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

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.

android screen-orientation

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

android screen-orientation

There are two ways,

Add android:screenOrientation="portrait" for each Activity in Manifest File
Add this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE); in each java file.

CodeHunter