Add support for prince-of-space Java formatter

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 support for Java formatting via [`prince-of-space`](https://github.com/agustafson/prince-of-space). ([#2991](https://github.com/diffplug/spotless/pull/2991))
 
 ## [4.8.0] - 2026-06-29
 ### Added

gradle/libs.versions.toml

@@ -53,6 +53,7 @@ gson = "com.google.code.gson:gson:2.14.0"
 javaparser-symbol-solver-core = "com.github.javaparser:javaparser-symbol-solver-core:3.27.1"
 ktfmt = "com.facebook:ktfmt:0.63"
 palantir-java-format = "com.palantir.javaformat:palantir-java-format:1.1.0"
+prince-of-space-core = "io.github.agustafson.princeofspace:prince-of-space-core:2.2.0"
 scalafmt-core = "org.scalameta:scalafmt-core_2.13:3.8.1"
 sortpom-sorter = "com.github.ekryd.sortpom:sortpom-sorter:4.0.0"
 tabletest-formatter-core = "org.tabletest:tabletest-formatter-core:1.1.1"

lib/build.gradle

@@ -22,6 +22,7 @@ def NEEDS_GLUE = [
 	'ktfmt',
 	'ktlint',
 	'palantirJavaFormat',
+	'princeOfSpace',
 	'scalafmt',
 	'sortPom',
 	'tableTestFormatter',
@@ -117,6 +118,8 @@ dependencies {
 	compatKtLint1Dot0Dot0CompileAndTestOnly libs.slf4j.api
 	// palantirJavaFormat
 	palantirJavaFormatCompileOnly libs.palantir.java.format 	// this version needs to stay compilable against Java 8 for CI Job testNpm
+	// princeOfSpace
+	princeOfSpaceCompileOnly libs.prince.of.space.core
 	// scalafmt
 	scalafmtCompileOnly libs.scalafmt.core
 	// sortPom

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

@@ -0,0 +1,159 @@
+/*
+ * Copyright 2026 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.Serial;
+import java.io.Serializable;
+import java.lang.reflect.Constructor;
+import java.util.Objects;
+
+import javax.annotation.Nullable;
+
+import com.diffplug.spotless.FormatterFunc;
+import com.diffplug.spotless.FormatterStep;
+import com.diffplug.spotless.JarState;
+import com.diffplug.spotless.Jvm;
+import com.diffplug.spotless.Provisioner;
+
+/** Wraps up <a href="https://github.com/agustafson/prince-of-space">prince-of-space</a> as a FormatterStep. */
+public final class PrinceOfSpaceStep implements Serializable {
+	@Serial
+	private static final long serialVersionUID = 1L;
+	private static final String NAME = "prince-of-space";
+	public static final String MAVEN_COORDINATE = "io.github.agustafson.princeofspace:prince-of-space-core:";
+	public static final String DEFAULT_VERSION = "2.2.0";
+
+	/** The jar that contains the formatter. */
+	private final JarState.Promised jarState;
+	/** Version of the formatter jar. */
+	private final String formatterVersion;
+	@Nullable private final Options options;
+
+	private PrinceOfSpaceStep(JarState.Promised jarState, String formatterVersion, @Nullable Options options) {
+		this.jarState = jarState;
+		this.formatterVersion = formatterVersion;
+		this.options = options;
+	}
+
+	/** Creates a step which formats Java source with prince-of-space's default options. */
+	public static FormatterStep create(Provisioner provisioner) {
+		return create(defaultVersion(), provisioner);
+	}
+
+	/** Creates a step which formats Java source with prince-of-space's default options. */
+	public static FormatterStep create(String version, Provisioner provisioner) {
+		return create(version, provisioner, null);
+	}
+
+	/** Creates a step which formats Java source with the given options. */
+	public static FormatterStep create(String version, Provisioner provisioner, @Nullable Options options) {
+		Objects.requireNonNull(version, "version");
+		Objects.requireNonNull(provisioner, "provisioner");
+		return FormatterStep.create(NAME,
+				new PrinceOfSpaceStep(JarState.promise(() -> JarState.from(MAVEN_COORDINATE + version, provisioner)), version, options),
+				PrinceOfSpaceStep::equalityState,
+				State::createFormat);
+	}
+
+	/** Get default formatter version */
+	public static String defaultVersion() {
+		return DEFAULT_VERSION;
+	}
+
+	private State equalityState() {
+		return new State(jarState.get(), formatterVersion, options);
+	}
+
+	/** Mutable bag of the optional prince-of-space {@code FormatterConfig} knobs; unset (null) fields keep prince-of-space's own defaults. */
+	public static class Options implements Serializable {
+		@Serial
+		private static final long serialVersionUID = 1L;
+
+		@Nullable private String indentStyle;
+		@Nullable private Integer indentSize;
+		@Nullable private Integer lineLength;
+		@Nullable private String wrapStyle;
+		@Nullable private Boolean closingParenOnNewLine;
+		@Nullable private Boolean trailingCommas;
+		@Nullable private Integer javaLanguageLevel;
+
+		public Options() {}
+
+		public void setIndentStyle(String indentStyle) {
+			this.indentStyle = indentStyle;
+		}
+
+		public void setIndentSize(int indentSize) {
+			this.indentSize = indentSize;
+		}
+
+		public void setLineLength(int lineLength) {
+			this.lineLength = lineLength;
+		}
+
+		public void setWrapStyle(String wrapStyle) {
+			this.wrapStyle = wrapStyle;
+		}
+
+		public void setClosingParenOnNewLine(boolean closingParenOnNewLine) {
+			this.closingParenOnNewLine = closingParenOnNewLine;
+		}
+
+		public void setTrailingCommas(boolean trailingCommas) {
+			this.trailingCommas = trailingCommas;
+		}
+
+		public void setJavaLanguageLevel(int javaLanguageLevel) {
+			this.javaLanguageLevel = javaLanguageLevel;
+		}
+	}
+
+	private static final class State implements Serializable {
+		@Serial
+		private static final long serialVersionUID = 1L;
+
+		private final JarState jarState;
+		private final String formatterVersion;
+		@Nullable private final Options options;
+
+		State(JarState jarState, String formatterVersion, @Nullable Options options) {
+			if (Jvm.version() < 17) {
+				throw new IllegalStateException("prince-of-space requires a JDK 17+ host runtime, this JVM is " + Jvm.version());
+			}
+			this.jarState = jarState;
+			this.formatterVersion = formatterVersion;
+			this.options = options;
+		}
+
+		FormatterFunc createFormat() throws Exception {
+			final ClassLoader classLoader = jarState.getClassLoader();
+			final Class<?> formatterFunc = classLoader.loadClass("com.diffplug.spotless.glue.pos.PrinceOfSpaceFormatterFunc");
+			final Constructor<?> constructor = formatterFunc.getConstructor(
+					String.class, Integer.class, Integer.class, String.class, Boolean.class, Boolean.class, Integer.class);
+			if (options == null) {
+				return (FormatterFunc) constructor.newInstance(null, null, null, null, null, null, null);
+			}
+			return (FormatterFunc) constructor.newInstance(
+					options.indentStyle,
+					options.indentSize,
+					options.lineLength,
+					options.wrapStyle,
+					options.closingParenOnNewLine,
+					options.trailingCommas,
+					options.javaLanguageLevel);
+		}
+	}
+}

lib/src/princeOfSpace/java/com/diffplug/spotless/glue/pos/PrinceOfSpaceFormatterFunc.java

@@ -0,0 +1,68 @@
+/*
+ * Copyright 2026 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.pos;
+
+import java.io.File;
+
+import io.princeofspace.Formatter;
+import io.princeofspace.model.FormatterConfig;
+import io.princeofspace.model.IndentStyle;
+import io.princeofspace.model.JavaLanguageLevel;
+import io.princeofspace.model.WrapStyle;
+
+import com.diffplug.spotless.FormatterFunc;
+
+public class PrinceOfSpaceFormatterFunc implements FormatterFunc.NeedsFile {
+
+	private final Formatter formatter;
+
+	public PrinceOfSpaceFormatterFunc(String indentStyle, Integer indentSize, Integer lineLength, String wrapStyle,
+			Boolean closingParenOnNewLine, Boolean trailingCommas, Integer javaLanguageLevel) {
+		FormatterConfig.Builder builder = FormatterConfig.builder();
+		if (indentStyle != null) {
+			builder.indentStyle(IndentStyle.valueOf(indentStyle));
+		}
+		if (indentSize != null) {
+			builder.indentSize(indentSize);
+		}
+		if (lineLength != null) {
+			builder.lineLength(lineLength);
+		}
+		if (wrapStyle != null) {
+			builder.wrapStyle(WrapStyle.valueOf(wrapStyle));
+		}
+		if (closingParenOnNewLine != null) {
+			builder.closingParenOnNewLine(closingParenOnNewLine);
+		}
+		if (trailingCommas != null) {
+			builder.trailingCommas(trailingCommas);
+		}
+		if (javaLanguageLevel != null) {
+			builder.javaLanguageLevel(JavaLanguageLevel.of(javaLanguageLevel));
+		}
+		this.formatter = new Formatter(builder.build());
+	}
+
+	@Override
+	public String applyWithFile(String unix, File file) throws Exception {
+		return formatter.format(unix, file.toPath());
+	}
+
+	@Override
+	public String toString() {
+		return "PrinceOfSpaceFormatterFunc{formatter=" + formatter + '}';
+	}
+}

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 support for Java formatting via [`prince-of-space`](https://github.com/agustafson/prince-of-space) with the new `princeOfSpace()` step. ([#2991](https://github.com/diffplug/spotless/pull/2991))
 
 ## [8.8.0] - 2026-06-29
 ### Added

plugin-gradle/README.md

@@ -56,7 +56,7 @@ Spotless supports all of Gradle's built-in performance features (incremental bui
   - [Git hook (optional)](#git-hook)
   - [Linting](#linting)
 - **Languages**
-  - [Java](#java) ([google-java-format](#google-java-format), [eclipse jdt](#eclipse-jdt), [clang-format](#clang-format), [prettier](#prettier), [palantir-java-format](#palantir-java-format), [formatAnnotations](#formatAnnotations), [cleanthat](#cleanthat), [tabletest-formatter](#tabletest-formatter), [IntelliJ IDEA](#intellij-idea))
+  - [Java](#java) ([google-java-format](#google-java-format), [eclipse jdt](#eclipse-jdt), [clang-format](#clang-format), [prettier](#prettier), [palantir-java-format](#palantir-java-format), [prince-of-space](#prince-of-space), [formatAnnotations](#formatAnnotations), [cleanthat](#cleanthat), [tabletest-formatter](#tabletest-formatter), [IntelliJ IDEA](#intellij-idea))
   - [Groovy](#groovy) ([eclipse groovy](#eclipse-groovy))
   - [Kotlin](#kotlin) ([ktfmt](#ktfmt), [ktlint](#ktlint), [diktat](#diktat), [tabletest-formatter](#tabletest-formatter-1), [prettier](#prettier))
   - [Scala](#scala) ([scalafmt](#scalafmt))
@@ -312,6 +312,24 @@ spotless {
     palantirJavaFormat('2.39.0').formatJavadoc(true)
 ```
 
+### prince-of-space
+
+[homepage](https://github.com/agustafson/prince-of-space). Requires a JDK 17+ host runtime.
+```gradle
+spotless {
+  java {
+    princeOfSpace()
+    // optional: configure any of the formatter's options
+    princeOfSpace('2.2.0')
+        .indentStyle('SPACES') // or 'TABS'
+        .indentSize(4)
+        .lineLength(120)
+        .wrapStyle('BALANCED') // or 'WIDE', 'NARROW'
+        .closingParenOnNewLine(true)
+        .trailingCommas(false)
+        .javaLanguageLevel(17)
+```
+
 ### eclipse jdt
 
 [homepage](https://download.eclipse.org/eclipse/downloads/). See [here](../ECLIPSE_SCREENSHOTS.md) for screenshots that demonstrate how to get and install the config file mentioned below.

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

@@ -46,6 +46,7 @@
 import com.diffplug.spotless.java.GoogleJavaFormatStep;
 import com.diffplug.spotless.java.ImportOrderStep;
 import com.diffplug.spotless.java.PalantirJavaFormatStep;
+import com.diffplug.spotless.java.PrinceOfSpaceStep;
 import com.diffplug.spotless.java.RemoveUnusedImportsStep;
 import com.diffplug.spotless.java.TableTestFormatterStep;
 
@@ -308,6 +309,73 @@ private FormatterStep createStep() {
 		}
 	}
 
+	/** Uses the <a href="https://github.com/agustafson/prince-of-space">prince-of-space</a> jar to format source code. */
+	public PrinceOfSpaceConfig princeOfSpace() {
+		return princeOfSpace(PrinceOfSpaceStep.defaultVersion());
+	}
+
+	/** Uses the given version of <a href="https://github.com/agustafson/prince-of-space">prince-of-space</a> to format source code. */
+	public PrinceOfSpaceConfig princeOfSpace(String version) {
+		Objects.requireNonNull(version);
+		return new PrinceOfSpaceConfig(version);
+	}
+
+	public class PrinceOfSpaceConfig {
+		final String version;
+		final PrinceOfSpaceStep.Options options = new PrinceOfSpaceStep.Options();
+
+		PrinceOfSpaceConfig(String version) {
+			this.version = Objects.requireNonNull(version);
+			addStep(createStep());
+		}
+
+		public PrinceOfSpaceConfig indentStyle(String indentStyle) {
+			options.setIndentStyle(indentStyle);
+			replaceStep(createStep());
+			return this;
+		}
+
+		public PrinceOfSpaceConfig indentSize(int indentSize) {
+			options.setIndentSize(indentSize);
+			replaceStep(createStep());
+			return this;
+		}
+
+		public PrinceOfSpaceConfig lineLength(int lineLength) {
+			options.setLineLength(lineLength);
+			replaceStep(createStep());
+			return this;
+		}
+
+		public PrinceOfSpaceConfig wrapStyle(String wrapStyle) {
+			options.setWrapStyle(wrapStyle);
+			replaceStep(createStep());
+			return this;
+		}
+
+		public PrinceOfSpaceConfig closingParenOnNewLine(boolean closingParenOnNewLine) {
+			options.setClosingParenOnNewLine(closingParenOnNewLine);
+			replaceStep(createStep());
+			return this;
+		}
+
+		public PrinceOfSpaceConfig trailingCommas(boolean trailingCommas) {
+			options.setTrailingCommas(trailingCommas);
+			replaceStep(createStep());
+			return this;
+		}
+
+		public PrinceOfSpaceConfig javaLanguageLevel(int javaLanguageLevel) {
+			options.setJavaLanguageLevel(javaLanguageLevel);
+			replaceStep(createStep());
+			return this;
+		}
+
+		private FormatterStep createStep() {
+			return PrinceOfSpaceStep.create(version, provisioner(), options);
+		}
+	}
+
 	public EclipseConfig eclipse() {
 		return eclipse(EclipseJdtFormatterStep.defaultVersion());
 	}

plugin-maven/CHANGES.md

@@ -3,6 +3,8 @@
 We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (starting after version `1.27.0`).
 
 ## [Unreleased]
+### Added
+- Add support for Java formatting via [`prince-of-space`](https://github.com/agustafson/prince-of-space) with the new `<princeOfSpace>` step. ([#2991](https://github.com/diffplug/spotless/pull/2991))
 
 ## [3.8.0] - 2026-06-29
 ### Added