为什么Gson Preconditions会在这种情况下失败？

Question

我正在为该类编写一个反序列化器ForeignCollection,它是abstract在ORMLite Android库中提供给我的.请参阅下面的代码.

public class ForeignCollectionDeserializer implements JsonDeserializer<ForeignCollectionDeserializer> {
    @Override
    public ForeignCollection deserialize(JsonElement jsonElement, Type type, JsonDeserializationContext jsonDeserializationContext) throws JsonParseException {
        ...
    }
}

我也试过实现JsonDeserializer<?>和JsonDeserialzer(没有通用类型)

我正在使用GsonBuilder.registerTypeAdapter注册解串器.

GsonBuilder gb = new GsonBuilder();

gb.registerTypeAdapter(ForeignCollection.class, new ForeignCollectionDeserializer());
Gson gson = gb.create();

然而,registerTypeAdapter()抛出这个:

06-11 11:27:27.937: E/AndroidRuntime(15197): FATAL EXCEPTION: main
06-11 11:27:27.937: E/AndroidRuntime(15197): Process: com.myapp, PID: 15197
06-11 11:27:27.937: E/AndroidRuntime(15197): java.lang.IllegalArgumentException
06-11 11:27:27.937: E/AndroidRuntime(15197):    at com.google.gson.internal.$Gson$Preconditions.checkArgument($Gson$Preconditions.java:42)
06-11 11:27:27.937: E/AndroidRuntime(15197):    at com.google.gson.GsonBuilder.registerTypeAdapter(GsonBuilder.java:448)

我正在逐步完成代码,然后从GsonBuilder下面找到有问题的部分.

public GsonBuilder registerTypeAdapter(Type type, Object typeAdapter) {
    $Gson$Preconditions.checkArgument(typeAdapter instanceof JsonSerializer<?>
            || typeAdapter instanceof JsonDeserializer<?>
            || typeAdapter instanceof InstanceCreator<?>
            || typeAdapter instanceof TypeAdapter<?>);
    if (typeAdapter instanceof InstanceCreator<?>) {
        instanceCreators.put(type, (InstanceCreator) typeAdapter);
    }

我typeAdapter instanceof JsonDeserializer<?>在调试模式下进行了评估,发现它实际上是false

其实我已经评估了所有这些:

• typeAdapter instanceof JsonDeserializer
• typeAdapter instanceof JsonDeserializer<ForeignCollection>
• typeAdapter instanceof JsonDeserializer<?>

他们都是假的.

当我声明typeAdapter为一个实现Object的类型时ForeignCollectionsDeserializer,这是JsonDeserializer怎么回事？

Answer 1

事实证明我有多个不正确的导入.

我不小心导入了Gson的另一个库实现JsonDeserializer,导致代码编译,但instanceof条件不通.

SMH