<activity

        ...

        ...

        android:screenOrientation="nosensor">

android:screenOrientation="portrait" 

//put this <

this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);

 // > In your MainActivity.java

<!-- inside of your AndroidManifest.xml -->

<activity android:name=".MainActivity"

          android:screenOrientation="portrait"/>

android:screenOrientation="portrait or landscape"