Hide the BottomNavigationView when Scrolling Fragment

Question

I have a main activity layout comprising of a Toolbar,a Frame Layout, and a BottomNavigationView.

This is my main layout file of

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Toolbar ..>

    <FrameLayout ...>

    <android.support.design.widget.BottomNavigationView
        android:id="@+id/bottom_navigation_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom"
        app:menu="@menu/navigation" />

  </LinearLayout>

I inflate the main fragment which is RecyclerView with Cards. Now, I want the BottomNavigationView to be hidden when the user scrolls, but am unable to do it.

I tried this answer, but it doesn't work. Only a blank layout shows up and also many methods mentioned there are now deprecated.

Any help would be appreciated.

Answer 1

create a class called BottomNavigationBehavior

import android.content.Context;
import android.support.annotation.NonNull;
import android.support.design.widget.BottomNavigationView;
import android.support.design.widget.CoordinatorLayout;
import android.support.v4.view.ViewCompat;
import android.util.AttributeSet;
import android.view.View;
import android.widget.FrameLayout;

public class BottomNavigationBehavior extends CoordinatorLayout.Behavior<BottomNavigationView> {

    public BottomNavigationBehavior() {
        super();
    }

    public BottomNavigationBehavior(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    public boolean layoutDependsOn(CoordinatorLayout parent, BottomNavigationView child, @NonNull View dependency) {
        boolean dependsOn = dependency instanceof FrameLayout;
        return dependsOn;
    }

    @Override
    public boolean onStartNestedScroll(CoordinatorLayout coordinatorLayout, BottomNavigationView child, View directTargetChild, View target, int nestedScrollAxes) {
        return nestedScrollAxes == ViewCompat.SCROLL_AXIS_VERTICAL;
    }

    @Override
    public void onNestedPreScroll(CoordinatorLayout coordinatorLayout, BottomNavigationView child, View target, int dx, int dy, int[] consumed) {
        if (dy < 0) {
            showBottomNavigationView(child);
        } else if (dy > 0) {
            hideBottomNavigationView(child);
        }
    }

    private void hideBottomNavigationView(BottomNavigationView view) {
        view.animate().translationY(view.getHeight());
    }

    private void showBottomNavigationView(BottomNavigationView view) {
        view.animate().translationY(0);
    }
}

then call the class in your main activity like this

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activitymine);

       ...

        BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);

        // attaching bottom sheet behaviour - hide / show on scroll
        CoordinatorLayout.LayoutParams layoutParams = (CoordinatorLayout.LayoutParams) navigation.getLayoutParams();
        layoutParams.setBehavior(new BottomNavigationBehavior());

        ...
    }

or instead of calling it you can hook the class up with your bottom navigation straight from your xml code, like this

 <android.support.design.widget.BottomNavigationView
        android:id="@+id/navigation"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom"
        android:layout_marginStart="0dp"
        android:layout_marginEnd="0dp"
        android:background="?android:attr/windowBackground"
        app:itemBackground="@color/white"
        app:itemIconTint="@color/blue_700"
        app:itemTextColor="@color/blue_700"         app:layout_behavior="com.my.package.helper.BottomNavigationBehavior"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:menu="@menu/navigation" />

Anyhow it should work.

P.S that bottom navigation code was gotten from android hive, that guy is a genius. ;)