Mimics behavior of Bottom Sheet in Android. From initial position, scrolling up disabled. If user scrolls more than half of view's height, view collapses. Otherwise, it goes back to its old position.

BottomSheetDragDownListener.java

import android.view.MotionEvent;
import android.view.View;
import android.view.animation.OvershootInterpolator;

public class BottomSheetDragDownListener implements View.OnTouchListener {

    private static final float INTERPOLATOR_FACTOR = 0.5f;
    private float dY, startScrollY, viewY;

    @Override
    public boolean onTouch(View view, MotionEvent event) {
        if (view == null){
            return false;
        }

        switch (event.getAction()) {

            case MotionEvent.ACTION_DOWN:
                startScrollY = event.getRawY();
                viewY = view.getY();

                dY = startScrollY - viewY;
                break;

            case MotionEvent.ACTION_MOVE:
                if (event.getRawY() > startScrollY) {
                    view.animate()
                            .y(event.getRawY() - dY)
                            .setDuration(0)
                            .start();
                }
                break;

            case MotionEvent.ACTION_UP:
                if (event.getRawY() > startScrollY) {
                    if ((event.getRawY() - startScrollY) < view.getHeight() / 2) {
                        view.animate()
                                .y(viewY)
                                .setInterpolator(new OvershootInterpolator(INTERPOLATOR_FACTOR))
                                .setDuration(200)
                                .start();
                    } else {
                        view.animate()
                                .y(viewY + view.getHeight())
                                .setDuration(200)
                                .setInterpolator(new OvershootInterpolator(INTERPOLATOR_FACTOR))
                                .start();
                    }
                }

            default:
                return false;
        }
        return true;
    }
}