activity_main.xmltoolbar.xmlsimonetta.xmlstyles.xmlMainActivity.java
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center_horizontal"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <include
        android:id="@+id/toolbar"
        layout="@layout/toolbar" />

    <TextView
        android:id="@+id/text_view_1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:fontFamily="@font/simonetta"
        android:text="Hello World!"
        android:textSize="30sp" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:fontFamily="@font/simonetta"
        android:text="Hello World!"
        android:textSize="30sp"
        android:textStyle="italic" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:fontFamily="@font/simonetta"
        android:text="Hello World!"
        android:textSize="30sp"
        android:textStyle="bold" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:fontFamily="@font/simonetta"
        android:text="Hello World!"
        android:textSize="30sp"
        android:textStyle="bold|italic" />

</LinearLayout>
<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.Toolbar xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@color/colorPrimary"
    android:elevation="4dp"
    android:theme="@style/ToolbarThemeOverlay"
    app:popupTheme="@style/ThemeOverlay.AppCompat.Light">

</android.support.v7.widget.Toolbar>
<?xml version="1.0" encoding="utf-8"?>
<font-family xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <font
        app:font="@font/simonetta_regular"
        app:fontStyle="normal"
        app:fontWeight="400" />
    <font
        app:font="@font/simonetta_italic"
        app:fontStyle="italic"
        app:fontWeight="400" />
    <font
        app:font="@font/simonetta_black"
        app:fontStyle="normal"
        app:fontWeight="700" />
    <font
        app:font="@font/simonetta_black_italic"
        app:fontStyle="italic"
        app:fontWeight="700" />
</font-family>
<resources>

    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
        <item name="android:fontFamily">@font/simonetta</item>
    </style>

    <style name="ToolbarThemeOverlay" parent="@style/ThemeOverlay.AppCompat.Dark.ActionBar">
        <item name="android:fontFamily">@font/architects_daughter</item>
    </style>
    
</resources>
package com.codinginflow.fontsexample;

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

public class MainActivity extends AppCompatActivity {

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

        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        final TextView textView = findViewById(R.id.text_view_1);
        final Typeface typeface = ResourcesCompat.getFont(this, R.font.architects_daughter);

        textView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                textView.setTypeface(typeface);
            }
        });
    }
}