Check out example codes for "how to stop screen rotation in android code". It will help you in understanding the concepts better.

Code Example 1

<!-- inside of your AndroidManifest.xml -->
<activity android:name=".MainActivity"
		  android:screenOrientation="portrait"/>

Code Example 2

android:screenOrientation="portrait"

Code Example 3

<activity
        ...
        ...
        android:screenOrientation="nosensor">

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