Ytukyg

So I am trying to implement a FAB button such that, when I scroll my recycler view and the first item is not visible (scrolled up etc) , fab button should be visible, else it should be hidden if the first position is showing. Right now I have implemented the code, but it doesn't show the fab button at all, just wanted to know what I am doing wrong?

my xml code is below:

<Linearlayout ....





    <FrameLayout

            android:layout_width="match_parent"

            android:layout_height="match_parent">

        <android.support.v4.widget.SwipeRefreshLayout

            xmlns:android="http://schemas.android.com/apk/res/android"

            android:id="@+id/pullToRefreshLayout"

            android:layout_width="match_parent"

            android:layout_height="match_parent">



            <android.support.v7.widget.RecyclerView

                android:id="@+id/myRecyclerView"

                android:layout_width="match_parent"

                android:layout_height="match_parent" />



        </android.support.v4.widget.SwipeRefreshLayout>



            <android.support.design.widget.FloatingActionButton

                android:id="@+id/emailFab"

                android:layout_width="wrap_content"

                android:layout_height="wrap_content"

                android:layout_margin="16dp"

                android:src="@android:drawable/ic_dialog_email"

                app:layout_anchor="@id/myRecyclerView"

                android:layout_gravity="bottom|end"

                app:layout_behavior="com.example.fab.ScrollAwareFABBehavior"

                app:layout_anchorGravity="bottom|end"

                />

        </FrameLayout>



</LinearLayout>

my Kotlin code is below:

val positionView = (myRecyclerView.getLayoutManager() as LinearLayoutManager).findFirstVisibleItemPosition()



myRecyclerView.addOnScrollListener(object : RecyclerView.OnScrollListener() {

            override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {

                super.onScrolled(recyclerView, dx, dy)

                if (dy >0 && positionView > 0) {

                    emailFab.show();

                } else  {

                    emailFab.hide();

                }

            }

Any ideas how to go about it?

Thanks!

I think the problem is that you should pull the findFirstVisibleItemPosition() into the OnScrollListener to find visible position in scroll changes:

myRecyclerView.addOnScrollListener(object : RecyclerView.OnScrollListener() {



        override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {

            super.onScrolled(recyclerView, dx, dy)



            val positionView = (myRecyclerView.getLayoutManager() as LinearLayoutManager).findFirstVisibleItemPosition()



            if (positionView > 0) {

                if(!emailFab.isShown) {

                    emailFab.show();

                }

            } else  {

                if(emailFab.isShown) {

                    emailFab.hide();

                }

            }

        }

    })

this code is 100% working

public class TestActivity extends AppCompatActivity {



private static final String TAG = "TestActivity";



private ArrayList<String> datas = new ArrayList<>();



private FloatingActionButton fabButton;

private RecyclerView recyclerView;

private LinearLayoutManager linearLayoutManager;

private DataAdapter dataAdapter;



private boolean isFabVisible = false;



private OnFabVisibilityCallback onFabVisibilityCallback;



public void setOnFabVisibilityCallback(OnFabVisibilityCallback onFabVisibilityCallback) {

    this.onFabVisibilityCallback = onFabVisibilityCallback;

}



@Override

protected void onCreate(@Nullable Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_test_contacts);



    datas.add("one");

    datas.add("two");

    datas.add("three");

    datas.add("four");

    datas.add("five");

    datas.add("six");

    datas.add("seven");

    datas.add("eight");

    datas.add("nine");

    datas.add("ten");



    fabButton = (FloatingActionButton)findViewById(R.id.fabButton);

    fabButton.setVisibility(View.GONE);

    recyclerView = (RecyclerView)findViewById(R.id.recyclerView);

    linearLayoutManager = new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false);

    recyclerView.setLayoutManager(linearLayoutManager);

    dataAdapter = new DataAdapter(this, datas);

    recyclerView.setAdapter(dataAdapter);





    recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {

        @Override

        public void onScrolled(RecyclerView recyclerView, int dx, int dy) {



            if(linearLayoutManager.findFirstVisibleItemPosition() == 0){

                //hide

                if(onFabVisibilityCallback != null){

                    onFabVisibilityCallback.onChange(false);

                }

            }else{

                //show

                if(onFabVisibilityCallback != null){

                    onFabVisibilityCallback.onChange(true);

                }

            }



        }

    });



    setOnFabVisibilityCallback(new OnFabVisibilityCallback() {

        @Override

        public void onChange(boolean isVisible) {

            if(isVisible){

                if(!isFabVisible){

                    isFabVisible = true;

                    fabButton.setVisibility(View.VISIBLE);

                }

            }else{

                if(isFabVisible){

                    isFabVisible = false;

                    fabButton.setVisibility(View.GONE);

                }

            }

        }

    });



}



private class DataAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder>{



    private Activity activity;

    private ArrayList<String> datas;

    private LayoutInflater layoutInflater;



    public DataAdapter(Activity activity, ArrayList<String> datas) {

        this.activity = activity;

        this.datas = datas;

        this.layoutInflater = LayoutInflater.from(activity);

    }



    @NonNull

    @Override

    public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {

        return new SimpleViewHolder(layoutInflater.inflate(R.layout.unit_test, parent, false));

    }



    @Override

    public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {

        ((SimpleViewHolder)holder).init(datas.get(position));

    }



    @Override

    public int getItemCount() {

        return datas.size();

    }



    private class SimpleViewHolder extends RecyclerView.ViewHolder{



        private TextView text;



        public SimpleViewHolder(View itemView) {

            super(itemView);

            initViews(itemView);

        }



        private void initViews(View v){

            text = (TextView)v.findViewById(R.id.text);

        }



        public void init(String data){

            text.setText(data);

        }



    }



}



public interface OnFabVisibilityCallback{



    void onChange(boolean isVisible);



}

}

the activity layout files

    <?xml version="1.0" encoding="utf-8"?>

<RelativeLayout

    xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="match_parent"

    android:layout_height="match_parent">



    <android.support.v7.widget.RecyclerView

        android:id="@+id/recyclerView"

        android:layout_width="match_parent"

        android:layout_height="match_parent"/>



    <android.support.design.widget.FloatingActionButton

        android:id="@+id/fabButton"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_alignParentBottom="true"

        android:layout_alignParentRight="true"

        android:layout_margin="16dp"

        android:src="@drawable/ic_add_black_24dp"

        android:tint="@color/white" />



</RelativeLayout>

this is recyclerview child layout

    <?xml version="1.0" encoding="utf-8"?>

<LinearLayout

    android:gravity="center"

    android:background="@color/yellow"

    xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="match_parent"

    android:layout_height="150dp">



    <TextView

        android:text="data"

        android:id="@+id/text"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content" />



</LinearLayout>

if some problem occurs leme know :)
happy coding