Android使用sharedpreference设置并获取数据给出错误

Question

我想使用共享首选项来持久化数据。但它给了我一个错误，

java.lang.IllegalStateException: Expected BEGIN_ARRAY but was BEGIN_OBJECT at line 1 column 2 path $

和

com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was BEGIN_OBJECT at line 1 column 2 path $

我没有得到什么问题。 我的代码在这里，

public void setStoreType(List<StoreType> st) {
    GsonBuilder gsonBuilder = new GsonBuilder();
    gsonBuilder.registerTypeAdapter(StoreType.class, new StoreType());

    Gson gson = gsonBuilder.create();
    JsonElement element = gson.toJsonTree(st, new TypeToken<List<StoreType>>() {
    }.getType());

    if (!element.isJsonObject()) {

    } else {
        pref = PreferenceManager
                .getDefaultSharedPreferences(getBaseContext());
        editor = pref.edit();
        editor.putString("STORE_TYPE", element.getAsJsonObject()
                .toString());
        editor.commit();
    }
}

public List<StoreType> getStoreType() {
    GsonBuilder gsonBuilder = new GsonBuilder();

    gsonBuilder.registerTypeAdapter(StoreType.class, new StoreType());

    Gson gson = new Gson();
    pref = PreferenceManager.getDefaultSharedPreferences(getBaseContext());
    Type type = new TypeToken<List<StoreType>>() {
    }.getType();

    if (gson.fromJson(pref.getString("STORE_TYPE", "{}"), type) == "{}") {
        return new ArrayList<StoreType>();
    }
    return gson.fromJson(pref.getString("STORE_TYPE", "{}"), type);

}

我想在其中设置arraylist。请告诉我这是什么问题。谢谢。