Introduction

You generally do not change the ActionBar title font through one direct ActionBar API call. The usual solution is to use a Toolbar and supply a custom title view or style the title through a theme where possible, because modern Android UI customization is much easier with Toolbar than with the old built-in ActionBar.

Prefer Toolbar Over the Old ActionBar

In modern Android apps, the practical answer is usually to use Toolbar as the app bar.

1<androidx.appcompat.widget.Toolbar
2    android:id="@+id/toolbar"
3    android:layout_width="match_parent"
4    android:layout_height="wrap_content" />

Then set it up in the activity.

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

Once you control the toolbar directly, custom fonts become much easier.

Use a Custom Title View When You Need Full Control

A common pattern is to place a TextView in the toolbar and apply the desired font there.

1<TextView
2    android:id="@+id/toolbarTitle"
3    android:layout_width="wrap_content"
4    android:layout_height="wrap_content"
5    android:text="My Screen"
6    android:fontFamily="@font/my_custom_font" />

This is often cleaner than trying to coerce old ActionBar title APIs into behavior they were never designed to expose flexibly.

Keep the Font in Resources

With modern Android resource support, fonts belong in res/font rather than being loaded from arbitrary asset paths when possible. That keeps the setup more consistent with the rest of the resource system.

Common Pitfalls

• Trying to customize the legacy ActionBar title directly when a Toolbar would be easier to control.
• Mixing old ActionBar APIs and AppCompat toolbar patterns in the same screen.
• Applying a custom font to a title view but forgetting to disable or replace the default title handling.
• Treating font customization as only a code problem instead of also a layout and theme design choice.
• Hard-coding font-loading patterns when Android resource fonts are the better fit.

Summary

• The practical modern answer is to use a Toolbar, not depend on old ActionBar title customization.
• A custom title TextView gives the most control over font styling.
• Keep the font in Android resources when possible.
• Treat title styling as part of toolbar design, not just as one API call.
• The easier path is usually replacing the title view rather than fighting legacy ActionBar limitations.