app/src/main/java/org/apache/fineract/utils/ScrollFabBehavior.java

package org.apache.fineract.utils;

import android.content.Context;
import androidx.coordinatorlayout.widget.CoordinatorLayout;
import com.google.android.material.floatingactionbutton.FloatingActionButton;
import androidx.core.view.ViewCompat;
import android.util.AttributeSet;
import android.view.View;

public class ScrollFabBehavior extends FloatingActionButton.Behavior {

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

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

    @Override
    public void onNestedScroll(CoordinatorLayout coordinatorLayout, FloatingActionButton child,
            View target, int dxConsumed, int dyConsumed, int dxUnconsumed,
            int dyUnconsumed) {
        super.onNestedScroll(coordinatorLayout, child, target, dxConsumed, dyConsumed, dxUnconsumed,
                dyUnconsumed);
        if (dyConsumed > 0 && child.getVisibility() == View.VISIBLE) {
            // Reason to set fab visiblity as INVISIBLE :
            // https://stackoverflow.com/a/41386278/4672688
            child.hide(new FloatingActionButton.OnVisibilityChangedListener() {
                @Override
                public void onHidden(FloatingActionButton fab) {
                    super.onHidden(fab);
                    fab.setVisibility(View.INVISIBLE);
                }
            });
        } else if (dyConsumed < 0 && child.getVisibility() != View.VISIBLE) {
            child.show();
        }
    }
}