Verbose exception messages from gson?

Question

I'm trying to parse a big chunk of JSON with gson (assisted by GsonFire). Somewhere along the way it's throwing a JsonSyntaxException.

I know what the exception means, but I'm parsing a huge file and it would really help if I could figure out which token is causing the exception. Is there a way to get more verbose output from gson?

Exception is below:

com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:200)
    at com.google.gson.TypeAdapter.fromJsonTree(TypeAdapter.java:281)
    at io.gsonfire.gson.FireTypeAdapter.deserialize(FireTypeAdapter.java:93)
    at io.gsonfire.gson.FireTypeAdapter.read(FireTypeAdapter.java:52)
    at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.read(TypeAdapterRuntimeTypeWrapper.java:40)
    at com.google.gson.internal.bind.MapTypeAdapterFactory$Adapter.read(MapTypeAdapterFactory.java:186)
    at com.google.gson.internal.bind.MapTypeAdapterFactory$Adapter.read(MapTypeAdapterFactory.java:145)
    at com.google.gson.TypeAdapter.fromJsonTree(TypeAdapter.java:281)
    at io.gsonfire.gson.FireTypeAdapter.deserialize(FireTypeAdapter.java:93)
    at io.gsonfire.gson.FireTypeAdapter.read(FireTypeAdapter.java:52)
    at com.google.gson.TypeAdapter.fromJsonTree(TypeAdapter.java:281)
    at io.gsonfire.gson.FireTypeAdapter.deserialize(FireTypeAdapter.java:93)
    at io.gsonfire.gson.FireTypeAdapter.read(FireTypeAdapter.java:52)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:103)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:196)
    at com.google.gson.TypeAdapter.fromJsonTree(TypeAdapter.java:281)
    at io.gsonfire.gson.FireTypeAdapter.deserialize(FireTypeAdapter.java:93)
    at io.gsonfire.gson.FireTypeAdapter.read(FireTypeAdapter.java:52)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:103)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:196)
    at com.google.gson.TypeAdapter.fromJsonTree(TypeAdapter.java:281)
    at io.gsonfire.gson.FireTypeAdapter.deserialize(FireTypeAdapter.java:93)
    at io.gsonfire.gson.FireTypeAdapter.read(FireTypeAdapter.java:52)
    at com.google.gson.Gson.fromJson(Gson.java:810)
    at com.google.gson.Gson.fromJson(Gson.java:775)
    at com.google.gson.Gson.fromJson(Gson.java:724)
    at com.google.gson.Gson.fromJson(Gson.java:696)
    at com.inin.util.BinarySerializable.fromJsonFile(BinarySerializable.java:90)
    at com.inin.util.BinarySerializable.fromJsonFile(BinarySerializable.java:83)
    at com.inin.simulation.App.main(App.java:35)
Caused by: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING
    at com.google.gson.internal.bind.JsonTreeReader.expect(JsonTreeReader.java:139)
    at com.google.gson.internal.bind.JsonTreeReader.beginObject(JsonTreeReader.java:70)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:189)
    ... 29 more

Answer 1

With Gson 2.3, you get a much nicer exception. It tells you the JSONPath to the failure, for example:

com.google.gson.JsonSyntaxException: Expected a boolean but was NUMBER at line 1 column 4728 path $.history[0].change_status.deletions  
  at com.google.gson.stream.JsonReader.nextBoolean()
  at com.google.gson.TypeAdapters$3.read()
  at com.google.gson.TypeAdapters$3.read()
  at com.google.gson.ReflectiveTypeAdapter$1.read()
  at com.google.gson.ReflectiveTypeAdapter$Adapter.read()
  at com.google.gson.ReflectiveTypeAdapter$Adapter.read()
  at com.google.gson.ReflectiveTypeAdapter$1.read()
  at com.google.gson.ReflectiveTypeAdapter$Adapter.read()
  ...