How to save List<Object> to SharedPreferences?

It only possible to use primitive types because preference keep in memory. But what you can use is serialize your types with Gson into json and put string into preferences:

private static SharedPreferences sharedPreferences = context.getSharedPreferences(STORE_FILE_NAME, Context.MODE_PRIVATE);

private static SharedPreferences.Editor editor = sharedPreferences.edit();

public <T> void setList(String key, List<T> list) {
    Gson gson = new Gson();
    String json = gson.toJson(list);

    set(key, json);
}

public static void set(String key, String value) {
    editor.putString(key, value);
    editor.commit();
}

Extra Shot from below comment by @StevenTB

To Retrive

 publicList<YourModel> getList(){
    List<YourModel> arrayItems;
    String serializedObject = sharedPreferences.getString(KEY_PREFS, null); 
    if (serializedObject != null) {
         Gson gson = new Gson();
         Type type = new TypeToken<List<YourModel>>(){}.getType();
         arrayItems = gson.fromJson(serializedObject, type);
     }
}

You can use GSON to convert Object -> JSON(.toJSON) and JSON -> Object(.fromJSON).

• Define your Tags with you want (for example):

  private static final String PREFS_TAG = "SharedPrefs";
  private static final String PRODUCT_TAG = "MyProduct";
  

• Get your sharedPreference to these tag's

  private List<Product> getDataFromSharedPreferences(){
      Gson gson = new Gson();
      List<Product> productFromShared = new ArrayList<>();
      SharedPreferences sharedPref = getApplicationContext().getSharedPreferences(PREFS_TAG, Context.MODE_PRIVATE);
      String jsonPreferences = sharedPref.getString(PRODUCT_TAG, "");    
  
      Type type = new TypeToken<List<Product>>() {}.getType();
      productFromShared = gson.fromJson(jsonPreferences, type);
  
      return preferences;
  }
  

• Set your sharedPreferences

  private void setDataFromSharedPreferences(Product curProduct){
      Gson gson = new Gson();
      String jsonCurProduct = gson.toJson(curProduct);
  
      SharedPreferences sharedPref = getApplicationContext().getSharedPreferences(PREFS_TAG, Context.MODE_PRIVATE);
      SharedPreferences.Editor editor = sharedPref.edit();
  
      editor.putString(PRODUCT_TAG, jsonCurProduct);
      editor.commit();
  }
  

• If you want to save an array of Products, do this:

  private void addInJSONArray(Product productToAdd){
  
      Gson gson = new Gson();
      SharedPreferences sharedPref = getApplicationContext().getSharedPreferences(PREFS_TAG, Context.MODE_PRIVATE);
  
      String jsonSaved = sharedPref.getString(PRODUCT_TAG, "");
      String jsonNewproductToAdd = gson.toJson(productToAdd);
  
      JSONArray jsonArrayProduct= new JSONArray();
  
      try {
          if(jsonSaved.length()!=0){
              jsonArrayProduct = new JSONArray(jsonSaved);
          }
          jsonArrayProduct.put(new JSONObject(jsonNewproductToAdd));
      } catch (JSONException e) {
          e.printStackTrace();
      }
  
      //SAVE NEW ARRAY
      SharedPreferences.Editor editor = sharedPref.edit();
      editor.putString(PRODUCT_TAG, jsonArrayProduct);
      editor.commit();
  }
  

SharedPreferences mPrefs = getPreferences(MODE_PRIVATE);

For save

Editor prefsEditor = mPrefs.edit();
Gson gson = new Gson();
String json = gson.toJson(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);