I want my android application to be only run in portrait mode?

In Android Manifest File, put attribute for your <activity> that android:screenOrientation="portrait"

In the manifest, set this for all your activities:

<activity android:name=".YourActivity"
    android:configChanges="orientation"
    android:screenOrientation="portrait"/>

Let me explain:

• With android:configChanges="orientation" you tell Android that you will be responsible of the changes of orientation.
• android:screenOrientation="portrait" you set the default orientation mode.