MainActivity

package com.googlecardboard.googlecardboard;

import android.support.v7.app.ActionBarActivity;
import android.app.Activity;
import android.graphics.Camera;
import android.hardware.Camera.CameraInfo;
import android.media.MediaRecorder;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.Surface;
import android.view.SurfaceView;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends ActionBarActivity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}

	@Override
	public boolean onOptionsItemSelected(MenuItem item) {
		// Handle action bar item clicks here. The action bar will
		// automatically handle clicks on the Home/Up button, so long
		// as you specify a parent activity in AndroidManifest.xml.
		int id = item.getItemId();
		if (id == R.id.action_settings) {
			return true;
		}
		return super.onOptionsItemSelected(item);
	}

	public void onButtonClick(View v) {
		EditText inputText = (EditText) findViewById(R.id.input_text);
        String message = inputText.getText().toString();
		Toast.makeText(this, message, Toast.LENGTH_LONG).show();
	}

	public static void setCameraDisplayOrientation(Activity activity,
	    int cameraId, android.hardware.Camera camera) {
	    android.hardware.Camera.CameraInfo info =
	         new android.hardware.Camera.CameraInfo();
	    android.hardware.Camera.getCameraInfo(cameraId, info);
	    int rotation = activity.getWindowManager().getDefaultDisplay()
	         .getRotation();
	    int degrees = 0;
	    switch (rotation) {
	        case Surface.ROTATION_0: degrees = 0; break;
	        case Surface.ROTATION_90: degrees = 90; break;
	        case Surface.ROTATION_180: degrees = 180; break;
	        case Surface.ROTATION_270: degrees = 270; break;
	    }

	    int result;
	    if (info.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
	        result = (info.orientation + degrees) % 360;
	        result = (360 - result) % 360;  // compensate the mirror
	    } else {  // back-facing
	        result = (info.orientation - degrees + 360) % 360;
	    }
	    camera.setDisplayOrientation(result);
    }

	public class CameraActivity extends Activity {
	    private Camera mCamera;
	    private SurfaceView mPreview;
	    private MediaRecorder mMediaRecorder;

	    @Override
	    protected void onPause() {
	        super.onPause();
	        releaseMediaRecorder();       // if you are using MediaRecorder, release it first
	        releaseCamera();              // release the camera immediately on pause event
	    }

	    @SuppressWarnings("deprecation")
		private void releaseMediaRecorder(){
	        if (mMediaRecorder != null) {
	            mMediaRecorder.reset();   // clear recorder configuration
	            mMediaRecorder.release(); // release the recorder object
	            mMediaRecorder = null;
	            ((android.graphic.Camera) mCamera).lock();           // lock camera for later use
	        }
	    }

	    private void releaseCamera(){
	        if (mCamera != null){
	            ((android.hardware.Camera) mCamera).release();        // release the camera for other applications
	            mCamera = null;
	        }
	    }
	}
}