Add step to forbid module imports

Author: Plunts

CHANGES.md

@@ -12,6 +12,8 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
 ## [Unreleased]
 ### Fixed
 - palantirJavaFormat is no longer arbitrarily set to outdated versions on Java 17, latest available version is always used ([#2686](https://github.com/diffplug/spotless/pull/2686) fixes [#2685](https://github.com/diffplug/spotless/issues/2685))
+### Added
+- Add a `forbidModuleImports` API for java ([#2679](https://github.com/diffplug/spotless/issues/2679))
 
 ## [4.0.0] - 2025-09-24
 ### Changes

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

@@ -0,0 +1,36 @@
+/*
+ * 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 com.diffplug.spotless.FormatterStep;
+import com.diffplug.spotless.generic.ReplaceRegexStep;
+
+/** Forbids any module import statements. */
+public final class ForbidModuleImportsStep {
+
+	/**
+	 * Matches lines like 'import module java.base;' or 'import module java.sql;'.
+	 */
+	private static final String REGEX = "(?m)^import module[^;\\n]*;\\R?";
+	private static final String NAME = "forbidModuleImports";
+	private static final String ERROR = "Do not use module imports - replace with specific class imports as 'spotlessApply' cannot auto-fix this";
+
+	private ForbidModuleImportsStep() {}
+
+	public static FormatterStep create() {
+		return ReplaceRegexStep.lint(NAME, REGEX, ERROR);
+	}
+}

plugin-gradle/CHANGES.md

@@ -5,6 +5,8 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
 ## [Unreleased]
 ### Fixed
 - palantirJavaFormat is no longer arbitrarily set to outdated versions on Java 17, latest available version is always used ([#2686](https://github.com/diffplug/spotless/pull/2686) fixes [#2685](https://github.com/diffplug/spotless/issues/2685))
+### Added
+- `forbidModuleImports()` API for java ([#2679](https://github.com/diffplug/spotless/issues/2679))
 
 ## [8.0.0] - 2025-09-24
 ### Changed

plugin-gradle/src/main/java/com/diffplug/gradle/spotless/JavaExtension.java

@@ -36,6 +36,7 @@
 import com.diffplug.spotless.extra.java.EclipseJdtFormatterStep;
 import com.diffplug.spotless.generic.LicenseHeaderStep;
 import com.diffplug.spotless.java.CleanthatJavaStep;
+import com.diffplug.spotless.java.ForbidModuleImportsStep;
 import com.diffplug.spotless.java.ForbidWildcardImportsStep;
 import com.diffplug.spotless.java.FormatAnnotationsStep;
 import com.diffplug.spotless.java.GoogleJavaFormatStep;
@@ -162,6 +163,10 @@ public void forbidWildcardImports() {
 		addStep(ForbidWildcardImportsStep.create());
 	}
 
+	public void forbidModuleImports() {
+		addStep(ForbidModuleImportsStep.create());
+	}
+
 	/** Uses the <a href="https://github.com/google/google-java-format">google-java-format</a> jar to format source code. */
 	public GoogleJavaFormatConfig googleJavaFormat() {
 		return googleJavaFormat(GoogleJavaFormatStep.defaultVersion());

plugin-gradle/src/test/java/com/diffplug/gradle/spotless/JavaDefaultTargetTest.java

@@ -101,6 +101,26 @@ void removeWildCardImports() throws IOException {
 		assertFile("test.java").sameAsResource("java/removewildcardimports/JavaCodeWildcardsFormatted.test");
 	}
 
+	@Test
+	void removeModuleImports() throws IOException {
+		setFile("build.gradle").toLines(
+				"plugins {",
+				"    id 'com.diffplug.spotless'",
+				"}",
+				"repositories { mavenCentral() }",
+				"",
+				"spotless {",
+				"    java {",
+				"        target file('test.java')",
+				"        forbidModuleImports()",
+				"    }",
+				"}");
+
+		setFile("test.java").toResource("java/forbidmoduleimports/JavaCodeModuleImportsUnformatted.test");
+		gradleRunner().withArguments("spotlessApply").buildAndFail();
+		assertFile("test.java").sameAsResource("java/forbidmoduleimports/JavaCodeModuleImportsFormatted.test");
+	}
+
 	/**
 	 * Triggers the special case in {@link FormatExtension#setupTask(SpotlessTask)} with {@code toggleFence} and
 	 * {@code targetExcludeContentPattern} both being not {@code null}.

plugin-maven/CHANGES.md

@@ -5,6 +5,8 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
 ## [Unreleased]
 ### Fixed
 - palantirJavaFormat is no longer arbitrarily set to outdated versions on Java 17, latest available version is always used ([#2686](https://github.com/diffplug/spotless/pull/2686) fixes [#2685](https://github.com/diffplug/spotless/issues/2685))
+### Added
+- `<forbidModuleImports>` API for java ([#2679](https://github.com/diffplug/spotless/issues/2679))
 
 ## [3.0.0] - 2025-09-24
 ### Changes

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

@@ -0,0 +1,28 @@
+/*
+ * 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 com.diffplug.spotless.FormatterStep;
+import com.diffplug.spotless.java.ForbidModuleImportsStep;
+import com.diffplug.spotless.maven.FormatterStepConfig;
+import com.diffplug.spotless.maven.FormatterStepFactory;
+
+public class ForbidModuleImports implements FormatterStepFactory {
+	@Override
+	public FormatterStep newFormatterStep(FormatterStepConfig config) {
+		return ForbidModuleImportsStep.create();
+	}
+}

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

@@ -80,6 +80,10 @@ public void addForbidWildcardImports(ForbidWildcardImports forbidWildcardImports
 		addStepFactory(forbidWildcardImports);
 	}
 
+	public void addForbidModuleImports(ForbidModuleImports forbidModuleImports) {
+		addStepFactory(forbidModuleImports);
+	}
+
 	public void addFormatAnnotations(FormatAnnotations formatAnnotations) {
 		addStepFactory(formatAnnotations);
 	}

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

@@ -0,0 +1,39 @@
+/*
+ * 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 ForbidModuleImportsStepTest extends MavenIntegrationHarness {
+
+	@Test
+	void testForbidModuleImports() throws Exception {
+		writePomWithJavaSteps("<forbidModuleImports/>");
+
+		String path = "src/main/java/test.java";
+		setFile(path).toResource("java/forbidmoduleimports/JavaCodeModuleImportsUnformatted.test");
+		var selfie = expectSelfieErrorMsg(mavenRunner().withArguments("spotless:apply").runHasError());
+		assertFile(path).sameAsResource("java/forbidmoduleimports/JavaCodeModuleImportsUnformatted.test");
+		selfie.toBe("""
+				Failed to execute goal com.diffplug.spotless:spotless-maven-plugin:VERSION:apply (default-cli) on project spotless-maven-plugin-tests: There were 2 lint error(s), they must be fixed or suppressed.
+				src/main/java/test.java:L1 forbidModuleImports(import module java.base;) Do not use module imports - replace with specific class imports as 'spotlessApply' cannot auto-fix this
+				src/main/java/test.java:L2 forbidModuleImports(import module java.sql;) Do not use module imports - replace with specific class imports as 'spotlessApply' cannot auto-fix this
+				Resolve these lints or suppress with `<lintSuppressions>`
+				""");
+	}
+}

testlib/src/main/resources/java/forbidmoduleimports/JavaCodeModuleImportsFormatted.test

@@ -0,0 +1,4 @@
+import module java.base;
+import module java.sql;
+
+public class Test {}