Circular Progress

From google material design documentation.

Minimize visual changes that occur while your app loads content by representing each operation with a single activity indicator. For example, a refresh operation should display either a refresh bar or an activity circle, but not both.

How to add?

I. In your build.gradle add latest appcompat library.

dependencies {  
    compile 'com.android.support:appcompat-v7:X.X.X' // where X.X.X version
}

II. Make your activity extend. android.support.v7.app.AppCompatActivity.

public class MainActivity extends AppCompatActivity {  
    ...
}

III. Declare your ProgressBar inside any layout.xml file.

<ProgressBar  
    style="@style/Widget.AppCompat.ProgressBar"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"/>

How to style?

I. Declare custom style in your styles.xml file.

<style name="CircularProgress" parent="Theme.AppCompat.Light">  
    <item name="colorAccent">@color/indigo</item>
</style>  

II. Apply this style to your ProgressBar via android:theme attribute.

<ProgressBar  
    android:theme="@style/CircularProgress"
    style="@style/Widget.AppCompat.ProgressBar"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"/>

Compatibility issues

ProgressBar is not displayed in material style on pre Lollipop devices.