android BottomSheet how to collapse when clicked outside?

Finally I was able to do this,

Used the following lines of code:

@Override public boolean dispatchTouchEvent(MotionEvent event){
    if (event.getAction() == MotionEvent.ACTION_DOWN) {
        if (mBottomSheetBehavior.getState()==BottomSheetBehavior.STATE_EXPANDED) {

            Rect outRect = new Rect();
            bottomSheet.getGlobalVisibleRect(outRect);

            if(!outRect.contains((int)event.getRawX(), (int)event.getRawY()))
                mBottomSheetBehavior.setState(BottomSheetBehavior.STATE_COLLAPSED);
        }
    }

    return super.dispatchTouchEvent(event);
}

Hope it save someone's whole day!

For Activity:

@Override 
public boolean dispatchTouchEvent(MotionEvent event){
    if (event.getAction() == MotionEvent.ACTION_DOWN) {
        if (mBottomSheetBehavior.getState()==BottomSheetBehavior.STATE_EXPANDED) {

            Rect outRect = new Rect();
            bottomSheet.getGlobalVisibleRect(outRect);

            if(!outRect.contains((int)event.getRawX(), (int)event.getRawY()))
                mBottomSheetBehavior.setState(BottomSheetBehavior.STATE_COLLAPSED);
        }
    }

    return super.dispatchTouchEvent(event);
}

For Fragment: Use same method in Activity like,

@Override
public boolean dispatchTouchEvent(MotionEvent event) {
    if (event.getAction() == MotionEvent.ACTION_DOWN) {
        if (fragment != null && fragment instanceof HomeFragment) {
            ((HomeFragment) fragment).hideBottomSheetFromOutSide(event);
        }
    }
    return super.dispatchTouchEvent(event);
}

and Create Method in Fragment like:

   /**
     * Calling from Dashboard Activity
     *
     * @param event Motion Event
     */
    public void hideBottomSheetFromOutSide(MotionEvent event) {
        if (isBottomSheetMenuExpanded()) {
            Rect outRect = new Rect();
            mBinding.homeBottomSheetLayout.getGlobalVisibleRect(outRect);
            if (!outRect.contains((int) event.getRawX(), (int) event.getRawY()))
                mBottomSheetBehavior.setState(BottomSheetBehavior.STATE_COLLAPSED);
        }
    }

Hope it will helps you.

Thank you.

Thanks the OP for the question/answer. I've used his code but improved on its cleanliness and wanted to share. Instead of extending a View and adding the interface, you can code that directly in the BottomSheetBehavior. Like this:

AutoCloseBottomSheetBehavior.java

import android.content.Context;
import android.graphics.Rect;
import android.support.design.widget.BottomSheetBehavior;
import android.support.design.widget.CoordinatorLayout;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

public class AutoCloseBottomSheetBehavior<V extends View> extends BottomSheetBehavior<V> {

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

    @Override
    public boolean onInterceptTouchEvent(CoordinatorLayout parent, V child, MotionEvent event) {
        if (event.getAction() == MotionEvent.ACTION_DOWN &&
            getState() == BottomSheetBehavior.STATE_EXPANDED) {

            Rect outRect = new Rect();
            child.getGlobalVisibleRect(outRect);

            if (!outRect.contains((int) event.getRawX(), (int) event.getRawY())) {
                setState(BottomSheetBehavior.STATE_COLLAPSED);
            }
        }
        return super.onInterceptTouchEvent(parent, child, event);
    }
}

and then you simply add it to your XML layout:

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
    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:layout_width="match_parent"
    android:layout_height="match_parent">

   ... your normal content here ...
   <SomeLayout... />

    ... the bottom sheet with the behavior
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        app:layout_behavior="<com.package.name.of.the.class>.AutoCloseBottomSheetBehavior">

        ... the bottom sheet views

    </LinearLayout>

</android.support.design.widget.CoordinatorLayout>