Thursday, 19 July 2018

Launching Fragment B from Activity based on data collected from Fragment A with less boilerplate code

I have the following setup:

  1. I have an Activity that launches a FragmentA.
    FragmentA contains a recyclerView and an adapter.

  2. I have an interfaceA in the adapter which is implemented in FragmentA so that I get notified which position was clicked.

  3. I have a second interfaceB that I created in the FragmentA, which is implemented in the Activity that launched FragmentA in step 1.
  4. Finally, I'm launching FragmentB from the Activity based on data I get from interfaceB.

Everything is working fine, however the flow is tedious, and demands a lot of boilerplate code.

THE GOAL is to have the activity launch fragmentB that contains data from a single clicked item from the recyclerView within FragmentA.

Question: Can it be achieved differently?

Code Below:

Activity launches FragmentA:

Fragment fragment = fragmentManager.findFragmentByTag(FragmentA.class.getName());
    if (fragment == null) {

        fragment = Fragment.instantiate(this, FragmentA.class.getName());
    }
    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
    fragmentTransaction
            .replace(R.id.fragmentLayout, fragment, FragmentA.class.getName())
            .addToBackStack(FragmentA.class.getName())
            .commit();

Inside FragmentA we have recyclerView, and interfaceA implemented in the adapter:

Adapter Class:

        public class AdapterA extends RecyclerView.Adapter< AdapterA.ViewHolderA> {

        //instances
        private Context context;
        private List<Data> dataList;
        private OnItemClickListener onItemListClickListener;

        //Constructor
        public AdapterA (Context context, List<Data> dataList, OnItemClickListener onItemListClickListener {
        this.context = context;
        this.dataList = dataList;
        this.onItemListClickListener = onItemListClickListener;
    }

onCreateViewHolder....
onBindViewHolder....
getItemCount...

class ViewHolderA RecyclerView.ViewHolder {
//instances..
//Constructor...

}
        }

interface class interfaceA:

public interface OnItemClickListener {
    void onItemClick(View view, int position);
}

interface class interfaceB:

public interface SingleItemEventListener {
    void onSingleItemClicked(int position);
}

FragmentA class:

//Instances
private AdapterA adapter;
private RecyclerView recyclerView;
private onSingleItemClicked singleItemEventListener;

onAttach...
onCreateView...

@Override
public void onStart() {
    super.onStart();

    //Setting adapter
    onSetAdapter();
}

private void onSetAdapter() {
    List<Data> dataList;

    dataList = getData();

    adapter = new AdapterA(context, dataList, new OnItemClickListener() {
        @Override
        public void onItemClick(View view, int position) {
            singleItemEventListener.onSingleItemClicked(position);
        }
    });

In the Activity, we are implementing onSingleItemClicked callback to receive the event and launch FragmentB with data received from the interface callback:

ActivityA implements SingleItemEventListener {
@Override
    public void onSingleItemClicked(int position) {
Data data = getData(position);

if (data != null) {
Bundle bundle = new Bundle();
bundle.putParcelable("single_data_key", data);
Fragment fragmentB = fragmentManager.findFragmentByTag(FragmentB.class.getName());

        if (fragmentB == null && bundle != null) {
            fragmentB = Fragment.instantiate(this, FragmentB.class.getName(), bundle);
        }

        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        fragmentTransaction
                .replace(R.id.FragmentLayout, fragmentB, FragmentB.class.getName())
                .addToBackStack(FragmentB.class.getName())
                .commit();
}
}
}



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