Update Precondition checks and have it throw a NPE instead.

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

@@ -48,8 +48,7 @@ class DelegatingJsonElementVisitor implements JsonElementVisitor {
   private final JsonElementVisitor delegate;
 
   protected DelegatingJsonElementVisitor(JsonElementVisitor delegate) {
-    Preconditions.checkNotNull(delegate);
-    this.delegate = delegate;
+    this.delegate = Preconditions.checkNotNull(delegate);
   }
 
   public void endArray(JsonArray array) throws IOException {

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

@@ -28,8 +28,7 @@ final class DisjunctionExclusionStrategy implements ExclusionStrategy {
   private final Collection<ExclusionStrategy> strategies;
 
   DisjunctionExclusionStrategy(Collection<ExclusionStrategy> strategies) {
-    Preconditions.checkNotNull(strategies);
-    this.strategies = strategies;
+    this.strategies = Preconditions.checkNotNull(strategies);
   }
 
   public boolean shouldSkipField(FieldAttributes f) {

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

@@ -57,13 +57,12 @@ public final class FieldAttributes {
    * @param f the field to pull attributes from
    */
   FieldAttributes(final Class<?> declaringClazz, final Field f) {
-    Preconditions.checkNotNull(declaringClazz);
-    this.declaringClazz = declaringClazz;
-    name = f.getName();
-    declaredType = f.getType();
-    isSynthetic = f.isSynthetic();
-    modifiers = f.getModifiers();
-    field = f;
+    this.declaringClazz = Preconditions.checkNotNull(declaringClazz);
+    this.name = f.getName();
+    this.declaredType = f.getType();
+    this.isSynthetic = f.isSynthetic();
+    this.modifiers = f.getModifiers();
+    this.field = f;
   }
 
   private static int getMaxCacheSize() {

gson/src/main/java/com/google/gson/FieldNamingStrategy2Adapter.java

@@ -28,8 +28,7 @@ final class FieldNamingStrategy2Adapter implements FieldNamingStrategy2 {
   private final FieldNamingStrategy adaptee;
 
   public FieldNamingStrategy2Adapter(FieldNamingStrategy adaptee) {
-    Preconditions.checkNotNull(adaptee);
-    this.adaptee = adaptee;
+    this.adaptee = Preconditions.checkNotNull(adaptee);
   }
 
   public String translateName(FieldAttributes f) {

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

@@ -364,8 +364,8 @@ public final class GsonBuilder {
    * @since 1.7
    */
   public GsonBuilder setExclusionStrategies(Mode mode, ExclusionStrategy... strategies) {
-    Preconditions.checkNotNull(mode);
-    Set<ExclusionStrategy> strategySet = (mode == Mode.SERIALIZE) 
+    Set<ExclusionStrategy> strategySet = 
+        (Preconditions.checkNotNull(mode) == Mode.SERIALIZE) 
         ? serializeExclusionStrategies : deserializeExclusionStrategies;
     strategySet.addAll(Arrays.asList(strategies));
     return this;

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

@@ -41,12 +41,11 @@ abstract class JsonDeserializationVisitor<T> implements ObjectNavigator.Visitor
       ObjectNavigatorFactory factory, ObjectConstructor objectConstructor,
       ParameterizedTypeHandlerMap<JsonDeserializer<?>> deserializers,
       JsonDeserializationContext context) {
-    Preconditions.checkNotNull(json);
     this.targetType = targetType;
     this.factory = factory;
     this.objectConstructor = objectConstructor;
     this.deserializers = deserializers;
-    this.json = json;
+    this.json = Preconditions.checkNotNull(json);
     this.context = context;
     this.constructed = false;
   }

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

@@ -40,8 +40,7 @@ class JsonDeserializerExceptionWrapper<T> implements JsonDeserializer<T> {
    * @throws IllegalArgumentException if {@code delegate} is {@code null}.
    */
   JsonDeserializerExceptionWrapper(JsonDeserializer<T> delegate) {
-    Preconditions.checkNotNull(delegate);
-    this.delegate = delegate;
+    this.delegate = Preconditions.checkNotNull(delegate);
   }
 
   public T deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)

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

@@ -52,11 +52,10 @@ public final class JsonObject extends JsonElement {
    * @param value the member object.
    */
   public void add(String property, JsonElement value) {
-    Preconditions.checkNotNull(property);
     if (value == null) {
       value = JsonNull.createJsonNull();
     }
-    members.put(property, value);
+    members.put(Preconditions.checkNotNull(property), value);
   }
 
   /**

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

@@ -211,8 +211,7 @@ final class JsonSerializationVisitor implements ObjectNavigator.Visitor {
   }
 
   private void assignToRoot(JsonElement newRoot) {
-    Preconditions.checkNotNull(newRoot);
-    root = newRoot;
+    root = Preconditions.checkNotNull(newRoot);
   }
 
   private boolean isFieldNull(FieldAttributes f, Object obj) {

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

@@ -36,7 +36,6 @@ final class MemoryRefStack {
    */
   public ObjectTypePair push(ObjectTypePair obj) {
     Preconditions.checkNotNull(obj);
-
     return stack.push(obj);
   }
 

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

@@ -63,8 +63,7 @@ final class ModifyFirstLetterNamingPolicy extends RecursiveFieldNamingPolicy {
    * @throws IllegalArgumentException if {@code modifier} is null
    */
   ModifyFirstLetterNamingPolicy(LetterModifier modifier) {
-    Preconditions.checkNotNull(modifier);
-    this.letterModifier = modifier;
+    this.letterModifier = Preconditions.checkNotNull(modifier);
   }
 
   @Override

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

@@ -88,10 +88,8 @@ final class ObjectNavigator {
    *          object.
    */
   ObjectNavigator(ObjectTypePair objTypePair, ExclusionStrategy exclusionStrategy) {
-    Preconditions.checkNotNull(exclusionStrategy);
-
     this.objTypePair = objTypePair;
-    this.exclusionStrategy = exclusionStrategy;
+    this.exclusionStrategy = Preconditions.checkNotNull(exclusionStrategy);
   }
 
   /**

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

@@ -37,9 +37,8 @@ final class ObjectNavigatorFactory {
    *        names
    */
   public ObjectNavigatorFactory(ExclusionStrategy strategy, FieldNamingStrategy2 fieldNamingPolicy) {
-    Preconditions.checkNotNull(fieldNamingPolicy);
     this.strategy = (strategy == null ? new NullExclusionStrategy() : strategy);
-    this.fieldNamingPolicy = fieldNamingPolicy;
+    this.fieldNamingPolicy = Preconditions.checkNotNull(fieldNamingPolicy);
   }
 
   /**

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

@@ -31,7 +31,9 @@ package com.google.gson;
  */
 final class Preconditions {
   public static <T> T checkNotNull(T obj) {
-    checkArgument(obj != null);
+    if (obj == null) {
+      throw new NullPointerException();
+    }
     return obj;
   }
 

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

@@ -76,12 +76,8 @@ final class Primitives {
    * @see Class#isPrimitive
    */
   public static boolean isWrapperType(Class<?> type) {
-    return WRAPPER_TO_PRIMITIVE_TYPE.containsKey(checkNotNull(type));
-  }
-
-  private static Class<?> checkNotNull(Class<?> type) {
-    Preconditions.checkNotNull(type);
-    return type;
+    return WRAPPER_TO_PRIMITIVE_TYPE.containsKey(
+        Preconditions.checkNotNull(type));
   }
 
   /**
@@ -94,11 +90,10 @@ final class Primitives {
    * </pre>
    */
   public static <T> Class<T> wrap(Class<T> type) {
-    checkNotNull(type);
-
     // cast is safe: long.class and Long.class are both of type Class<Long>
     @SuppressWarnings("unchecked")
-    Class<T> wrapped = (Class<T>) PRIMITIVE_TO_WRAPPER_TYPE.get(type);
+    Class<T> wrapped = (Class<T>) PRIMITIVE_TO_WRAPPER_TYPE.get(
+        Preconditions.checkNotNull(type));
     return (wrapped == null) ? type : wrapped;
   }
 
@@ -112,11 +107,10 @@ final class Primitives {
    * </pre>
    */
   public static <T> Class<T> unwrap(Class<T> type) {
-    checkNotNull(type);
-
     // cast is safe: long.class and Long.class are both of type Class<Long>
     @SuppressWarnings("unchecked")
-    Class<T> unwrapped = (Class<T>) WRAPPER_TO_PRIMITIVE_TYPE.get(type);
+    Class<T> unwrapped = (Class<T>) WRAPPER_TO_PRIMITIVE_TYPE.get(
+        Preconditions.checkNotNull(type));
     return (unwrapped == null) ? type : unwrapped;
   }  
 }

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

@@ -30,7 +30,6 @@ import java.util.Collection;
 abstract class RecursiveFieldNamingPolicy implements FieldNamingStrategy2 {
 
   public final String translateName(FieldAttributes f) {
-    Preconditions.checkNotNull(f);
     return translateName(f.getName(), f.getDeclaredType(), f.getAnnotations());
   }
 

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

@@ -40,7 +40,6 @@ final class SerializedNameAnnotationInterceptingNamingPolicy implements FieldNam
   }
 
   public String translateName(FieldAttributes f) {
-    Preconditions.checkNotNull(f);
     SerializedName serializedName = f.getAnnotation(SerializedName.class);
     return serializedName == null ? delegate.translateName(f)
         : fieldNameValidator.validate(serializedName.value());

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

@@ -33,7 +33,7 @@ public class CamelCaseSeparatorNamingPolicyTest extends TestCase {
     try {
       new CamelCaseSeparatorNamingPolicy(null);
       fail("Null separator string is not supported");
-    } catch (IllegalArgumentException expected) { }
+    } catch (NullPointerException expected) { }
 
     try {
       new CamelCaseSeparatorNamingPolicy("");

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

@@ -41,7 +41,7 @@ public class DisjunctionExclusionStrategyTest extends TestCase {
       List<ExclusionStrategy> constructorParam = null;
       new DisjunctionExclusionStrategy(constructorParam);
       fail("Should throw an exception");
-    } catch (IllegalArgumentException expected) { }
+    } catch (NullPointerException expected) { }
   }
 
   public void testSkipFieldsWithMixedTrueAndFalse() throws Exception {

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

@@ -42,6 +42,6 @@ public class JavaFieldNamingPolicyTest extends TestCase {
     try {
       namingPolicy.translateName((FieldAttributes) null);
       fail("Should have thrown an exception");
-    } catch (IllegalArgumentException expected) { }
+    } catch (NullPointerException expected) { }
   }
 }

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

@@ -58,7 +58,7 @@ public class JsonObjectTest extends TestCase {
     try {
       jsonObj.add(null, JsonNull.createJsonNull());
       fail("Should not allow null property names.");
-    } catch (IllegalArgumentException expected) { }
+    } catch (NullPointerException expected) { }
 
     jsonObj.add("", JsonNull.createJsonNull());
     jsonObj.add("   \t", JsonNull.createJsonNull());

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

@@ -29,7 +29,7 @@ public class ModifyFirstLetterNamingPolicyTest extends TestCase {
     try {
       new ModifyFirstLetterNamingPolicy(null);
       fail("Null values are not allowed as a constructor parameters");
-    } catch (IllegalArgumentException expected) { }
+    } catch (NullPointerException expected) { }
   }
 
   public void testLowerCaseFirstLetter() throws Exception {