Reactor is key value database and is a great alternative to Shared Preferences.

allprojects {
  repositories {
      ...
      maven { url 'https://jitpack.io' }
    }
  }

dependencies {
    implementation 'com.github.aaaamirabbas:reactor:1.5.1'
}

val reactor = Reactor(context)
val reactor = Reactor(context, false) // disable encryption

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reactor.put("firstName", "abbas")
reactor.put("lastName", null)
reactor.put("age", 23)
reactor.put("customDataClass", SampleData())

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val firstName = reactor.get<String>("firstName")
val lastName : String? = reactor.get("lastName")
val isDay = reactor.get<Boolean>("isDay", false)
val customDataClass = reactor.get("customDataClass")

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reactor.remove<Int>("year", "week")
reactor.eraseAllData()

Reactor reactor = new Reactor(getContext());
Reactor reactor = new Reactor(getContext(), false); // disable encryption

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reactor.put("firstName", "abbas");
reactor.put("lastName", null);
reactor.put("age", 23);
reactor.put("customDataClass", new SampleData());

-----------------------------------------------------------

String firstName = reactor.get("firstName", "abbas");
String lastName = reactor.get("lastName", null);
Integer age = reactor.get("age", 26);
SampleData customDataClass = reactor.get("array");

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reactor.remove("age", 0);
reactor.eraseAllData();