildcardImportsStepTest.java

@@ -0,0 +1,48 @@
+/*
+ * 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.maven.java;
+
+import org.junit.jupiter.api.Test;
+
+import com.diffplug.spotless.maven.MavenIntegrationHarness;
+
+class ExpandWildcardImportsStepTest extends MavenIntegrationHarness {
+
+	@Test
+	void testExpandWildcardImports() throws Exception {
+		writePomWithJavaSteps("<expandWildcardImports/>");
+
+		// Create the supporting classes needed for import resolution
+		setFile("src/main/java/foo/bar/AnotherClassInSamePackage.java")
+				.toResource("java/expandwildcardimports/AnotherClassInSamePackage.test");
+		setFile("src/main/java/foo/bar/baz/AnotherImportedClass.java")
+				.toResource("java/expandwildcardimports/AnotherImportedClass.test");
+
+		// Create the annotation class that's used in the test
+		setFile("src/main/java/org/example/SomeAnnotation.java")
+				.toContent("package org.example;\n\npublic @interface SomeAnnotation {}\n");
+
+		// Set the main file to format
+		String path = "src/main/java/foo/bar/JavaClassWithWildcards.java";
+		setFile(path).toResource("java/expandwildcardimports/JavaClassWithWildcardsUnformatted.test");
+
+		// Run spotless:apply
+		mavenRunner().withArguments("spotless:apply").runNoError();
+
+		// Verify the wildcards were expanded
+		assertFile(path).sameAsResource("java/expandwildcardimports/JavaClassWithWildcardsFormatted.test");
+	}
+}