Force an Android activity to always use landscape mode

Looking at the AndroidManifest.xml (link), on line 9:

<activity android:screenOrientation="landscape" android:configChanges="orientation|keyboardHidden" android:name="VncCanvasActivity">

This line specifies the screenOrientation as landscape, but author goes further in overriding any screen orientation changes with configChanges="orientation|keyboardHidden". This points to a overridden function in VncCanvasActivity.java.

If you look at VncCanvasActivity, on line 109 is the overrided function:

@Override
public void onConfigurationChanged(Configuration newConfig) {
  // ignore orientation/keyboard change
  super.onConfigurationChanged(newConfig);
}

The author specifically put a comment to ignore any keyboard or orientation changes.

If you want to change this, you can go back to the AndroidManifest.xml file shown above, and change the line to:

<activity android:screenOrientation="sensor" android:name="VncCanvasActivity">

This should change the program to switch from portrait to landscape when the user rotates the device.

This may work, but might mess up how the GUI looks, depending on how the layout were created. You will have to account for that. Also, depending on how the activities are coded, you may notice that when screen orientation is changed, the values that were filled into any input boxes disappear. This also may have to be handled.

You can set the same data in your java code as well.

myActivity.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);

Other values on ActivityInfo will let you set it back to sensor driven or locked portrait. Personally, I like to set it to something in the Manifest as suggested in another answer to this question and then change it later using the above call in the Android SDK if there's a need.

In my OnCreate(Bundle), I generally do the following:

this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);

You can specify the orientation of an activity in the manifest. See here.

<activity android:allowTaskReparenting=["true" | "false"]
...
          android:screenOrientation=["unspecified" | "user" | "behind" |
                                     "landscape" | "portrait" |
                                     "sensor" | "nosensor"]
...
                                       "adjustResize", "adjustPan"] >