CameraAppActivity.java
package my.apps.cameraApp;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import utils.fileWork;

import my.apps.cameraApp.R.id;
import android.app.Activity;
import android.content.Context;
import android.content.pm.PackageManager;
import android.hardware.Camera;
import android.hardware.Camera.PictureCallback;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.FrameLayout;
import android.widget.TextView;
import android.widget.Toast;


public class CameraAppActivity extends Activity {


	 private Camera mCamera;
	 private CameraPreview mPreview;

	 public static final int MEDIA_TYPE_IMAGE = 1;
	 fileWork fw = new fileWork();

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        // Create an instance of Camera
        mCamera = getCameraInstance();

        // Create our Preview view and set it as the content of our activity.
        mPreview = new CameraPreview(this, mCamera);


        FrameLayout preview = (FrameLayout) findViewById(id.camera_preview);

        preview.addView(mPreview);


      //Adding listener
        Button captureButton = (Button) findViewById(id.button_capture);
        captureButton.setOnClickListener(
        		new View.OnClickListener() {

 				@Override
 				public void onClick(View v) {
 					mCamera.takePicture(null, null, mPicture);



 				//	mCamera.stopPreview();HERE IS WHERE I GET THE ERROR
 				//	mCamera.startPreview();



 				}
 			});



        File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
	             Environment.DIRECTORY_PICTURES), "MyCameraApp");
        TextView nr = (TextView) findViewById(id.textView2);
        int len = mediaStorageDir.list().length;
        nr.setText( "Frames captured: " + Integer.toString(len));


    }



  //  @Override
   /* public void onBackPressed() {
    // do something on back.
    	mCamera.stopPreview();
    	mCamera.release();
    	// showMessage(this, "BAMBAM!");
    return;
    }*/


    PictureCallback mPicture = new PictureCallback() {

		@Override
		public void onPictureTaken(byte[] data, Camera camera) {
			 File pictureFile = getOutputMediaFile();
		        if (pictureFile == null){
		            return;
		        }

		        try {
		            FileOutputStream fos = new FileOutputStream(pictureFile);
		            fos.write(data);
		            fos.close();
		        } catch (FileNotFoundException e) {

		        } catch (IOException e) {

		        }

		}

	};


	public void showMessage(Context context, CharSequence text)
	{

		int duration = Toast.LENGTH_SHORT;

		Toast toast = Toast.makeText(context, text, duration);
		toast.show();

	}
	/** Create a File for saving the image */
	private static File getOutputMediaFile(){
		File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
	             Environment.DIRECTORY_PICTURES), "MyCameraApp");


	    if (! mediaStorageDir.exists()){
	        if (! mediaStorageDir.mkdirs()){
	            Log.d("MyCameraApp", "failed to create directory");
	            return null;
	        }
	    }

	    // Create a media file name
	    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
	    File mediaFile;
	        mediaFile = new File(mediaStorageDir.getPath() + File.separator +
	        "IMG_"+ timeStamp + ".jpg");

	    return mediaFile;
	}



    /** Check if this device has a camera */
    private boolean checkCameraHardware(Context context) {
        if (context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)){
            // this device has a camera
            return true;
        } else {
            // no camera on this device
            return false;
        }
    }

    /** A safe way to get an instance of the Camera object. */
    public static Camera getCameraInstance(){
        Camera c = null;
        try {
            c = Camera.open(1); // attempt to get a Camera instance
        }
        catch (Exception e){
            // Camera is not available (in use or does not exist)
        }
        return c; // returns null if camera is unavailable
    }
    private void releaseCamera(){
        if (mCamera != null){
            mCamera.release();        // release the camera for other applications
            mCamera = null;
        }
    }

    protected void onPause() {
        super.onPause();

     //   releaseCamera();              // release the camera immediately on pause event
    }


}



CameraPreview.java


package my.apps.cameraApp;


import java.io.IOException;

import android.content.Context;
import android.hardware.Camera;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

/** A basic Camera preview class */
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {

	private SurfaceHolder mSurfaceHolder;
	private Camera mCamera;

	//Constructor that obtains context and camera
	public CameraPreview(Context context, Camera camera) {
		super(context);
		this.mCamera = camera;

		this.mSurfaceHolder = this.getHolder();
		this.mSurfaceHolder.addCallback(this); // we get notified when underlying surface is created and destroyed
		this.mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); //this is a deprecated method, is not requierd after 3.0
	}

	@Override
	public void surfaceCreated(SurfaceHolder surfaceHolder) {
		try {
            mCamera.setPreviewDisplay(surfaceHolder);
            mCamera.startPreview();
        } catch (IOException e) {
          // left blank for now
        }

	}

	@Override
	public void surfaceDestroyed(SurfaceHolder surfaceHolder) {
		mCamera.stopPreview();
		mCamera.release();
	}

	@Override
	public void surfaceChanged(SurfaceHolder surfaceHolder, int format,
			int width, int height) {
		// start preview with new settings
		try {
			mCamera.setPreviewDisplay(surfaceHolder);
			mCamera.startPreview();
		} catch (Exception e) {
			// intentionally left blank for a test
		}
	}
	public SurfaceHolder getSurfaceHolder()
	{
		return this.mSurfaceHolder;
	}

}


The layout, main.xml


<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >

  <FrameLayout
      android:id="@+id/camera_preview"
      android:layout_width="138dp"
      android:layout_height="126dp" >

  </FrameLayout>


  <TextView
      android:id="@+id/textView1"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="Video surveillance"
      android:textAppearance="?android:attr/textAppearanceSmall" />

  <TextView
      android:id="@+id/textView2"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="Small Text"
      android:textAppearance="?android:attr/textAppearanceSmall" />


  <Button
      android:id="@+id/button_capture"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="Capture" />

</LinearLayout>