CODEWITHSUNDEEP
androidkotlinsharedpreferencesmoshi
MimiSoft
MimiSoft

Reputation: 51

Kotlin: How to save an arraylist in SharedPreferences

I created an android app with kotlin, in this app i use a WS that provides all the list of products. So, how can i save the list of products in SharedPreferences with a moshi library? Here's my code:

fun setArrayDataBykeyValue(context: Context, key: String, DataArrayList: Array<ProductData>) {
    val gson = Gson()
    val jsonString = gson.toJson(DataArrayList)
    val sp = context.getSharedPreferences(context.packageName, Context.MODE_PRIVATE)
    sp.edit().putString(key, jsonString).commit()
}

Upvotes: 2

Views: 3952

Answers (3)

goofy
goofy

Reputation: 444

I know you are asking for Moshi library, but I want provide you my Kotlin extension functions for working with ArrayList as saved in SharedPreferences using Gson.

I think it's easy to convert this to using Moshi library and it's very useful.

inline fun <reified T> SharedPreferences.addItemToList(spListKey: String, item: T) {
    val savedList = getList<T>(spListKey).toMutableList()
    savedList.add(item)
    val listJson = Gson().toJson(savedList)
    edit { putString(spListKey, listJson) }
}

inline fun <reified T> SharedPreferences.removeItemFromList(spListKey: String, item: T) {
    val savedList = getList<T>(spListKey).toMutableList()
    savedList.remove(item)
    val listJson = Gson().toJson(savedList)
    edit {
        putString(spListKey, listJson)
    }
}

fun <T> SharedPreferences.putList(spListKey: String, list: List<T>) {
    val listJson = Gson().toJson(list)
    edit {
        putString(spListKey, listJson)
    }
}

inline fun <reified T> SharedPreferences.getList(spListKey: String): List<T> {
    val listJson = getString(spListKey, "")
    if (!listJson.isNullOrBlank()) {
        val type = object : TypeToken<List<T>>() {}.type
        return Gson().fromJson(listJson, type)
    }
    return listOf()
}

Upvotes: 2

Amrit Bhattacharjee
Amrit Bhattacharjee

Reputation: 160

You can use GSON library for this.

At first, you have to convert the ArrayList to string. For example: 

val arrayString = Gson().toJson(arrayList)

Then, you can store the string in SharedPreference. To retrieve the String, you have to retrieve the String first and then convert it again to ArrayList. For example:

val collectionType = object : TypeToken<ArrayList<String>>() {}.type
arrayList = Gson().fromJson(arrayString, collectionType)

Let me know if you face any problem in this regard.

Upvotes: 0

vikas kumar
vikas kumar

Reputation: 11018

Here is how you can do it.

Moshi moshi = new Moshi.Builder().build();
Type type = Types.newParameterizedType(List.class, Person.class);
JsonAdapter< List > jsonAdapter = moshi.adapter(type);
String json = jsonAdapter.toJson(body.getParams());

where Person is your POJO or some model class.

and then save this string in shared preference and do the reverse like this to get back in List

List<Person> persons = jsonAdapter.fromJson(json);

Upvotes: 3

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