How to add new activity to existing project in Android Studio?

In Android Studio 2, just right click on app and select New > Activity > ... to create desired activity type.

I think natually do it is straightforward, whether Intellij IDEA or Android Studio, I always click new Java class menu, and then typing the class name, press Enter to create. after that, I manually typing "extends Activity" in the class file, and then import the class by shortcut key. finally, I also manually override the onCreate() method and invoke the setContentView() method.

To add an Activity using Android Studio.

This step is same as adding Fragment, Service, Widget, and etc. Screenshot provided.

[UPDATE] Android Studio 3.5. Note that I have removed the steps for the older version. I assume almost all is using version 3.x.

1. Right click either java package/java folder/module, I recommend to select a java package then right click it so that the destination of the Activity will be saved there
2. Select/Click New
3. Select Activity
4. Choose an Activity that you want to create, probably the basic one.

To add a Service, or a BroadcastReceiver, just do the same step.