Android - SharedPreferences with serializable object

Question

I know that SharedPreferences has putString(), putFloat(), putLong(), putInt() and putBoolean(). But I need to store an object that is of type Serializable in SharedPreferences. How can I achieve this?

Answer 1

In short you cant, try serializing your object to a private file, it amounts to the same thing. sample class below:

import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.ObjectInputStream; import java.io.ObjectOutputStream;  import android.app.Activity; import android.content.Context;  /**  *  * Writes/reads an object to/from a private local file  *   *  */ public class LocalPersistence {       /**      *       * @param context      * @param object      * @param filename      */     public static void witeObjectToFile(Context context, Object object, String filename) {          ObjectOutputStream objectOut = null;         try {              FileOutputStream fileOut = context.openFileOutput(filename, Activity.MODE_PRIVATE);             objectOut = new ObjectOutputStream(fileOut);             objectOut.writeObject(object);             fileOut.getFD().sync();          } catch (IOException e) {             e.printStackTrace();         } finally {             if (objectOut != null) {                 try {                     objectOut.close();                 } catch (IOException e) {                     // do nowt                 }             }         }     }       /**      *       * @param context      * @param filename      * @return      */     public static Object readObjectFromFile(Context context, String filename) {          ObjectInputStream objectIn = null;         Object object = null;         try {              FileInputStream fileIn = context.getApplicationContext().openFileInput(filename);             objectIn = new ObjectInputStream(fileIn);             object = objectIn.readObject();          } catch (FileNotFoundException e) {             // Do nothing         } catch (IOException e) {             e.printStackTrace();         } catch (ClassNotFoundException e) {             e.printStackTrace();         } finally {             if (objectIn != null) {                 try {                     objectIn.close();                 } catch (IOException e) {                     // do nowt                 }             }         }          return object;     }  } 

Answer 2

The accepted answer is misleading, we can store serializable object into SharedPreferences by using GSON. Read more about it at google-gson.

you can add GSON dependency in Gradle file with:

compile 'com.google.code.gson:gson:2.7' 

Here the snippet:

First, create your usual sharedPreferences:

//Creating a shared preference SharedPreferences  mPrefs = getPreferences(MODE_PRIVATE); 

Saving from serializable object to preference:

 Editor prefsEditor = mPrefs.edit();  Gson gson = new Gson();  String json = gson.toJson(YourSerializableObject);  prefsEditor.putString("SerializableObject", json);  prefsEditor.commit(); 

Get serializable object from preference:

Gson gson = new Gson(); String json = mPrefs.getString("SerializableObject", ""); yourSerializableObject = gson.fromJson(json, YourSerializableObject.class);