Replace $Gson$Preconditions.checkNotNull with Objects.requireNonNull (#2180)

* Replace $Gson$Preconditions.checkNotNull with Objects.requireNonNull

* Add back checkNotNull

Author: Marcono1234

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

@@ -16,12 +16,12 @@
 
 package com.google.gson;
 
-import com.google.gson.internal.$Gson$Preconditions;
 import java.lang.annotation.Annotation;
 import java.lang.reflect.Field;
 import java.lang.reflect.Type;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.Objects;
 
 /**
  * A data object that stores attributes of a field.
@@ -42,8 +42,7 @@ public final class FieldAttributes {
    * @param f the field to pull attributes from
    */
   public FieldAttributes(Field f) {
-    $Gson$Preconditions.checkNotNull(f);
-    this.field = f;
+    this.field = Objects.requireNonNull(f);
   }
 
   /**

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

@@ -54,6 +54,7 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.atomic.AtomicLong;
@@ -504,9 +505,7 @@ private static TypeAdapter<AtomicLongArray> atomicLongArrayAdapter(final TypeAda
    */
   @SuppressWarnings("unchecked")
   public <T> TypeAdapter<T> getAdapter(TypeToken<T> type) {
-    if (type == null) {
-      throw new NullPointerException("type must not be null");
-    }
+    Objects.requireNonNull(type, "type must not be null");
     TypeAdapter<?> cached = typeTokenCache.get(type);
     if (cached != null) {
       return (TypeAdapter<T>) cached;

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

@@ -16,26 +16,6 @@
 
 package com.google.gson;
 
-import java.lang.reflect.Type;
-import java.text.DateFormat;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.Date;
-import java.util.HashMap;
-import java.util.LinkedList;
-import java.util.List;
-import java.util.Map;
-
-import com.google.gson.internal.$Gson$Preconditions;
-import com.google.gson.internal.Excluder;
-import com.google.gson.internal.bind.DefaultDateTypeAdapter;
-import com.google.gson.internal.bind.TreeTypeAdapter;
-import com.google.gson.internal.bind.TypeAdapters;
-import com.google.gson.internal.sql.SqlTypesSupport;
-import com.google.gson.reflect.TypeToken;
-import com.google.gson.stream.JsonReader;
-import com.google.gson.stream.JsonWriter;
-
 import static com.google.gson.Gson.DEFAULT_COMPLEX_MAP_KEYS;
 import static com.google.gson.Gson.DEFAULT_DATE_PATTERN;
 import static com.google.gson.Gson.DEFAULT_ESCAPE_HTML;
@@ -48,6 +28,26 @@
 import static com.google.gson.Gson.DEFAULT_SPECIALIZE_FLOAT_VALUES;
 import static com.google.gson.Gson.DEFAULT_USE_JDK_UNSAFE;
 
+import com.google.gson.internal.$Gson$Preconditions;
+import com.google.gson.internal.Excluder;
+import com.google.gson.internal.bind.DefaultDateTypeAdapter;
+import com.google.gson.internal.bind.TreeTypeAdapter;
+import com.google.gson.internal.bind.TypeAdapters;
+import com.google.gson.internal.sql.SqlTypesSupport;
+import com.google.gson.reflect.TypeToken;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+import java.lang.reflect.Type;
+import java.text.DateFormat;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Date;
+import java.util.HashMap;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+
 /**
  * <p>Use this builder to construct a {@link Gson} instance when you need to set configuration
  * options other than the default. For {@link Gson} with default configuration, it is simpler to
@@ -166,7 +166,7 @@ public GsonBuilder setVersion(double ignoreVersionsAfter) {
    * @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
    */
   public GsonBuilder excludeFieldsWithModifiers(int... modifiers) {
-    $Gson$Preconditions.checkNotNull(modifiers);
+    Objects.requireNonNull(modifiers);
     excluder = excluder.withModifiers(modifiers);
     return this;
   }
@@ -310,8 +310,7 @@ public GsonBuilder disableInnerClassSerialization() {
    * @since 1.3
    */
   public GsonBuilder setLongSerializationPolicy(LongSerializationPolicy serializationPolicy) {
-    $Gson$Preconditions.checkNotNull(serializationPolicy);
-    this.longSerializationPolicy = serializationPolicy;
+    this.longSerializationPolicy = Objects.requireNonNull(serializationPolicy);
     return this;
   }
 
@@ -334,8 +333,7 @@ public GsonBuilder setFieldNamingPolicy(FieldNamingPolicy namingConvention) {
    * @since 1.3
    */
   public GsonBuilder setFieldNamingStrategy(FieldNamingStrategy fieldNamingStrategy) {
-    $Gson$Preconditions.checkNotNull(fieldNamingStrategy);
-    this.fieldNamingPolicy = fieldNamingStrategy;
+    this.fieldNamingPolicy = Objects.requireNonNull(fieldNamingStrategy);
     return this;
   }
 
@@ -347,8 +345,7 @@ public GsonBuilder setFieldNamingStrategy(FieldNamingStrategy fieldNamingStrateg
    * @see ToNumberPolicy#DOUBLE The default object-to-number strategy
    */
   public GsonBuilder setObjectToNumberStrategy(ToNumberStrategy objectToNumberStrategy) {
-    $Gson$Preconditions.checkNotNull(objectToNumberStrategy);
-    this.objectToNumberStrategy = objectToNumberStrategy;
+    this.objectToNumberStrategy = Objects.requireNonNull(objectToNumberStrategy);
     return this;
   }
 
@@ -360,8 +357,7 @@ public GsonBuilder setObjectToNumberStrategy(ToNumberStrategy objectToNumberStra
    * @see ToNumberPolicy#LAZILY_PARSED_NUMBER The default number-to-number strategy
    */
   public GsonBuilder setNumberToNumberStrategy(ToNumberStrategy numberToNumberStrategy) {
-    $Gson$Preconditions.checkNotNull(numberToNumberStrategy);
-    this.numberToNumberStrategy = numberToNumberStrategy;
+    this.numberToNumberStrategy = Objects.requireNonNull(numberToNumberStrategy);
     return this;
   }
 
@@ -378,7 +374,7 @@ public GsonBuilder setNumberToNumberStrategy(ToNumberStrategy numberToNumberStra
    * @since 1.4
    */
   public GsonBuilder setExclusionStrategies(ExclusionStrategy... strategies) {
-    $Gson$Preconditions.checkNotNull(strategies);
+    Objects.requireNonNull(strategies);
     for (ExclusionStrategy strategy : strategies) {
       excluder = excluder.withExclusionStrategy(strategy, true, true);
     }
@@ -398,7 +394,7 @@ public GsonBuilder setExclusionStrategies(ExclusionStrategy... strategies) {
    * @since 1.7
    */
   public GsonBuilder addSerializationExclusionStrategy(ExclusionStrategy strategy) {
-    $Gson$Preconditions.checkNotNull(strategy);
+    Objects.requireNonNull(strategy);
     excluder = excluder.withExclusionStrategy(strategy, true, false);
     return this;
   }
@@ -416,7 +412,7 @@ public GsonBuilder addSerializationExclusionStrategy(ExclusionStrategy strategy)
    * @since 1.7
    */
   public GsonBuilder addDeserializationExclusionStrategy(ExclusionStrategy strategy) {
-    $Gson$Preconditions.checkNotNull(strategy);
+    Objects.requireNonNull(strategy);
     excluder = excluder.withExclusionStrategy(strategy, false, true);
     return this;
   }
@@ -547,7 +543,7 @@ public GsonBuilder setDateFormat(int dateStyle, int timeStyle) {
    */
   @SuppressWarnings({"unchecked", "rawtypes"})
   public GsonBuilder registerTypeAdapter(Type type, Object typeAdapter) {
-    $Gson$Preconditions.checkNotNull(type);
+    Objects.requireNonNull(type);
     $Gson$Preconditions.checkArgument(typeAdapter instanceof JsonSerializer<?>
         || typeAdapter instanceof JsonDeserializer<?>
         || typeAdapter instanceof InstanceCreator<?>
@@ -574,7 +570,7 @@ public GsonBuilder registerTypeAdapter(Type type, Object typeAdapter) {
    * @since 2.1
    */
   public GsonBuilder registerTypeAdapterFactory(TypeAdapterFactory factory) {
-    $Gson$Preconditions.checkNotNull(factory);
+    Objects.requireNonNull(factory);
     factories.add(factory);
     return this;
   }
@@ -595,7 +591,7 @@ public GsonBuilder registerTypeAdapterFactory(TypeAdapterFactory factory) {
    */
   @SuppressWarnings({"unchecked", "rawtypes"})
   public GsonBuilder registerTypeHierarchyAdapter(Class<?> baseType, Object typeAdapter) {
-    $Gson$Preconditions.checkNotNull(baseType);
+    Objects.requireNonNull(baseType);
     $Gson$Preconditions.checkArgument(typeAdapter instanceof JsonSerializer<?>
         || typeAdapter instanceof JsonDeserializer<?>
         || typeAdapter instanceof TypeAdapter<?>);
@@ -669,7 +665,7 @@ public GsonBuilder disableJdkUnsafe() {
    * @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
    */
   public GsonBuilder addReflectionAccessFilter(ReflectionAccessFilter filter) {
-    $Gson$Preconditions.checkNotNull(filter);
+    Objects.requireNonNull(filter);
     reflectionFilters.addFirst(filter);
     return this;
   }

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

@@ -16,10 +16,10 @@
 
 package com.google.gson;
 
-import com.google.gson.internal.$Gson$Preconditions;
 import com.google.gson.internal.LazilyParsedNumber;
 import java.math.BigDecimal;
 import java.math.BigInteger;
+import java.util.Objects;
 
 /**
  * A class representing a JSON primitive value. A primitive value
@@ -40,7 +40,7 @@ public final class JsonPrimitive extends JsonElement {
    */
   @SuppressWarnings("deprecation") // superclass constructor
   public JsonPrimitive(Boolean bool) {
-    value = $Gson$Preconditions.checkNotNull(bool);
+    value = Objects.requireNonNull(bool);
   }
 
   /**
@@ -50,7 +50,7 @@ public JsonPrimitive(Boolean bool) {
    */
   @SuppressWarnings("deprecation") // superclass constructor
   public JsonPrimitive(Number number) {
-    value = $Gson$Preconditions.checkNotNull(number);
+    value = Objects.requireNonNull(number);
   }
 
   /**
@@ -60,7 +60,7 @@ public JsonPrimitive(Number number) {
    */
   @SuppressWarnings("deprecation") // superclass constructor
   public JsonPrimitive(String string) {
-    value = $Gson$Preconditions.checkNotNull(string);
+    value = Objects.requireNonNull(string);
   }
 
   /**
@@ -73,7 +73,7 @@ public JsonPrimitive(String string) {
   public JsonPrimitive(Character c) {
     // convert characters to strings since in JSON, characters are represented as a single
     // character string
-    value = $Gson$Preconditions.checkNotNull(c).toString();
+    value = Objects.requireNonNull(c).toString();
   }
 
   /**

gson/src/main/java/com/google/gson/internal/$Gson$Preconditions.java

@@ -16,6 +16,8 @@
 
 package com.google.gson.internal;
 
+import java.util.Objects;
+
 /**
  * A simple utility class used to check method Preconditions.
  *
@@ -34,6 +36,12 @@ public final class $Gson$Preconditions {
     throw new UnsupportedOperationException();
   }
 
+  /**
+   * @deprecated
+   * This is an internal Gson method. Use {@link Objects#requireNonNull(Object)} instead.
+   */
+  // Only deprecated for now because external projects might be using this by accident
+  @Deprecated
   public static <T> T checkNotNull(T obj) {
     if (obj == null) {
       throw new NullPointerException();

gson/src/main/java/com/google/gson/internal/$Gson$Types.java

@@ -17,7 +17,7 @@
 package com.google.gson.internal;
 
 import static com.google.gson.internal.$Gson$Preconditions.checkArgument;
-import static com.google.gson.internal.$Gson$Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
 
 import java.io.Serializable;
 import java.lang.reflect.Array;
@@ -486,7 +486,7 @@ private static final class ParameterizedTypeImpl implements ParameterizedType, S
     private final Type[] typeArguments;
 
     public ParameterizedTypeImpl(Type ownerType, Type rawType, Type... typeArguments) {
-      checkNotNull(rawType);
+      requireNonNull(rawType);
       // require an owner type if the raw type needs it
       if (rawType instanceof Class<?>) {
         Class<?> rawTypeAsClass = (Class<?>) rawType;
@@ -499,7 +499,7 @@ public ParameterizedTypeImpl(Type ownerType, Type rawType, Type... typeArguments
       this.rawType = canonicalize(rawType);
       this.typeArguments = typeArguments.clone();
       for (int t = 0, length = this.typeArguments.length; t < length; t++) {
-        checkNotNull(this.typeArguments[t]);
+        requireNonNull(this.typeArguments[t]);
         checkNotPrimitive(this.typeArguments[t]);
         this.typeArguments[t] = canonicalize(this.typeArguments[t]);
       }
@@ -553,7 +553,7 @@ private static final class GenericArrayTypeImpl implements GenericArrayType, Ser
     private final Type componentType;
 
     public GenericArrayTypeImpl(Type componentType) {
-      checkNotNull(componentType);
+      requireNonNull(componentType);
       this.componentType = canonicalize(componentType);
     }
 
@@ -592,14 +592,14 @@ public WildcardTypeImpl(Type[] upperBounds, Type[] lowerBounds) {
       checkArgument(upperBounds.length == 1);
 
       if (lowerBounds.length == 1) {
-        checkNotNull(lowerBounds[0]);
+        requireNonNull(lowerBounds[0]);
         checkNotPrimitive(lowerBounds[0]);
         checkArgument(upperBounds[0] == Object.class);
         this.lowerBound = canonicalize(lowerBounds[0]);
         this.upperBound = Object.class;
 
       } else {
-        checkNotNull(upperBounds[0]);
+        requireNonNull(upperBounds[0]);
         checkNotPrimitive(upperBounds[0]);
         this.lowerBound = null;
         this.upperBound = canonicalize(upperBounds[0]);

gson/src/main/java/com/google/gson/internal/Streams.java

@@ -28,6 +28,7 @@
 import java.io.EOFException;
 import java.io.IOException;
 import java.io.Writer;
+import java.util.Objects;
 
 /**
  * Reads and writes GSON parse trees over streams.
@@ -105,7 +106,7 @@ private static final class AppendableWriter extends Writer {
 
     @Override public void write(String str, int off, int len) throws IOException {
       // Appendable.append turns null -> "null", which is not desired here
-      $Gson$Preconditions.checkNotNull(str);
+      Objects.requireNonNull(str);
       appendable.append(str, off, off + len);
     }
 

gson/src/main/java/com/google/gson/internal/bind/ArrayTypeAdapter.java

@@ -16,13 +16,6 @@
 
 package com.google.gson.internal.bind;
 
-import java.io.IOException;
-import java.lang.reflect.Array;
-import java.lang.reflect.GenericArrayType;
-import java.lang.reflect.Type;
-import java.util.ArrayList;
-import java.util.List;
-
 import com.google.gson.Gson;
 import com.google.gson.TypeAdapter;
 import com.google.gson.TypeAdapterFactory;
@@ -31,6 +24,11 @@
 import com.google.gson.stream.JsonReader;
 import com.google.gson.stream.JsonToken;
 import com.google.gson.stream.JsonWriter;
+import java.io.IOException;
+import java.lang.reflect.Array;
+import java.lang.reflect.GenericArrayType;
+import java.lang.reflect.Type;
+import java.util.ArrayList;
 
 /**
  * Adapt an array of objects.