AnnyPrefs

Android annotation based SharedPreferences wrapper with fluent interface.

Gradle Dependency

Due to annotation processing you will need some extra plugin, so in your main build.gradle file add the following classpath to your buildscript dependencies:

buildscript {
    ...
    dependencies {
        ...
        classpath 'com.neenbedankt.gradle.plugins:android-apt:1.8'
    }
}

Easily reference the library and annotation processor in your Android projects using this dependency in your module's build.gradle file:

dependencies {
	apt 'com.github.greenfrvr:annyprefs-compiler:1.0.0'
    compile 'com.github.greenfrvr:anny-prefs:1.0.0'
}

For JSON serialization [Google's GSON] (https://github.com/google/gson) library is currently used, so if you have no need to store non-primitive types you can exclude it like this:

dependencies {
	apt 'com.github.greenfrvr:annyprefs-compiler:1.0.0'
    compile ('com.github.greenfrvr:annyprefs:1.0.0') {
        exclude group: 'com.google.code.gson'
    }
}

Library available on both jCenter and Maven Central, but in case of any issues (library can't be resolved) use Bintray repo.

Add repository to your app's build.gradle file:

repositories {
    maven {
        url 'https://dl.bintray.com/greenfrvr/maven/'
    }
}

This will reference Bintray's Maven repository that contains hashtags widget directly, rather than going through jCenter first.

How to use

First of all we need to declare what kind of data we want to persist, i.e. to define properties which will be stored in SharedPreferences. For example:

@AnnyPref(name = "user")
public interface User {
    @StringPref(key = "user_name", value = "Arty")
    void username(String username);
    
    @IntPref(keyRes = R.string.user_age)
    void age(int username);
    
    @BoolPref(value = true)
    void firstLaunch(boolean isFirst);
    
    @DatePref
    void birthday(Date birthday);
    
    @ObjectPref(key = "user_address", type = Address.class)
    void address(Address address)
}

@AnnyPref annotation contains name field which defines whether to store these preferences in separate file or in default shared preferences file (default behavior). For current example (package)_anny_user.xml file will be created where prefs will be stored in, while default prefs stored in (package)_preferences.xml This annotation can be used only with interfaces.

@StringPref annotation defines stored property, i.e. it defines type (String), key and default value of stored property. There are two params key and value, which are both optional. All properties types are listed below.

key parameter defines the key of property which will be stored in shared preferences, if not defined method name will be used instead.

keyRes parameter defines string resource which will be used as key of property. It has higher priority than key, i.e. if both parameters are defined keyRes will be used.

value parameter defines default value which will be returned in case if the property have never been persisted before, there are predefined default values for each type of stored properties (String, Integer, Float etc.).

After declaring properties you have to rebuild the project (due to annotation processor need to generate some boilerplate) and you will get the following:

  UserPrefs prefs = AnnyPrefs.user(Context);
  
  SaveUser saveUser = prefs.save();
  RestoreUser restoreUser = prefs.restore();
  RemoveUser removeUser = prefs.remove();
  
  saveUser.username("greenfrvr").async();
  restoreUser.username();
  boolean isRemoved = removeUser.username().sync();

There are several generated classes which are based on declared interface. First of all main class which let you doing things with shared prefs is obtained by adding Prefs to declared interface name. In our case it is UserPrefs. The only way to get an instance of it is to call AnnyPrefs method corresponding to that prefs type. That method name is an interface name in lowercase. So when we call AnnyPrefs.user(Context) we will get UserPrefs instance which can return 3 base interfaces, that are SaveUser, RestoreUser and RemoveUser. These interfaces are returned by calling corresponding methods save(), restore() and remove(). Each of these interfaces let you work with stored properties with named methods (the methods names are exactly the same that declared in your interface with @AnnyPref annotation).

##Supported property types All types which are supported by SharedPreferences are obviously can be stored (String, Int, Float, Long, Boolean, StringSet). Also you can store java.util.Date properties and in fact any POJO which can be serialized to JSON by [Google's GSON] (https://github.com/google/gson) library.

Below is a list of all available annotations:

• @BooleanPref predefined value is false
• @IntPref predefined value is 0
• @FloatPref predefined value is 0.0f
• @LongPref predefined value is 0L
• @StringPref predefined value is ""
• @StringSetPref predefined value is null
• @DatePref predefined value is Date object with 0 milliseconds
• @ObjectPref predefined value is null. Instead of value property it has type property which defines class representing this property (which is required for serialization/deserialization).

There are no requirements about how annotated methods should look like, so you can define it in a way which let you use it later.

##Saving preferences Just like in SharedPreferences there are 2 ways to modify preferences by commiting (by calling sync()) and applying ( by calling async()) changes. For example:

  SaveUser saveUser = prefs.save();
  saveUser.username("greenfrvr");
  saveUser.age(23);
  saveUser.firstLaunch(false);
  
  boolean isPersisted = saveUser.sync(); //or you can call async() instead

Fluent inteface lets you saving multiple properties just with simple calls chain.

  AnnyPrefs.user(Context)
  	.save()
  	.username("greenfrvr").age(23).firstLaunch(false)
  	.async();

##Retreiving preferences Retreiving properties is very simple.

  RestoreUser restoreUser = prefs.restore();

  String name = restoreUser.username();
  int age = restoreUser.age();
  boolean isFirstLaunch = restoreUser.firstLaunch();

or if you need only one property

  AnnyPrefs.user(Context).restore().firstLaunch();

##Removing preferences Removing property values require to call sync() or async() to apply changes just like in saving preferences.

  boolean isRemoved = AnnyPrefs.user(Context).remove().username().age().async();

To clear all preferences just call clear() method.

  AnnyPrefs.user(Context).clear();

##Preferences listeners To track all preferences changes you can add SharedPreferences.OnSharedPreferenceChangeListener.

  AnnyPrefs.user(Context).registerListener(SharedPreferences.OnSharedPreferenceChangeListener)

To stop tracking unregister that listener by calling

  AnnyPrefs.user(Context).unregisterListener(SharedPreferences.OnSharedPreferenceChangeListener)

##Some tips When declaring preferences your interface's methods may look just as you want, but don't forget about Restore(interface name) interface which will be generated. For example you declared:

@AnnyPref
public interface User {
	@StringPref
	void username(String name);
}

RestoreUser interface will be generated for that case and it will be "mirroring" for declared one.

//Generated code, shouldn't be edited
public interface RestoreUser {
	String username();
}

Both User and RestoreUser interfaces can be used just as normal interfaces.

If you need some more information about how generated classes are designed you can browse them inside your project build/generated/source/apt directory.

License

 Copyright 2015 greenfrvr

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.