Gson version

e2e851c

Java / Android version

openjdk version "11.0.13" 2021-10-19
OpenJDK Runtime Environment Temurin-11.0.13+8 (build 11.0.13+8)
OpenJDK 64-Bit Server VM Temurin-11.0.13+8 (build 11.0.13+8, mixed mode)

Description

EnumMap deserialization fails with ClassCastException:

java.lang.ClassCastException: class java.util.LinkedHashMap cannot be cast to class java.util.EnumMap

The underlying issue is related to #1708, it appears special handling for EnumMap is missing.
(I am a bit surprised that this issue has not been mentioned here anywhere before.)

Reproduction steps

Test case:

private static enum MyEnum {
  VALUE1, VALUE2
}

public void testEnumMap() throws Exception {
  EnumMap<MyEnum, String> map = new EnumMap<MyEnum, String>(MyEnum.class);
  map.put(MyEnum.VALUE1, "test");
  String json = gson.toJson(map);
  assertEquals("{\"VALUE1\":\"test\"}", json);

  Type type = new TypeToken<EnumMap<MyEnum, String>>() {}.getType();
  EnumMap<?, ?> actualMap = gson.fromJson("{\"VALUE1\":\"test\"}", type);
  Map<?, ?> expectedMap = Collections.singletonMap(MyEnum.VALUE1, "test");
  assertEquals(expectedMap, actualMap);
}

Exception stack trace

Not really useful because ClassCastException occurs in user code.