How to implement Datastore in java based android app?

Question

I can only find ways to implement datastore through Kotlin. I have tried creating it with DataStore<Preferences> datastore = new Datastore<Preferences> but as soon as proceed with it, it overrides to methods namely save and loadData but the parameters passed in them are also in Kotlin. Should I proceed with Sharedpreferences only?

Please read [How to ask](https://stackoverflow.com/help/how-to-ask) and update your question with recommendations. — fartem, Feb 05 '21 at 16:58

score 5 · Accepted Answer · answered Feb 05 '21 at 17:46

There are few steps to implement dataStore in java base.

First and foremost, it is good to notice that there are 2 different types of dependencies for the datastore.

TYPED datastore
Preferences DataStore (SharedPreferences like APIs)

Here are some steps to implement the latter one in the java based application.

1. Implementation

// Preferences DataStore (SharedPreferences like APIs)
dependencies {
  implementation "androidx.datastore:datastore-preferences:1.0.0-alpha06"

  // RxJava3 support
  implementation "androidx.datastore:datastore-preferences-rxjava3:1.0.0-alpha06"
}

2. Create a Preferences DataStore

DataStore<Preferences> dataStore =
  new RxPreferenceDataStoreBuilder(context, /*name=*/ "settings").build();

3. Write to a Preferences DataStore

Single<Preferences> updateResult =  RxDataStore.updateDataAsync(dataStore, 
prefsIn -> {
  MutablePreferences mutablePreferences = prefsIn.toMutablePreferences();
  Integer currentInt = prefsIn.get(INTEGER_KEY);
  mutablePreferences.set(INTEGER_KEY, currentInt != null ? currentInt + 1 : 1);
  return Single.just(mutablePreferences);
});

// The update is completed once updateResult is completed.

3. Read from a Preferences DataStore

Preferences.Key<Integer> EXAMPLE_COUNTER = PreferencesKeys.int("example_counter");

Flowable<Integer> exampleCounterFlow =
  RxDataStore.data(dataStore).map(prefs -> prefs.get(EXAMPLE_COUNTER));

if you want to do more complex please checkout the full documentation

Does not explain how to set up a listener when Flowable is ready and the integer can finally be accessed. — Ezequiel Adrian, Apr 29 '23 at 21:36

maxvolk · Answer 2 · 2023-05-05T10:58:16.223

I am new to posting here, so I can not add a comment, but I want to build on the answer from Mehran. Also the answer is old, so I do not know if this worked like that, but I noticed several things:

Now, you dont have to implement the alpha versions:

//DataStore instead of SharedPreferences
implementation "androidx.datastore:datastore-preferences:1.0.0"
//RxJava2 support
implementation "androidx.datastore:datastore-preferences-rxjava2:1.0.0"

Furthermore, If you want to use the RxDataStore and the associated RxDataStoreBuilder the simple DataStore doesnt work:

RxDataStore<Preferences> dataStoreRX;
dataStoreRX = new RxPreferenceDataStoreBuilder(this,"datastorename").build();

To get data from the DataStore you can use:

value.blockingGet();

But there is way more to that. If you want to use the DataStore across several activities you need to use a Singleton. The reason is you cant create more than one instance of one DataStore. That is in the documentation but I think it is not complete. Also error-handling is not described there.

I elaborate more on this here: Link to Medium

A little shame with the plug, but one shall not start a question here if there is no actual question. So I hope this helps people who want to use it.

How to implement Datastore in java based android app?

2 Answers2