How to change CollapsingToolbarLayout typeface in android programmatically

ScrollingActivity.java

package com.example.espl.collapsingtoolbarlayoutsetfont;

import android.graphics.Typeface;
import android.os.Bundle;
import android.support.design.widget.CollapsingToolbarLayout;
import android.support.v4.content.res.ResourcesCompat;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.widget.Button;

public class ScrollingActivity extends AppCompatActivity {

    CollapsingToolbarLayout toolbarLayout;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_scrolling);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        toolbarLayout=findViewById(R.id.toolbar_layout);
        Button btn=findViewById(R.id.btn);

        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                try {
//set custom font for CollapsingToolbarLayout title
                    Typeface typeface = ResourcesCompat.getFont(ScrollingActivity.this, R.font.work_sans_regular);
                    toolbarLayout.setCollapsedTitleTypeface(typeface);
                    toolbarLayout.setExpandedTitleTypeface(typeface);
                }catch (Exception e){
                    e.printStackTrace();
                }
            }
        });
    }
}

activity_scrolling.xml

<?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"
    android:fitsSystemWindows="true"
    tools:context=".ScrollingActivity">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/app_bar"
        android:layout_width="match_parent"
        android:layout_height="@dimen/app_bar_height"
        android:fitsSystemWindows="true"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.design.widget.CollapsingToolbarLayout
            android:id="@+id/toolbar_layout"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:fitsSystemWindows="true"
            app:contentScrim="?attr/colorPrimary"
            app:layout_scrollFlags="scroll|exitUntilCollapsed"
            app:toolbarId="@+id/toolbar">

            <android.support.v7.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="?attr/actionBarSize"
                app:layout_collapseMode="pin"
                app:popupTheme="@style/AppTheme.PopupOverlay" />

        </android.support.design.widget.CollapsingToolbarLayout>
    </android.support.design.widget.AppBarLayout>

    <android.support.v4.widget.NestedScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior">

        <LinearLayout
            android:orientation="vertical"
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <TextView
                android:text="@string/initial_large_text"
                android:layout_width="match_parent"
                android:layout_height="wrap_content" />

            <Button
                android:id="@+id/btn"
                android:text="Click to change the font for CollapsingToolbarLayout"
                android:layout_width="match_parent"
                android:layout_height="wrap_content" />

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_margin="@dimen/text_margin"
                android:text="@string/large_text" />

        </LinearLayout>
    </android.support.v4.widget.NestedScrollView>

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="@dimen/fab_margin"
        app:layout_anchor="@id/app_bar"
        app:layout_anchorGravity="bottom|end"
        app:srcCompat="@android:drawable/ic_dialog_email" />

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