No Launcher activity found!

After learning about android, I created two projects. Today, when I created a new android project to run the program, the error "No Launcher activity found" is displayed, and the simulator is not running.
I checked the Internet and found that the problem lies in the main configuration xml of the entire project. Generally, the name is AndroidManifest. xml.
No startup Item is configured in it (for a variety of reasons). This code is missing in <application> </application>.
<Activity android: name = ". MainActivity" android: label = "@ string/app_name">
<Intent-filter>
<Action android: name = "android. intent. action. MAIN"/>
<Category android: name = "android. intent. category. LAUNCHER"/>
</Intent-filter>
</Activity>