Best Android Data Passing and Routing Libraries in 2021

In any type of significant project, you will certainly need more than one page. These pages we represent them using Activity or Fragment in android. Routing in this context is the act of navigating from one page to another. The page may be either an activity or fragment.

Data passsing involves passing data from one page to another. That data may be simple primitive types like strings and integers or custom objects, like say a Student or Teacher. You typically use intent and bundles in android but their are libraries that make this process easier, more flexible and less error prone. In this piece we look at these.

(a). CachePot

CachePot is a simple open source for data cache management and passing data object between Fragments(Activities) without Pacelable and Serializable.

Questions CachePot helps answer.

Here is a summary of the problems cachepot helps you answer:

How to Pass Data Between Activities
How to Pass Data Between Fragments
How to pass multiple data types between activities/fragments.
How to Pass Data Between Activities and Fragments
How to Pass Data From PageAdapter to Fragments.

Difference to other similar Libraries

Its easy to use.
Complete, encompassing both fragments and activities.
Ability to pass single or multiple data or types. Easily pass custom objects or collections for example.
No annotations or extension of classes.

Step 1: Installation

Install cachepot using the following implementation statement:

implementation 'com.github.kimkevin:cachepot:1.2.0’

Usage

How to Use CachePot:

1. Single Type, Single Data

Push your data object to CachePot instance in your Activity or Fragment.

public void push(Object data)

KoreanFood foodItem = new KoreanFood(1, "Kimchi", "Traditional fermented Korean side dish made of vegetables")
CachePot.getInstance().push(foodItem);
// open your activity or fragment

Pop your data object from CachePot after view changes

public Object pop(Class classType)

public class MainFragment extends Fragment{
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        KoreanFood foodItem = CachePot.getInstance().pop(KoreanFood.class);
    }

In case of Collection or Map

Push

List<KoreanFood> foodItems = new ArrayList<>();
foodItems.add(new KoreanFood(1, "Kimchi", "Traditional fermented Korean side dish made of vegetables"));
foodItems.add(new KoreanFood(2, "Kkakdugi", "A variety of kimchi in Korean cuisine"));

CachePot.getInstance().push(foodItems);
// open your activity or fragment

Pop

List<KoreanFood> foodItems = CachePot.getInstance().pop(ArrayList.class);

2. Single Type, Multiple Data

How to pass Object(Model) Asynchronously when using ViewPager

First push your data object with position or id to CachePot instance in FragmentStatePagerAdapter(or FragmentPagerAdapter)

public void push(long id, Object data)

private class PagerAdapter extends FragmentStatePagerAdapter {
    ...
    public Fragment getItem(int position) {
        KoreanFood foodItem = foodItems.get(position);
        CachePot.getInstance().push(position, foodItem);
        // or
        CachePot.getInstance().push(foodItem.getId(), foodItem);
        ...
    }
}

public Object pop(long id)

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    ...
    if (getArguments() != null) {
        final int position = getArguments().getInt(ARG_POSITION);
        foodItem = CachePot.getInstance().pop(position);
        // or
        foodItem = CachePot.getInstance().pop(id);
    }
}

If more complecated views, use TAG

public void push(String tag, Object data) public void push(String tag, long id, Object data)

private class PagerAdapter extends FragmentStatePagerAdapter {
    ...
    public Fragment getItem(int position) {
        KoreanFood foodItem = foodItems.get(position);
        CachePot.getInstance().push(TAG, position, foodItem);
        // or
        CachePot.getInstance().push(TAG, foodItem.getId(), foodItem);
        ...
    }
}

public Object pop(String tag) public Object pop(String tag, long id)

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    ...
    if (getArguments() != null) {
        final int position = getArguments().getInt(ARG_POSITION);
        foodItem = CachePot.getInstance().pop(TAG, position);
        // or
        foodItem = CachePot.getInstance().pop(TAG, id);
    }
}

(b). RxRouter

A lightweight, simple, smart and powerful Android routing library.

Questions RxRouter helps solve

Here are the common problems RxRouter makes easier:

How to pass data between activities
Alternative to onActivityResult
How to route through classes as well as system and custom actions.

What makes RxRouter Unique

Here are the features that stand out in RxRouter:

Easy to use
Uses reactive programming
Provides routing via annotations
Pass multiple parameters between activities.
Can route through system and custom actions.
Firewall system - the ability to intercept a route.

Step 1: Installation

Install RxRouter:

dependencies {
    implementation 'zlc.season:rxrouter:x.y.z'
    annotationProcessor 'zlc.season:rxrouter-compiler:x.y.z'
}

For Kotlin you should use kapt instead of annotationProcessor.

Step 2: Usage

First add the @url annotation to the activity we need to route:

@Url("this is a url")
class UrlActivity : AppCompatActivity() {
    ...
}

Then create a class that is annotated with @Router to tell RxRouter that there is a router:

@Router
class MainRouter{
}

This class doesn't need to have any remaining code. RxRouter will automatically generate a RouterProvider based on the class name of the class. For example, MainRouter will generate MainRouterProvider.

Then we need to add these routers to RxRouterProviders:

class CustomApplication : Application() {
    override fun onCreate() {
        super.onCreate()
        RxRouterProviders.add(MainRouterProvider())
    }
}

Finally, we can start our performance:

RxRouter.of(context)
        .route("this is a uri")
        .subscribe()

You can have multiple parameters:

RxRouter.of(context)
        .with(10)                           //int value
        .with(true)                         //boolean value
        .with(20.12)                        //double value
        .with("this is a string value")     //string value
        .with(Bundle())                     //Bundle value
        .route("this is a uri")
        .subscribe()

You can use rxRouter to replace onActivityResult:

RxRouter.of(context)
        .with(false)
        .with(2000)
        .with(9999999999999999)
        .route("this is a uri")
        .subscribe {
            if (it.resultCode == Activity.RESULT_OK) {
                val intent = it.data
                val stringResult = intent.getStringExtra("result")
                result_text.text = stringResult
                stringResult.toast()
            }
        }