Storing List in Shared Preference Android

In this article, we are going to learn how to store list in shared preference in Android. So let’s get started.

For storing list of object(String used in this article or any other object) into Shared preference, first we need to convert List<String> into string. And we easily convert list of object in Java or Kotlin into JSON string using Gson.

Gson is a Java library that can be used to convert Java Objects into their JSON representation. It can also be used to convert a JSON string to an equivalent Java object.

Before using Gson in our project, please add below dependency to your app level Gradle file.

Gradle:

dependencies {
  api 'com.google.code.gson:gson:2.9.0'
}

dependencies {

api 'com.google.code.gson:gson:2.9.0'

}

Converting List of object into JSON string:

List<String> data = new ArrayList<String>();
public static final String PREF = "PREF";
private static final String KEY = "KEY_DATA";

//adding values to list
data.add("Flutter"); 
data.add("Android");
data.add("iOS");

String convertedData = new Gson().toJson(data); // converted to string.

List<String> data = new ArrayList<String>();

public static final String PREF = "PREF";

private static final String KEY = "KEY_DATA";

//adding values to list

data.add("Flutter");

data.add("Android");

data.add("iOS");

String convertedData = new Gson().toJson(data); // converted to string.

Create your preference editor:

public static SharedPreferences.Editor getSharedPreferenceEditor(Context context, String preferenceFile) {
        return context.getSharedPreferences(preferenceFile, MODE_PRIVATE).edit();
    }

// put convertedData into shared preference
getSharedPreferenceEditor(context, PREF).putString(KEY, convertedData).apply();

public static SharedPreferences.Editor getSharedPreferenceEditor(Context context, String preferenceFile) {

return context.getSharedPreferences(preferenceFile, MODE_PRIVATE).edit();

}

// put convertedData into shared preference

getSharedPreferenceEditor(context, PREF).putString(KEY, convertedData).apply();

Shared preference to get data:

public static SharedPreferences getSharedPreference(Context context, String preferenceFile) {
        return context.getSharedPreferences(preferenceFile, MODE_PRIVATE);
    }

public static SharedPreferences getSharedPreference(Context context, String preferenceFile) {

return context.getSharedPreferences(preferenceFile, MODE_PRIVATE);

}

Accessing stored JSON string from shared preference as List of Object:

String retrievedDataString = getSharedPreference(context,           PREF).getString(KEY, null);

List<String> retrievedDataInList = 
        Type type = new TypeToken<List<String>>() {
        }.getType();
        return new Gson().fromJson(retrievedDataString, type);

String retrievedDataString = getSharedPreference(context, PREF).getString(KEY, null);

List<String> retrievedDataInList =

Type type = new TypeToken<List<String>>() {

}.getType();

return new Gson().fromJson(retrievedDataString, type);

Here, type is used to tell Gson that we want this JSON to be translated to a List of Strings.

Happy Coding 🙂

Ravi Kishor 31 March 2022

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Storing List in Shared Preference Android

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