com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was STRING at line 1 column 1 path $ at com.google.gson.Gson.fromJson(Gson.java:826) at com.google.gson.Gson.fromJson(Gson.java:779) at com.google.gson.Gson.fromJson(Gson.java:728) at readtv.ghs.tv.util.RewardRuleUtil$1.onSuccess(RewardRuleUtil.java:63) at readtv.ghs.tv.http.AsyncHttpClient$2$2.run(AsyncHttpClient.java:116) at android.os.Handler.handleCallback(Handler.java:733) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:136) at android.app.ActivityThread.main(ActivityThread.java:5013) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:515) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:811) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:627) Caused by: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was STRING at line 1 column 1 path $ at com.google.gson.stream.JsonReader.beginArray(JsonReader.java:350) at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:79) at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:60) at com.google.gson.Gson.fromJson(Gson.java:814) ... 12 more java.lang.IllegalStateException: Expected BEGIN_ARRAY but was STRING at line 1 column 1 path $ at com.google.gson.stream.JsonReader.beginArray(JsonReader.java:350) at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:79) at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:60) at com.google.gson.Gson.fromJson(Gson.java:814) at com.google.gson.Gson.fromJson(Gson.java:779) at com.google.gson.Gson.fromJson(Gson.java:728) at readtv.ghs.tv.util.RewardRuleUtil$1.onSuccess(RewardRuleUtil.java:63) at readtv.ghs.tv.http.AsyncHttpClient$2$2.run(AsyncHttpClient.java:116) at android.os.Handler.handleCallback(Handler.java:733) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:136) at android.app.ActivityThread.main(ActivityThread.java:5013) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:515) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:811) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:627)

Often this kind of problem, I hope you can tell me how to deal with the simple. Or where it is. I don't think it's our problem.

I'm getting this crash lately. It complains about SerializedName class missing the "value" method.

This is the stacktrace:

java.lang.IncompatibleClassChangeError: Couldn't find com.google.gson.annotations.SerializedName.value
at libcore.reflect.AnnotationAccess.toAnnotationInstance(AnnotationAccess.java:659)
at libcore.reflect.AnnotationAccess.toAnnotationInstance(AnnotationAccess.java:641)
at libcore.reflect.AnnotationAccess.getDeclaredAnnotation(AnnotationAccess.java:170)
at java.lang.reflect.Field.getAnnotation(Field.java:242)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getFieldName(ReflectiveTypeAdapterFactory.java:71)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getFieldName(ReflectiveTypeAdapterFactory.java:67)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:142)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:83)
at com.google.gson.Gson.getAdapter(Gson.java:359)
at com.google.gson.internal.bind.CollectionTypeAdapterFactory.create(CollectionTypeAdapterFactory.java:52)
at com.google.gson.Gson.getAdapter(Gson.java:359)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getFieldAdapter(ReflectiveTypeAdapterFactory.java:122)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.access$100(ReflectiveTypeAdapterFactory.java:46)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.(ReflectiveTypeAdapterFactory.java:92)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:91)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:142)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:83)
at com.google.gson.Gson.getAdapter(Gson.java:359)
at com.google.gson.Gson.fromJson(Gson.java:809)
at com.google.gson.Gson.fromJson(Gson.java:875)
at com.google.gson.Gson.fromJson(Gson.java:848)

D/Retrofit﹕java.lang.SecurityException: Can't make field constructor accessible
            at java.lang.reflect.Constructor.setAccessible(Constructor.java:334)
            at com.google.gson.internal.ConstructorConstructor.newDefaultConstructor(ConstructorConstructor.java:97)
            at com.google.gson.internal.ConstructorConstructor.get(ConstructorConstructor.java:79)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:82)
            at com.google.gson.Gson.getAdapter(Gson.java:359)
            at com.google.gson.internal.bind.CollectionTypeAdapterFactory.create(CollectionTypeAdapterFactory.java:52)
            at com.google.gson.Gson.getAdapter(Gson.java:359)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getFieldAdapter(ReflectiveTypeAdapterFactory.java:122)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.access$100(ReflectiveTypeAdapterFactory.java:46)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.<init>(ReflectiveTypeAdapterFactory.java:92)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:91)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:142)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:83)
            at com.google.gson.Gson.getAdapter(Gson.java:359)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getFieldAdapter(ReflectiveTypeAdapterFactory.java:122)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.access$100(ReflectiveTypeAdapterFactory.java:46)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.<init>(ReflectiveTypeAdapterFactory.java:92)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:91)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:142)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:83)
            at com.google.gson.Gson.getAdapter(Gson.java:359)
            at com.google.gson.internal.bind.CollectionTypeAdapterFactory.create(CollectionTypeAdapterFactory.java:52)
            at com.google.gson.Gson.getAdapter(Gson.java:359)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getFieldAdapter(ReflectiveTypeAdapterFactory.java:122)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.access$100(ReflectiveTypeAdapterFactory.java:46)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.<init>(ReflectiveTypeAdapterFactory.java:92)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:91)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:142)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:83)
            at com.google.gson.Gson.getAdapter(Gson.java:359)
            at com.google.gson.Gson.fromJson(Gson.java:809)
            at com.google.gson.Gson.fromJson(Gson.java:775)
            at retrofit.converter.GsonConverter.fromBody(GsonConverter.java:63)
            at retrofit.RestAdapter$RestHandler.invokeRequest(RestAdapter.java:367)
            at retrofit.RestAdapter$RestHandler.access$100(RestAdapter.java:220)
            at retrofit.RestAdapter$RestHandler$2.obtainResponse(RestAdapter.java:278)
            at retrofit.CallbackRunnable.run(CallbackRunnable.java:42)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
            at retrofit.Platform$Android$2$1.run(Platform.java:142)
            at java.lang.Thread.run(Thread.java:818)

Originally filed at https://github.com/square/retrofit/issues/870.

Note: this might be a bug in the preview OS runtime and not Gson, but it's definitely not a Retrofit problem.

Gson shouldn't cast a number to a Double if a number does not have decimal digits. It's clearly wrong.

public class GsonVsJackson {


    public static void main(String[] args) throws Exception {
        testGson();
        System.out.println("========================");
        testJackson();
    }

    public static void testGson() {
        System.out.println("Testing Gson 2.8");
        Gson gson = new Gson();
        HashMap<String, Object> newTest = new HashMap<>();
        newTest.put("first", 6906764140092371368L);
        String jsonString = gson.toJson(newTest);
        System.out.println(jsonString); // output ok: {"first":6906764140092371368}
        Map<String, Object> mapFromJson = gson.fromJson(jsonString, Map.class);
        Number numberFromJson = (Number) mapFromJson.get("first");
        System.out.println(numberFromJson.getClass() + " = " + numberFromJson); // java.lang.Double val 6.9067641400923709E18
        long longVal = numberFromJson.longValue();
        System.out.println(longVal); // output rounded: 6906764140092370944
    }

    public static void testJackson() throws Exception {
        System.out.println("Testing Jackson");
        ObjectMapper jackson = new ObjectMapper();
        HashMap<String, Object> newTest = new HashMap<>();
        newTest.put("first", 6906764140092371368L);
        String jsonString = jackson.writeValueAsString(newTest);
        System.out.println(jsonString); // output ok: {"first":6906764140092371368}
        Map<String, Object> mapFromJson = jackson.readValue(jsonString, Map.class);
        Number numberFromJson = (Number) mapFromJson.get("first");
        System.out.println(numberFromJson.getClass() + " = " + numberFromJson); // java.math.BigInteger = 6906764140092371368
        long longVal = numberFromJson.longValue();
        System.out.println(longVal); // output OK: 6906764140092371368
    }

}

Kind Regards, Daniele

What steps will reproduce the problem?
1. Use on web application / Tomcat , view log
2.
3.

What is the expected output? What do you see instead?
Expected None / Warning

What version of the product are you using? On what operating system?
CentOS/ Apache Tomcat Version 7.0.12

Please provide any additional information below.

Jan 26, 2012 12:09:41 AM org.apache.catalina.loader.WebappClassLoader 
checkThreadLocalMapForLeaks
SEVERE: The web application [] created a ThreadLocal with key of type 
[com.google.gson.internal.bind.MiniGson$1] (value 
[com.google.gson.internal.bind.MiniGson$1@73055179]) and a value of type 
[java.util.HashMap] (value [{}]) but failed to remove it when the web 
application was stopped. Threads are going to be renewed over time to try and 
avoid a probable memory leak.

Original issue reported on code.google.com by [email protected] on 26 Jan 2012 at 6:17

What steps will reproduce the problem?

1. Create a simple *non-static* class which initializes default values for some 
fields:

    public class Test {

        int x = -1;
        String s = "Hello";
    }

2. Create new Gson and call `fromJson()` with missing fields:

    Test t = new Gson().fromJson("{}", Test.class);
    System.out.println(String.format("x=[%s] s=[%s]", t.x, t.s));

>> Results: x=[0] s=[null]

    Test t = new Gson().fromJson("{\"x\": 1}", Test.class);
    System.out.println(String.format("x=[%s] s=[%s]", t.x, t.s));

>> Results: x=[1] s=[null]

What is the expected output? What do you see instead?

As the test cases, I would like to expect default value for each field to be 
the one that the class initializes. For instance with the first test case, `x` 
should be `-1` and `s` should be "Hello".

What version of the product are you using? On what operating system?

 - Gson 2.2.3
 - OSes:
   + Fedora 18, 64 bit with OpenJDK 1.7.0_19;
   + Android API 4 and API 17;

Thanks,
Hai

Original issue reported on code.google.com by [email protected] on 5 May 2013 at 8:23

RFC 8259, 6 Numbers allows numbers of arbitrary range and precision specifying that a particular implementation may set some limits for numeric values. As of Gson 2.8.4 uses the following deserialization strategies:

• If the result type is declared as Object, Gson always returns Doubles for all encountered JSON numbers. In this case, the minimum and maximum hold number value fits the limits of Double which cannot hold exact Long values that exceed the Double exact precision limits (2^53+1).
• ‎If the result type is declared as Number and there are no custom Number adapters, Gson always returns LazilyParsedNumbers that hold original string values parsing them to a requested type lazily allowing to use the whole range of Long. However, it does not allow to use numbers of arbitrary range and precision, and does not expose its hold string as a BigDecimal.

In order to fix these limitations and preserve backwards compatibility, some sort of "to-number" strategies might be accepted in GsonBuilder to override the default behavior of Gson. This pull-request introduces such a strategy interface to be used in the built-in Object and Number type adapters. There are also four strategies implemented in this PR (two standard to keep the backwards compatibility and two enhanced to overcome the limitations) using an enumeration:

• ToNumberPolicy.DOUBLE that implements the default behavior of the Object type adapter returning Doubles only.
• ToNumberPolicy.LAZILY_PARSED_NUMBER that implements the default behavior of the Number type adapter.
• ToNumberPolicy.LONG_OR_DOUBLE that tries to parse a number as a Long, otherwise then tries to parse it as a Double, if the number cannot be parsed as a Long.
• ToNumberPolicy.BIG_DECIMAL that can parse numbers of arbitrary range and precision.

Call-site is expected to extract proper values using the methods declared in java.lang.Number.

Examples of use:

Default behavior, backwards-compatible with the previous versions of Gson

Gson gson = new GsonBuilder()
  .setObjectToNumberStrategy(ToNumberPolicy.DOUBLE) // explicit default, may be omitted
  .create();
List<Object> actual = gson.fromJson("[null, 10, 10.0]", new TypeToken<List<Object>>() {}.getType());
List<Double> expected = Arrays.asList(null, 10.0, 10.0);
assertEquals(expected, actual);

Gson gson = new GsonBuilder()
    .setNumberToNumberStrategy(ToNumberPolicy.LAZILY_PARSED_NUMBER) // explicit default, may be omitted
    .create();
List<Number> actual = gson.fromJson("[null, 10, 10.0]", new TypeToken<List<Number>>() {}.getType());
List<Object> expected = Arrays.<Object>asList(null, new LazilyParsedNumber("10"), new LazilyParsedNumber("10.0"));
assertEquals(expected, actual);

Object-declared numbers are always LazilyParsedNumbers

Gson gson = new GsonBuilder()
  .setObjectToNumberStrategy(ToNumberPolicy.LAZILY_PARSED_NUMBER)
  .create();
List<Object> actual = gson.fromJson("[null, 10, 10.0]", new TypeToken<List<Object>>() {}.getType());
List<LazilyParsedNumber> expected = Arrays.asList(null, new LazilyParsedNumber("10"), new LazilyParsedNumber("10.0"));
assertEquals(expected, actual);

Number-declared numbers are always Doubles

Gson gson = new GsonBuilder()
  .setNumberToNumberStrategy(ToNumberPolicy.DOUBLE)
  .create();
List<Number> actual = gson.fromJson("[null, 10, 10.0]", new TypeToken<List<Number>>() {}.getType());
List<Double> expected = Arrays.asList(null, 10.0, 10.0);
assertEquals(expected, actual);

Object-declared numbers are either Long or Double

Gson gson = new GsonBuilder()
  .setObjectToNumberStrategy(ToNumberPolicy.LONG_OR_DOUBLE)
  .create();
List<Object> actual = gson.fromJson("[null, 10, 10.0]", new TypeToken<List<Object>>() {}.getType());
List<? extends Number> expected = Arrays.asList(null, 10L, 10.0);
assertEquals(expected, actual);

Object-declared numbers are BigDecimals

Gson gson = new GsonBuilder()
  .setObjectToNumberStrategy(ToNumberPolicy.BIG_DECIMAL)
  .create();
List<Object> actual = gson.fromJson("[null, 3.141592653589793238462643383279, 1e400]", new TypeToken<List<Object>>() {}.getType());
List<BigDecimal> expected = Arrays.asList(null, new BigDecimal("3.141592653589793238462643383279"), new BigDecimal("1e400"));
assertEquals(expected, actual);

Custom bytes-only:

Gson gson = new GsonBuilder()
  .setObjectToNumberStrategy(new ToNumberStrategy() {
    @Override
    public Byte toNumber(final JsonReader in)
            throws IOException {
      return (byte) in.nextInt();
    }
  })
  .create();
List<Object> actual = gson.fromJson("[null, 10, 20, 30]", new TypeToken<List<Object>>() {}.getType());
List<Byte> expected = Arrays.asList(null, (byte) 10, (byte) 20, (byte) 30);
assertEquals(expected, actual);

Custom deserialization does not affect Byte-declared deserialization:

ToNumberStrategy fail = new ToNumberStrategy() {
    @Override
    public Byte toNumber(final JsonReader in) {
      throw new AssertionError();
    }
  };
Gson gson = new GsonBuilder()
  .setObjectToNumberStrategy(fail)
  .setNumberToNumberStrategy(fail)
  .create();
List<Object> actual = gson.fromJson("[null, 10, 20, 30]", new TypeToken<List<Byte>>() {}.getType());
List<Byte> expected = Arrays.asList(null, (byte) 10, (byte) 20, (byte) 30);
assertEquals(expected, actual);

Is there a reason why the deepCopy methods are not public? I see that they were public for some time in an earlier revision then was made "default" access level but I couldn't find the reason.

Hi, as the following error describes, java records (preview feature) deserialization isn't working in gson, Jackson is adding support in its very soon release 2.12, is there going to be same support/fix in gson ?

java.lang.AssertionError: AssertionError (GSON 2.8.6): java.lang.IllegalAccessException: Can not set final java.lang.String field JsonGsonRecordTest$Emp.name to java.lang.String

Here's a sample test

  record Emp(String name) {}

  @Test
  void deserializeEngineer() {
    Gson j = new GsonBuilder().setPrettyPrinting().create();
    var empJson = """
            {
              "name": "bob"
            }""";
    var empObj = j.fromJson(empJson, Emp.class);
  }

I have created a patch against gson-2.1 that adds code for allowing classes to 
define serialization and deserialization by implementing a simple interface. 
The benefit of this approach is that there is no longer a need to register 
special handlers for each class that requires custom serialization. It can be 
used as follows:

public class Foo implements JsonSerialization, 
JsonDeserializedBy<FooDeserializer> {
    public String name;
    public JsonElement serialize (JsonSerializationContext jsc) {
        return new JsonPrimitive(name);
    }
}

public class FooDeserializer implements JsonDeserializer<Foo> {
    public Foo deserialize(JsonElement je, Type type, JsonDeserializationContext jdc) {
        Foo f = new Foo();
        f.name = je.getAsString();
        return f;
    }
}

...
Foo foo = new Foo();
foo.name = "foo";
gson.toJson(foo); // "foo"
gson.fromJson(gson.toJson(foo), Foo.class).name; // "foo"

With my patch, a Gson object now checks the argument sent to toJson to 
determine if it implements JsonSerialization. If so, it calls its 
serialize(jsc) method to retrieve a JsonElement for that class.

When fromJson is called, the given class is inspected to determine if it 
implements the JsonDeserializer interface. If so, the class specified in the 
template parameter (in this case FooDeserializer) is used for deserialization 
by creating a new instance of that class (using the no-argument constructor), 
and then deserialize is called as with any JsonDeserializer object.

This patch adds the two new interfaces (JsonSerialization and 
JsonDeserialization) and adds a few lines of code to Gson in order to provide 
the aforementioned functionality. I'm not sure I chose the appropriate location 
to insert the functionality, and the code is pretty ugly, but it seems to work 
pretty well in my limited test cases.

I'll license the patch under the same license as gson, in case anyone is 
concerned about that.

Original issue reported on code.google.com by [email protected] on 12 Jan 2012 at 1:59

Attachments:

• gson-2.1-dynamic_serialization.patch

Long cannot be casted to Integer, Integer cannot be casted to Short, etc. Could you fix it in https://github.com/google/gson/blob/master/gson/src/main/java/com/google/gson/internal/bind/ObjectTypeAdapter.java? When serializing Map<String, Object> and deserializing, it throws Exception. I can't edit this, because I can't edit Spigot/Bukkit. If JSON save Integer, it should read Integer, not make Double unnecessarily.

I maked it in issue, because I had to download sources GSON and edit this:.

    case NUMBER:
      try {
        return in.nextInt();
      } catch(NumberFormatException exception) {
      }
      try {
        return in.nextLong();
      } catch(NumberFormatException exception) {
      }
      return in.nextDouble();

As noted in the documentation for JsonReader.setLenient, there are a number of areas where Gson accepts JSON inputs that are not strictly conformant, even when lenient mode is off:

• JsonReader allows the literals true, false and null to have any capitalization, for example fAlSe
• JsonReader supports the escape sequence \', representing a '
• JsonReader supports the escape sequence \LF (with LF being the Unicode character U+000A), resulting in a LF within the read JSON string
• JsonReader allows unescaped control characters (U+0000 through U+001F)

To which we could add that it allows a trailing comma in JSON objects, for example {"foo": "bar", "baz": "buh",} as noted in #494.

We could imagine that GsonBuilder would acquire a method setStrict(), mutually exclusive with setLenient() and that JsonReader would likewise acquire setStrict(boolean) and isStrict(). We can't make strict mode the default, for fear of breaking existing users, but we could recommend it.

We've been reluctant to make large-scale changes because they are likely to cause pain for people with unmerged PRs. But at this point I think there are relatively few open PRs that we are likely to merge, thanks largely to the heroic work of @Marcono1234. So this would be as good a time as any to consider at least:

• Port tests from JUnit 3 to JUnit 4. (Google's internal systems don't support JUnit 5 so we can't use that.)
• Use Truth for clearer assertions in tests.
• Apply various automated fixes suggested by Error Prone and the like.
• Reformat all source files with google-java-format. Possibly also install a check that ensures that future PRs are also correctly formatted.

Addresses https://github.com/google/gson/issues/776

I don't think that setFormattingStyles(String style) (as proposed) should affect the newline, that would be orthogonal.

That idea has no explanation, but I'm thinking that it would be something similar to the formatting styles in programming languages (where to break and how to indent, for example K&R vs Linux kernel vs BSD KNF, etc.) If that is the idea then the kind of newline to use is not related to the style.

The "dangling new line at the end of the JSON" would indeed be part of the style.

Problem solved by the feature

Similar to #1700 JsonDeserializationContext should have a deserialize overload with TypeToken parameter to provide type-safety, and the documentation should then recommend that overload.

Feature description

Since JsonDeserializationContext is an interface and might be implemented by users, the deserialize overload would have to be implemented as interface default method. Therefore this has to wait until Gson targets Java 8 or newer. The default method could then simply delegate to the other overload, though Gson's internal implementation could override it to directly call Gson.fromJson(..., TypeToken).