How to indicate a default button in Material Design

1. Why there is three types of button in material design?
2. How to change default button style in Android Studio?

Why there is three types of button in material design?

There are text, contained, and toggle buttons. Text buttons are typically used for less important actions. Outlined buttons are used for more emphasis than text buttons due to the stroke. Contained buttons have more emphasis, as they use a color fill and shadow.

How to change default button style in Android Studio?

To change the default Button style of the application we can use the android:buttonStyle attribute in the AppTheme style inside the styles. xml.