store and retrieve a class object in shared preference
AndroidObjectSharedpreferencesAndroid Problem Overview
In Android can we store an object of a class in shared preference and retrieve the object later?
If it is possible how to do it? If it is not possible what are the other possibilities of doing it?
I know that serialization is one option, but I am looking for possibilities using shared preference.
Android Solutions
Solution 1 - Android
Yes we can do this using Gson
Download Working code from GitHub
SharedPreferences mPrefs = getPreferences(MODE_PRIVATE);
For save
Editor prefsEditor = mPrefs.edit();
Gson gson = new Gson();
String json = gson.toJson(myObject); // myObject - instance of MyObject
prefsEditor.putString("MyObject", json);
prefsEditor.commit();
For get
Gson gson = new Gson();
String json = mPrefs.getString("MyObject", "");
MyObject obj = gson.fromJson(json, MyObject.class);
##Update1
The latest version of GSON can be downloaded from github.com/google/gson.
##Update2
If you are using Gradle/Android Studio just put following in build.gradle
dependencies section -
implementation 'com.google.code.gson:gson:2.6.2'
Solution 2 - Android
we can use Outputstream to output our Object to internal memory. And convert to string then save in preference. For example:
mPrefs = getPreferences(MODE_PRIVATE);
SharedPreferences.Editor ed = mPrefs.edit();
ByteArrayOutputStream arrayOutputStream = new ByteArrayOutputStream();
ObjectOutputStream objectOutput;
try {
objectOutput = new ObjectOutputStream(arrayOutputStream);
objectOutput.writeObject(object);
byte[] data = arrayOutputStream.toByteArray();
objectOutput.close();
arrayOutputStream.close();
ByteArrayOutputStream out = new ByteArrayOutputStream();
Base64OutputStream b64 = new Base64OutputStream(out, Base64.DEFAULT);
b64.write(data);
b64.close();
out.close();
ed.putString(key, new String(out.toByteArray()));
ed.commit();
} catch (IOException e) {
e.printStackTrace();
}
when we need to extract Object from Preference. Use the code as below
byte[] bytes = mPrefs.getString(indexName, "{}").getBytes();
if (bytes.length == 0) {
return null;
}
ByteArrayInputStream byteArray = new ByteArrayInputStream(bytes);
Base64InputStream base64InputStream = new Base64InputStream(byteArray, Base64.DEFAULT);
ObjectInputStream in;
in = new ObjectInputStream(base64InputStream);
MyObject myObject = (MyObject) in.readObject();
Solution 3 - Android
Not possible.
You can only store, simple values in SharedPrefences SharePreferences.Editor
What particularly about the class do you need to save?
Solution 4 - Android
I had the same problem, here's my solution:
I have class MyClass
and ArrayList<MyClass>
that I want to save to Shared Preferences. At first I've added a method to MyClass
that converts it to JSON object:
public JSONObject getJSONObject() {
JSONObject obj = new JSONObject();
try {
obj.put("id", this.id);
obj.put("name", this.name);
} catch (JSONException e) {
e.printStackTrace();
}
return obj;
}
Then here's the method for saving object ArrayList<MyClass> items
:
SharedPreferences mPrefs = context.getSharedPreferences("some_name", 0);
SharedPreferences.Editor editor = mPrefs.edit();
Set<String> set= new HashSet<String>();
for (int i = 0; i < items.size(); i++) {
set.add(items.get(i).getJSONObject().toString());
}
editor.putStringSet("some_name", set);
editor.commit();
And here's the method for retrieving the object:
public static ArrayList<MyClass> loadFromStorage() {
SharedPreferences mPrefs = context.getSharedPreferences("some_name", 0);
ArrayList<MyClass> items = new ArrayList<MyClass>();
Set<String> set = mPrefs.getStringSet("some_name", null);
if (set != null) {
for (String s : set) {
try {
JSONObject jsonObject = new JSONObject(s);
Long id = jsonObject.getLong("id"));
String name = jsonObject.getString("name");
MyClass myclass = new MyClass(id, name);
items.add(myclass);
} catch (JSONException e) {
e.printStackTrace();
}
}
return items;
}
Note that StringSet
in Shared Preferences is available since API 11.
Solution 5 - Android
Using Gson Library:
dependencies {
compile 'com.google.code.gson:gson:2.8.2'
}
Store:
Gson gson = new Gson();
//Your json response object value store in json object
JSONObject jsonObject = response.getJSONObject();
//Convert json object to string
String json = gson.toJson(jsonObject);
//Store in the sharedpreference
getPrefs().setUserJson(json);
Retrieve:
String json = getPrefs().getUserJson();
Solution 6 - Android
Using this object --> TinyDB--Android-Shared-Preferences-Turbo its very simple. you can save most of the commonly used objects with it like arrays, integer, strings lists etc
Solution 7 - Android
You can use Complex Preferences Android - by Felipe Silvestre library to store your custom objects. Basically, it's using GSON mechanism to store objects.
To save object into prefs:
User user = new User();
user.setName("Felipe");
user.setAge(22);
user.setActive(true);
ComplexPreferences complexPreferences = ComplexPreferences.getComplexPreferences(
this, "mypref", MODE_PRIVATE);
complexPreferences.putObject("user", user);
complexPreferences.commit();
And to retrieve it back:
ComplexPreferences complexPreferences = ComplexPreferences.getComplexPreferences(this, "mypref", MODE_PRIVATE);
User user = complexPreferences.getObject("user", User.class);
Solution 8 - Android
You could use GSON, using Gradle Build.gradle :
implementation 'com.google.code.gson:gson:2.8.0'
Then in your code, for example pairs of string/boolean with Kotlin :
val nestedData = HashMap<String,Boolean>()
for (i in 0..29) {
nestedData.put(i.toString(), true)
}
val gson = Gson()
val jsonFromMap = gson.toJson(nestedData)
Adding to SharedPrefs :
val sharedPrefEditor = context.getSharedPreferences(_prefName, Context.MODE_PRIVATE).edit()
sharedPrefEditor.putString("sig_types", jsonFromMap)
sharedPrefEditor.apply()
Now to retrieve data :
val gson = Gson()
val sharedPref: SharedPreferences = context.getSharedPreferences(_prefName, Context.MODE_PRIVATE)
val json = sharedPref.getString("sig_types", "false")
val type = object : TypeToken<Map<String, Boolean>>() {}.type
val map = gson.fromJson(json, type) as LinkedTreeMap<String,Boolean>
for (key in map.keys) {
Log.i("myvalues", key.toString() + map.get(key).toString())
}
Solution 9 - Android
Common shared preference (CURD) SharedPreference: to Store data in the form of value-key pairs with a simple Kotlin class.
var sp = SharedPreference(this);
Storing Data:
To store String, Int and Boolean data we have three methods with the same name and different parameters (Method overloading).
save("key-name1","string value")
save("key-name2",int value)
save("key-name3",boolean)
Retrieve Data: To Retrieve the data stored in SharedPreferences use the following methods.
sp.getValueString("user_name")
sp.getValueInt("user_id")
sp.getValueBoolean("user_session",true)
Clear All Data: To clear the entire SharedPreferences use the below code.
sp.clearSharedPreference()
Remove Specific Data:
sp.removeValue("user_name")
Common Shared Preference Class
import android.content.Context
import android.content.SharedPreferences
class SharedPreference(private val context: Context) {
private val PREFS_NAME = "coredata"
private val sharedPref: SharedPreferences = context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE)
//********************************************************************************************** save all
//To Store String data
fun save(KEY_NAME: String, text: String) {
val editor: SharedPreferences.Editor = sharedPref.edit()
editor.putString(KEY_NAME, text)
editor.apply()
}
//..............................................................................................
//To Store Int data
fun save(KEY_NAME: String, value: Int) {
val editor: SharedPreferences.Editor = sharedPref.edit()
editor.putInt(KEY_NAME, value)
editor.apply()
}
//..............................................................................................
//To Store Boolean data
fun save(KEY_NAME: String, status: Boolean) {
val editor: SharedPreferences.Editor = sharedPref.edit()
editor.putBoolean(KEY_NAME, status)
editor.apply()
}
//********************************************************************************************** retrieve selected
//To Retrieve String
fun getValueString(KEY_NAME: String): String? {
return sharedPref.getString(KEY_NAME, "")
}
//..............................................................................................
//To Retrieve Int
fun getValueInt(KEY_NAME: String): Int {
return sharedPref.getInt(KEY_NAME, 0)
}
//..............................................................................................
// To Retrieve Boolean
fun getValueBoolean(KEY_NAME: String, defaultValue: Boolean): Boolean {
return sharedPref.getBoolean(KEY_NAME, defaultValue)
}
//********************************************************************************************** delete all
// To clear all data
fun clearSharedPreference() {
val editor: SharedPreferences.Editor = sharedPref.edit()
editor.clear()
editor.apply()
}
//********************************************************************************************** delete selected
// To remove a specific data
fun removeValue(KEY_NAME: String) {
val editor: SharedPreferences.Editor = sharedPref.edit()
editor.remove(KEY_NAME)
editor.apply()
}
}
Blog: https://androidkeynotes.blogspot.com/2020/02/shared-preference.html
Solution 10 - Android
There is no way to store objects in SharedPreferences, What i did is to create a public class, put all the parameters i need and create setters and getters, i was able to access my objects,
Solution 11 - Android
Do you need to retrieve the object even after the application shutting donw or just during it's running ?
You can store it into a database.
Or Simply create a custom Application class.
public class MyApplication extends Application {
private static Object mMyObject;
// static getter & setter
...
}
<manifest xmlns:android="http://schemas.android.com/apk/res/android">
<application ... android:name=".MyApplication">
<activity ... />
...
</application>
...
</manifest>
And then from every activities do :
((MyApplication) getApplication).getMyObject();
Not really the best way but it works.
Solution 12 - Android
Yes .You can store and retrive the object using Sharedpreference