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https://github.com/evernote/android-state

A utility library for Android to save objects in a Bundle without any boilerplate.
https://github.com/evernote/android-state

android android-application annotation-processor boilerplate icepick kotlin kotlin-android

Last synced: 1 day ago
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A utility library for Android to save objects in a Bundle without any boilerplate.

Host: GitHub
URL: https://github.com/evernote/android-state
Owner: Evernote
License: epl-1.0
Created: 2017-01-17T20:45:28.000Z (almost 8 years ago)
Default Branch: master
Last Pushed: 2019-09-29T22:09:34.000Z (about 5 years ago)
Last Synced: 2024-12-15T19:08:57.271Z (9 days ago)
Topics: android, android-application, annotation-processor, boilerplate, icepick, kotlin, kotlin-android
Language: Java
Homepage:
Size: 538 KB
Stars: 859
Watchers: 33
Forks: 49
Open Issues: 1
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE

Awesome Lists containing this project

README

        # DEPRECATED

This library is not maintained anymore.

# ~~Android-State~~

A utility library for Android to save objects in a `Bundle` without any boilerplate. It uses an annotation processor to wire up all dependencies.

## Download

Download the latest [library](https://search.maven.org/#search%7Cga%7C1%7Ca%3A%22android-state%22) and [processor](https://search.maven.org/#search%7Cga%7C1%7Ca%3A%22android-state-processor%22) or grab via Gradle:

```groovy

dependencies {

    implementation 'com.evernote:android-state:1.4.1'

    // Java only project

    annotationProcessor 'com.evernote:android-state-processor:1.4.1'

    // Kotlin with or without Java

    kapt 'com.evernote:android-state-processor:1.4.1'

}

```

You can read the [JavaDoc here](https://evernote.github.io/android-state/javadoc/).

## Usage

It's recommended to turn on a global setting in your `Application` class to save and restore the instance state of all activities and fragments from the support library. After that you only need to annotate your fields with `@State` inside of your fragments and activities. You can save any type which can be saved in a `Bundle` like the `String`, `Serializable`, and `Parcelable` data structures.

```java

public class App extends Application {

    @Override

    public void onCreate() {

        super.onCreate();

        StateSaver.setEnabledForAllActivitiesAndSupportFragments(this, true);

    }

}

public class MainActivity extends Activity {

    @State

    public int mValue;

    // ...

}

class MainFragment : Fragment() {

    @State

    var title = "My fragment"

}

```

If you want to save the state of any other object or didn't turn on the global setting, then you need to use the `StateSaver` class for manually saving and restoring the instance state.

```java

public class MainActivity extends Activity {

    @State

    public int mValue;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        StateSaver.restoreInstanceState(this, savedInstanceState);

    }

    @Override

    protected void onSaveInstanceState(Bundle outState) {

        super.onSaveInstanceState(outState);

        StateSaver.saveInstanceState(this, outState);

    }

}

```

## Advanced

You can also save state in a `View` class.

```java

public class TestView extends View {

    @State

    public int mState;

    public TestView(Context context) {

        super(context);

    }

    @Override

    protected Parcelable onSaveInstanceState() {

        return StateSaver.saveInstanceState(this, super.onSaveInstanceState());

    }

    @Override

    protected void onRestoreInstanceState(Parcelable state) {

        super.onRestoreInstanceState(StateSaver.restoreInstanceState(this, state));

    }

}

```

It is recommended that saved properties not be `private`. If a property is `private`, then a non-private getter and setter method are required. This is especially useful for Kotlin, because properties are `private` by default and the aforementioned methods are generated by the compiler.

If you **want** your getter and setter to be used rather than the field value being used directly, the field **must** be private.

```kotlin

class DemoPresenter : Presenter() {

    @State

    var counter = 0

    // ...

}

```

Of course, this also works in Java.

```java

public class TitleUpdater {

    @State

    private String mTitle;

    public String getTitle() {

        return mTitle;

    }

    public void setTitle(String title) {

        mTitle = title;

    }

}

```

If you have a private field and don't want to provide a getter or setter method, then you can fallback to reflection. However, this method is not recommended.

```java

public class ImageProcessor {

    @StateReflection

    private byte[] mImageData;

    // ...

}

```

A custom bundler can be useful, if a class doesn't implement the `Parcelable` or `Serializable` interface, which oftentimes happens with third party dependencies.

```java

public class MappingProvider {

    @State(PairBundler.class)

    public Pair mMapping;

    public static final class PairBundler implements Bundler> {

        @Override

        public void put(@NonNull String key, @NonNull Pair value, @NonNull Bundle bundle) {

            bundle.putString(key + "first", value.first);

            bundle.putInt(key + "second", value.second);

        }

        @Nullable

        @Override

        public Pair get(@NonNull String key, @NonNull Bundle bundle) {

            if (bundle.containsKey(key + "first")) {

                return new Pair<>(bundle.getString(key + "first"), bundle.getInt(key + "second"));

            } else {

                return null;

            }

        }

    }

}

```

### Lint

The library comes with Lint rules to verify a correct usage of the library. The lint checks work in Java and Kotlin files.

### ProGuard

This library comes with a ProGuard config. No further steps are required, but all necessary rules can be found [here](library/proguard.cfg).

## [Icepick](https://github.com/frankiesardo/icepick)

This library is based on [Icepick](https://github.com/frankiesardo/icepick), a great library from Frankie Sardo. However, Icepick is missing some features important to us: it [doesn't support properties](https://github.com/frankiesardo/icepick/issues/81) which is a [bummer for Kotlin](https://github.com/frankiesardo/icepick/issues/47). Also, Icepick does not support private fields which may break encapsulation. A tool shouldn't force you into this direction.

Since Icepick is implemented in Clojure, we decided that it's better for us to rewrite the annotation processor in Java. Unfortunately, that makes it hard to push our features into Icepick itself. That's why we decided to fork the project.

There are also alternatives for Kotlin like [IceKick](https://github.com/tinsukE/icekick). We did not want to use two libraries to solve the same problem for two different languages; we wanted to have one solution for all scenarios.

Upgrading to this library from Icepick is easy. The API is the same; only the packages and the class name (i.e. from `Icepick` to `StateSaver`) have changed. If Icepick works well for you, then there's no need to upgrade.

## License

```

Copyright (c) 2017 Evernote Corporation.

All rights reserved. This program and the accompanying materials

are made available under the terms of the Eclipse Public License v1.0

which accompanies this distribution, and is available at

http://www.eclipse.org/legal/epl-v10.html

Files produced by Android-State code generator are not subject to terms

of the Eclipse Public License 1.0 and can be used as set out in the

copyright notice included in the generated files.

```