Change Extends Activity by Extends Fragment without affecting The result? (Android app)

I'm trying to merge two projects android.

The first is basically an Application that consists of a single Class: MainActivity.java

As I put below: (It's an example of how to upload an image of the Micro SD server yet)

@SuppressLint("NewApi")

public class MainActivity extends Activity
 {

    ProgressDialog prgDialog;

    String encodedString;

    RequestParams params = new RequestParams();
    String imgPath, fileName;
    Bitmap bitmap;
    private static int RESULT_LOAD_IMG = 1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        prgDialog = new ProgressDialog(this);
        // Set Cancelable as False
        prgDialog.setCancelable(false);
    }

    public void loadImagefromGallery(View view) {
        // Create intent to Open Image applications like Gallery, Google Photos
        Intent galleryIntent = new Intent(Intent.ACTION_PICK,
                android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
        // Start the Intent
        startActivityForResult(galleryIntent, RESULT_LOAD_IMG);
    }

    // When Image is selected from Gallery
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        try {
            // When an Image is picked
            if (requestCode == RESULT_LOAD_IMG && resultCode == RESULT_OK
                    && null != data) {
                // Get the Image from data

                Uri selectedImage = data.getData();
                String[] filePathColumn = { MediaStore.Images.Media.DATA };

                // Get the cursor
                Cursor cursor = getContentResolver().query(selectedImage,
                        filePathColumn, null, null, null);
                // Move to first row
                cursor.moveToFirst();

                int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
                imgPath = cursor.getString(columnIndex);
                cursor.close();
                ImageView imgView = (ImageView) findViewById(R.id.imgView);
                // Set the Image in ImageView
                imgView.setImageBitmap(BitmapFactory
                        .decodeFile(imgPath));
                // Get the Image's file name
                String fileNameSegments[] = imgPath.split("/");
                fileName = fileNameSegments[fileNameSegments.length - 1];
                // Put file name in Async Http Post Param which will used in Php web app
                params.put("filename", fileName);

            } else {
                Toast.makeText(this, "You haven't picked Image",
                        Toast.LENGTH_LONG).show();
            }
        } catch (Exception e) {
            Toast.makeText(this, "Something went wrong", Toast.LENGTH_LONG)
                    .show();
        }

    }

    // When Upload button is clicked
    public void uploadImage(View v) {
        // When Image is selected from Gallery
        if (imgPath != null && !imgPath.isEmpty()) {
            prgDialog.setMessage("Converting Image to Binary Data");
            prgDialog.show();
            // Convert image to String using Base64
            encodeImagetoString();
        // When Image is not selected from Gallery
        } else {
            Toast.makeText(
                    getApplicationContext(),
                    "You must select image from gallery before you try to upload",
                    Toast.LENGTH_LONG).show();
        }
    }

    // AsyncTask - To convert Image to String
    public void encodeImagetoString() {
        new AsyncTask<Void, Void, String>() {

            protected void onPreExecute() {

            };

            @Override
            protected String doInBackground(Void... params) {
                BitmapFactory.Options options = null;
                options = new BitmapFactory.Options();
                options.inSampleSize = 3;
                bitmap = BitmapFactory.decodeFile(imgPath,
                        options);
                ByteArrayOutputStream stream = new ByteArrayOutputStream();
                // Must compress the Image to reduce image size to make upload easy
                bitmap.compress(Bitmap.CompressFormat.PNG, 50, stream); 
                byte[] byte_arr = stream.toByteArray();
                // Encode Image to String
                encodedString = Base64.encodeToString(byte_arr, 0);
                return "";
            }

            @Override
            protected void onPostExecute(String msg) {
                prgDialog.setMessage("Calling Upload");
                // Put converted Image string into Async Http Post param
                params.put("image", encodedString);
                // Trigger Image upload
                triggerImageUpload();
            }
        }.execute(null, null, null);
    }

    public void triggerImageUpload() {
        makeHTTPCall();
    }

    // http://192.168.2.4:9000/imgupload/upload_image.php
    // http://192.168.2.4:9999/ImageUploadWebApp/uploadimg.jsp
    // Make Http call to upload Image to Php server
    public void makeHTTPCall() {
        prgDialog.setMessage("Invoking Php");       
        AsyncHttpClient client = new AsyncHttpClient();
        // Don't forget to change the IP address to your LAN address. Port no as well.
        client.post("http://192.168.2.5:9000/imgupload/upload_image.php",
                params, new AsyncHttpResponseHandler() {
                    // When the response returned by REST has Http
                    // response code '200'
                    @Override
                    public void onSuccess(String response) {
                        // Hide Progress Dialog
                        prgDialog.hide();
                        Toast.makeText(getApplicationContext(), response,
                                Toast.LENGTH_LONG).show();
                    }

                    // When the response returned by REST has Http
                    // response code other than '200' such as '404',
                    // '500' or '403' etc
                    @Override
                    public void onFailure(int statusCode, Throwable error,
                            String content) {
                        // Hide Progress Dialog
                        prgDialog.hide();
                        // When Http response code is '404'
                        if (statusCode == 404) {
                            Toast.makeText(getApplicationContext(),
                                    "Requested resource not found",
                                    Toast.LENGTH_LONG).show();
                        }
                        // When Http response code is '500'
                        else if (statusCode == 500) {
                            Toast.makeText(getApplicationContext(),
                                    "Something went wrong at server end",
                                    Toast.LENGTH_LONG).show();
                        }
                        // When Http response code other than 404, 500
                        else {
                            Toast.makeText(
                                    getApplicationContext(),
                                    "Error Occured \n Most Common Error: \n1. Device not connected to Internet\n2. Web App is not deployed in App server\n3. App server is not running\n HTTP Status code : "
                                            + statusCode, Toast.LENGTH_LONG)
                                    .show();
                        }
                    }
                });
    }

    @Override
    protected void onDestroy() {
        // TODO Auto-generated method stub
        super.onDestroy();
        // Dismiss the progress bar when application is closed
        if (prgDialog != null) {
            prgDialog.dismiss();
        }
    }
}

My question is: Would it be possible to convert this code to Fragment to add it to my other main project as an extension more than MainActivity ? .