Fixes #776: Add settings for the kind of newline to use

gson/src/main/java/com/google/gson/Gson.java

@@ -69,7 +69,7 @@
  *
  * <p>You can create a Gson instance by invoking {@code new Gson()} if the default configuration
  * is all you need. You can also use {@link GsonBuilder} to build a Gson instance with various
- * configuration options such as versioning support, pretty printing, custom
+ * configuration options such as versioning support, pretty printing, custom newline, custom
  * {@link JsonSerializer}s, {@link JsonDeserializer}s, and {@link InstanceCreator}s.</p>
  *
  * <p>Here is an example of how Gson is used for a simple Class:
@@ -142,6 +142,7 @@ public final class Gson {
  static final boolean DEFAULT_JSON_NON_EXECUTABLE = false;
  static final boolean DEFAULT_LENIENT = false;
  static final boolean DEFAULT_PRETTY_PRINT = false;
+ static final NewlineStyle DEFAULT_NEWLINE_STYLE = NewlineStyle.MACOS_AND_LINUX;
  static final boolean DEFAULT_ESCAPE_HTML = true;
  static final boolean DEFAULT_SERIALIZE_NULLS = false;
  static final boolean DEFAULT_COMPLEX_MAP_KEYS = false;
@@ -179,6 +180,7 @@ public final class Gson {
  final boolean generateNonExecutableJson;
  final boolean htmlSafe;
  final boolean prettyPrinting;
+ final NewlineStyle newlineStyle;
  final boolean lenient;
  final boolean serializeSpecialFloatingPointValues;
  final boolean useJdkUnsafe;
@@ -199,6 +201,8 @@ public final class Gson {
  * <li>The JSON generated by <code>toJson</code> methods is in compact representation. This
  * means that all the unneeded white-space is removed. You can change this behavior with
  * {@link GsonBuilder#setPrettyPrinting()}. </li>
+ * <li>When the JSON generated contains more than one line, the kind of newline to use
+ * can be configured with {@link GsonBuilder#setNewlineStyle(NewlineStyle)}.</li>
  * <li>The generated JSON omits all the fields that are null. Note that nulls in arrays are
  * kept as is since an array is an ordered list. Moreover, if a field is not null, but its
  * generated JSON is empty, the field is kept. You can configure Gson to serialize null values
@@ -230,8 +234,8 @@ public Gson() {
  this(Excluder.DEFAULT, DEFAULT_FIELD_NAMING_STRATEGY,
  Collections.<Type, InstanceCreator<?>>emptyMap(), DEFAULT_SERIALIZE_NULLS,
  DEFAULT_COMPLEX_MAP_KEYS, DEFAULT_JSON_NON_EXECUTABLE, DEFAULT_ESCAPE_HTML,
- DEFAULT_PRETTY_PRINT, DEFAULT_LENIENT, DEFAULT_SPECIALIZE_FLOAT_VALUES,
- DEFAULT_USE_JDK_UNSAFE,
+ DEFAULT_PRETTY_PRINT, DEFAULT_NEWLINE_STYLE, DEFAULT_LENIENT,
+ DEFAULT_SPECIALIZE_FLOAT_VALUES, DEFAULT_USE_JDK_UNSAFE,
  LongSerializationPolicy.DEFAULT, DEFAULT_DATE_PATTERN, DateFormat.DEFAULT, DateFormat.DEFAULT,
  Collections.<TypeAdapterFactory>emptyList(), Collections.<TypeAdapterFactory>emptyList(),
  Collections.<TypeAdapterFactory>emptyList(), DEFAULT_OBJECT_TO_NUMBER_STRATEGY, DEFAULT_NUMBER_TO_NUMBER_STRATEGY,
@@ -241,8 +245,8 @@ public Gson() {
  Gson(Excluder excluder, FieldNamingStrategy fieldNamingStrategy,
  Map<Type, InstanceCreator<?>> instanceCreators, boolean serializeNulls,
  boolean complexMapKeySerialization, boolean generateNonExecutableGson, boolean htmlSafe,
- boolean prettyPrinting, boolean lenient, boolean serializeSpecialFloatingPointValues,
- boolean useJdkUnsafe,
+ boolean prettyPrinting, NewlineStyle newlineStyle, boolean lenient,
+ boolean serializeSpecialFloatingPointValues, boolean useJdkUnsafe,
  LongSerializationPolicy longSerializationPolicy, String datePattern, int dateStyle,
  int timeStyle, List<TypeAdapterFactory> builderFactories,
  List<TypeAdapterFactory> builderHierarchyFactories,
@@ -258,6 +262,7 @@ public Gson() {
  this.generateNonExecutableJson = generateNonExecutableGson;
  this.htmlSafe = htmlSafe;
  this.prettyPrinting = prettyPrinting;
+ this.newlineStyle = newlineStyle;
  this.lenient = lenient;
  this.serializeSpecialFloatingPointValues = serializeSpecialFloatingPointValues;
  this.useJdkUnsafe = useJdkUnsafe;
@@ -876,6 +881,7 @@ public void toJson(JsonElement jsonElement, Appendable writer) throws JsonIOExce
  * <li>{@link GsonBuilder#serializeNulls()}</li>
  * <li>{@link GsonBuilder#setLenient()}</li>
  * <li>{@link GsonBuilder#setPrettyPrinting()}</li>
+ * <li>{@link GsonBuilder#setNewlineStyle(NewlineStyle)}</li>
  * </ul>
  */
  public JsonWriter newJsonWriter(Writer writer) throws IOException {
@@ -886,6 +892,21 @@ public JsonWriter newJsonWriter(Writer writer) throws IOException {
  if (prettyPrinting) {
  jsonWriter.setIndent(" ");
  }
+ switch (newlineStyle) {
+ case CURRENT_OS:
+ jsonWriter.setNewline(System.lineSeparator());
+ break;
+ case WINDOWS:
+ jsonWriter.setNewline("\r\n");
+ break;
+ case OLD_MACOS:
+ jsonWriter.setNewline("\r");
+ break;
+ case MACOS_AND_LINUX: // intentional fallthrough
+ default:
+ jsonWriter.setNewline("\n");
+ break;
+ }
  jsonWriter.setHtmlSafe(htmlSafe);
  jsonWriter.setLenient(lenient);
  jsonWriter.setSerializeNulls(serializeNulls);

gson/src/main/java/com/google/gson/GsonBuilder.java

@@ -24,6 +24,7 @@
 import static com.google.gson.Gson.DEFAULT_NUMBER_TO_NUMBER_STRATEGY;
 import static com.google.gson.Gson.DEFAULT_OBJECT_TO_NUMBER_STRATEGY;
 import static com.google.gson.Gson.DEFAULT_PRETTY_PRINT;
+import static com.google.gson.Gson.DEFAULT_NEWLINE_STYLE;
 import static com.google.gson.Gson.DEFAULT_SERIALIZE_NULLS;
 import static com.google.gson.Gson.DEFAULT_SPECIALIZE_FLOAT_VALUES;
 import static com.google.gson.Gson.DEFAULT_USE_JDK_UNSAFE;
@@ -67,6 +68,7 @@
  * .setDateFormat(DateFormat.LONG)
  * .setFieldNamingPolicy(FieldNamingPolicy.UPPER_CAMEL_CASE)
  * .setPrettyPrinting()
+ * .setNewlineStyle(NewlineStyle.CURRENT_OS)
  * .setVersion(1.0)
  * .create();
  * </pre>
@@ -99,6 +101,7 @@ public final class GsonBuilder {
  private boolean serializeSpecialFloatingPointValues = DEFAULT_SPECIALIZE_FLOAT_VALUES;
  private boolean escapeHtmlChars = DEFAULT_ESCAPE_HTML;
  private boolean prettyPrinting = DEFAULT_PRETTY_PRINT;
+ private NewlineStyle newlineStyle = DEFAULT_NEWLINE_STYLE;
  private boolean generateNonExecutableJson = DEFAULT_JSON_NON_EXECUTABLE;
  private boolean lenient = DEFAULT_LENIENT;
  private boolean useJdkUnsafe = DEFAULT_USE_JDK_UNSAFE;
@@ -130,6 +133,7 @@ public GsonBuilder() {
  this.generateNonExecutableJson = gson.generateNonExecutableJson;
  this.escapeHtmlChars = gson.htmlSafe;
  this.prettyPrinting = gson.prettyPrinting;
+ this.newlineStyle = gson.newlineStyle;
  this.lenient = gson.lenient;
  this.serializeSpecialFloatingPointValues = gson.serializeSpecialFloatingPointValues;
  this.longSerializationPolicy = gson.longSerializationPolicy;
@@ -488,6 +492,17 @@ public GsonBuilder setPrettyPrinting() {
  return this;
  }
 
+ /**
+ * Configures Gson to output Json that uses a certain kind of newline.
+ * This option only affects Json serialization.
+ *
+ * @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
+ */
+ public GsonBuilder setNewlineStyle(NewlineStyle newlineStyle) {
+ this.newlineStyle = newlineStyle;
+ return this;
+ }
+
  /**
  * Configures Gson to allow JSON data which does not strictly comply with the JSON specification.
  *
@@ -761,7 +776,7 @@ public Gson create() {
 
  return new Gson(excluder, fieldNamingPolicy, new HashMap<>(instanceCreators),
  serializeNulls, complexMapKeySerialization,
- generateNonExecutableJson, escapeHtmlChars, prettyPrinting, lenient,
+ generateNonExecutableJson, escapeHtmlChars, prettyPrinting, newlineStyle, lenient,
  serializeSpecialFloatingPointValues, useJdkUnsafe, longSerializationPolicy,
  datePattern, dateStyle, timeStyle, new ArrayList<>(this.factories),
  new ArrayList<>(this.hierarchyFactories), factories,

gson/src/main/java/com/google/gson/NewlineStyle.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2022 Google Inc.
+ *
+ * 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.google.gson;
+
+/**
+ * An enumeration that defines the kind of newline to use for serialization.
+ *
+ * @see <a href="https://en.wikipedia.org/wiki/Newline">Wikipedia Newline article</a>
+ *
+ * @since 2.10.1
+ */
+public enum NewlineStyle {
+ /**
+ * Using this style will result in the same kind of new lines that the current environment uses.
+ *
+ * <p>So it will produce {@code "\r\n"} when running on Windows, and {@code "\n"} when running
+ * on macOS &amp; Linux.</p>
+ */
+ CURRENT_OS,
+
+ /**
+ * Using this style will result in the same new line convention that Windows uses
+ * (and MS-DOS used). This is {@code CR+LF} ({@code 0D 0A}, {@code "\r\n"})
+ */
+ WINDOWS,
+
+ /**
+ * Using this style will result in the same new line convention that macOS, Linux, and UNIX-like
+ * systems use. This is {@code LF} ({@code 0A}, {@code "\n"})
+ */
+ MACOS_AND_LINUX,
+
+ /**
+ * Using this style will result in the same new line convention that classic Mac OS used.
+ * Rarely needed. This is {@code CR} ({@code 0D}, {@code "\r"})
+ */
+ OLD_MACOS;
+}

gson/src/main/java/com/google/gson/stream/JsonWriter.java

@@ -185,6 +185,11 @@ public class JsonWriter implements Closeable, Flushable {
  */
  private String indent;
 
+ /**
+ * A string to be used as newline.
+ */
+ private String newline = "\n";
+
  /**
  * The name/value separator; either ":" or ": ".
  */
@@ -225,6 +230,22 @@ public final void setIndent(String indent) {
  }
  }
 
+ /**
+ * Sets the newline string to be used in the encoded document.
+ *
+ * @param newline the string that will be used for newline.
+ */
+ public final void setNewline(String newline) {
+ this.newline = newline == null ? "\n": newline;
+ }
+
+ /**
+ * Returns the newline string used by this writer.
+ */
+ public final String getNewline() {
+ return newline;
+ }
+
  /**
  * Configure this writer to relax its syntax rules. By default, this writer
  * only emits well-formed JSON as specified by <a
@@ -649,7 +670,7 @@ private void newline() throws IOException {
  return;
  }
 
- out.write('\n');
+ out.write(newline);
  for (int i = 1, size = stackSize; i < size; i++) {
  out.write(indent);
  }

gson/src/test/java/com/google/gson/GsonTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2016 The Gson Authors
+ * Copyright (C) 2022 The Gson Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -57,7 +57,7 @@ public final class GsonTest extends TestCase {
  public void testOverridesDefaultExcluder() {
  Gson gson = new Gson(CUSTOM_EXCLUDER, CUSTOM_FIELD_NAMING_STRATEGY,
  new HashMap<Type, InstanceCreator<?>>(), true, false, true, false,
- true, true, false, true, LongSerializationPolicy.DEFAULT, null, DateFormat.DEFAULT,
+ true,  NewlineStyle.MACOS_AND_LINUX, true, false, true, LongSerializationPolicy.DEFAULT, null, DateFormat.DEFAULT,
  DateFormat.DEFAULT, new ArrayList<TypeAdapterFactory>(),
  new ArrayList<TypeAdapterFactory>(), new ArrayList<TypeAdapterFactory>(),
  CUSTOM_OBJECT_TO_NUMBER_STRATEGY, CUSTOM_NUMBER_TO_NUMBER_STRATEGY,
@@ -72,7 +72,7 @@ public void testOverridesDefaultExcluder() {
  public void testClonedTypeAdapterFactoryListsAreIndependent() {
  Gson original = new Gson(CUSTOM_EXCLUDER, CUSTOM_FIELD_NAMING_STRATEGY,
  new HashMap<Type, InstanceCreator<?>>(), true, false, true, false,
- true, true, false, true, LongSerializationPolicy.DEFAULT, null, DateFormat.DEFAULT,
+ true, NewlineStyle.MACOS_AND_LINUX, true, false, true, LongSerializationPolicy.DEFAULT, null, DateFormat.DEFAULT,
  DateFormat.DEFAULT, new ArrayList<TypeAdapterFactory>(),
  new ArrayList<TypeAdapterFactory>(), new ArrayList<TypeAdapterFactory>(),
  CUSTOM_OBJECT_TO_NUMBER_STRATEGY, CUSTOM_NUMBER_TO_NUMBER_STRATEGY,

gson/src/test/java/com/google/gson/functional/NewlineTest.java

@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2022 Google Inc.
+ *
+ * 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.google.gson.functional;
+
+import java.lang.reflect.Type;
+import java.util.Arrays;
+import java.util.LinkedHashMap;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+
+import junit.framework.TestCase;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.NewlineStyle;
+import com.google.gson.common.TestTypes.ArrayOfObjects;
+import com.google.gson.common.TestTypes.BagOfPrimitives;
+import com.google.gson.reflect.TypeToken;
+
+/**
+ * Functional tests for pretty printing option.
+ *
+ * @author Inderjeet Singh
+ * @author Joel Leitch
+ */
+public class NewlineTest extends TestCase {
+
+ private Map<String, Integer> map;
+ private static final String EXPECTED = "{<EOL> \"abc\": 1,<EOL> \"def\": 5<EOL>}";
+
+ @Override
+ protected void setUp() throws Exception {
+ super.setUp();
+ map = new LinkedHashMap<>();
+ map.put("abc", 1);
+ map.put("def", 5);
+ }
+
+ public void testNewlineDefault() {
+ Gson gson = new GsonBuilder().setPrettyPrinting().create();
+ String json = gson.toJson(map);
+ assertEquals(EXPECTED.replace("<EOL>", "\n"), json);
+ }
+
+ public void testNewlineCrLf() {
+ Gson gson = new GsonBuilder()
+ .setPrettyPrinting()
+ .setNewlineStyle(NewlineStyle.WINDOWS)
+ .create();
+ String json = gson.toJson(map);
+ assertEquals(EXPECTED.replace("<EOL>", "\r\n"), json);
+ }
+
+ public void testNewlineLF() {
+ Gson gson = new GsonBuilder()
+ .setPrettyPrinting()
+ .setNewlineStyle(NewlineStyle.MACOS_AND_LINUX)
+ .create();
+ String json = gson.toJson(map);
+ assertEquals(EXPECTED.replace("<EOL>", "\n"), json);
+ }
+
+ public void testNewlineCr() {
+ Gson gson = new GsonBuilder()
+ .setPrettyPrinting()
+ .setNewlineStyle(NewlineStyle.OLD_MACOS)
+ .create();
+ String json = gson.toJson(map);
+ assertEquals(EXPECTED.replace("<EOL>", "\r"), json);
+ }
+
+ public void testNewlineOS() {
+ Gson gson = new GsonBuilder()
+ .setPrettyPrinting()
+ .setNewlineStyle(NewlineStyle.CURRENT_OS)
+ .create();
+ String json = gson.toJson(map);
+ assertEquals(EXPECTED.replace("<EOL>", System.lineSeparator()), json);
+ }
+
+}

gson/src/test/java/com/google/gson/internal/bind/JsonTreeWriterTest.java

@@ -256,8 +256,12 @@ public void testJsonValue() throws IOException {
  * methods of {@code JsonWriter} must be overridden.
  */
  public void testOverrides() {
- List<String> ignoredMethods = Arrays.asList("setLenient(boolean)", "isLenient()", "setIndent(java.lang.String)",
- "setHtmlSafe(boolean)", "isHtmlSafe()", "setSerializeNulls(boolean)", "getSerializeNulls()");
+ List<String> ignoredMethods = Arrays.asList(
+ "setLenient(boolean)", "isLenient()",
+ "setIndent(java.lang.String)",
+ "setHtmlSafe(boolean)", "isHtmlSafe()",
+ "setNewline(java.lang.String)", "getNewline()",
+ "setSerializeNulls(boolean)", "getSerializeNulls()");
  MoreAsserts.assertOverridesMethods(JsonWriter.class, JsonTreeWriter.class, ignoredMethods);
  }
 }