Trying to build an app to display photos from a gallery using XML and JSON

/*MainActivity-Gautham Ravi Prakash*/
package com.example.threadshw4;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class MainActivity extends Activity {
    Button photos, slideShow;
    public static final String PHOTO_ACTIVITY = "Photo Activity";
    public static final int PHOTO_DISPLAY_MODE_NUMBER = 1;
    public static final int SLIDE_SHOW_MODE_NUMBER = 2;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        this.setTitle(R.string.MainClass_title_activity);

        photos = (Button) findViewById(R.id.button1);
        slideShow = (Button) findViewById(R.id.button2);

        final Intent intent = new Intent(MainActivity.this, PhotoActivity.class);

        photos.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View view) {
                // TODO Auto-generated method stub
                intent.putExtra(PHOTO_ACTIVITY, PHOTO_DISPLAY_MODE_NUMBER);
                startActivity(intent);
            }
        });

        slideShow.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                intent.putExtra(PHOTO_ACTIVITY, SLIDE_SHOW_MODE_NUMBER);
                startActivity(intent);
            }
        });
    }

    @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;
    }

}

/*PhotoActivity-Gautham Ravi Prakash*/
package com.example.threadshw4;

import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import javax.security.auth.callback.Callback;

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.app.Activity;
import android.app.ProgressDialog;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.util.Log;
import android.view.Menu;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.ImageView;

public class PhotoActivity extends Activity {
    ImageView photoImageView;
    Handler hander, handlerSlideShow;
    ProgressDialog progressDialog;
    ExecutorService photoPool, photoPoolSlideShow;
    public static final String TAG = PhotoActivity.class.getSimpleName();
    public String[] urlList = null;
    public int photoId = 0;
    public static final int PHOTO_DISPLAY_MODE_NUMBER = 1;
    public static final int SLIDE_SHOW_MODE_NUMBER = 2;
    Photo photo;
    PhotoSlideShow photoSlideShow;
    InputStream inputStream = null;
    public static final String KEY = "Image";
    Message message = null;
    Bitmap bitmap = null;
    Bundle bundle = null;
    public float x = 0;
    public int a = 1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_photo);
        this.setTitle(R.string.SecondClass_activity_photo);

        photoImageView = (ImageView) findViewById(R.id.imageView1);
        urlList = getResources().getStringArray(R.array.photo_urls);

        photoPool = Executors.newFixedThreadPool(1);
        photoPoolSlideShow = Executors.newFixedThreadPool(1);

        progressDialog = new ProgressDialog(this);
        progressDialog.setMessage("Loading Image...");
        progressDialog.setCancelable(false);

        hander = new Handler(new Handler.Callback() {

            @Override
            public boolean handleMessage(Message msg) {
                // TODO Auto-generated method stub
                bitmap = (Bitmap) msg.getData().get(KEY);
                photoImageView.setImageBitmap(bitmap);
                progressDialog.dismiss();

                return false;
            }
        });

        handlerSlideShow = new Handler(new Handler.Callback() {

            @Override
            public boolean handleMessage(Message msg) {
                // TODO Auto-generated method stub
                bitmap = (Bitmap) msg.getData().get(KEY);
                photoImageView.setImageBitmap(bitmap);

                return false;
            }
        });

        if (getIntent().getExtras().getInt(MainActivity.PHOTO_ACTIVITY) == PHOTO_DISPLAY_MODE_NUMBER) {

            getPhoto(photoId);

            photoImageView.setOnTouchListener(new OnTouchListener() {

                @Override
                public boolean onTouch(View arg0, MotionEvent motionEvent) {
                    // TODO Auto-generated method stub
                    x = motionEvent.getX();

                    if (x < 0.2 * photoImageView.getWidth()) {
                        photoId = (photoId + urlList.length - 1)
                                % urlList.length;
                    } else if (x > 0.8 * photoImageView.getWidth()) {
                        photoId = (photoId + 1) % urlList.length;
                    }
                    getPhoto(photoId);
                    return false;
                }
            });

        } else if (getIntent().getExtras().getInt(MainActivity.PHOTO_ACTIVITY) == SLIDE_SHOW_MODE_NUMBER) {

            getPhotoSlideShow(photoId);

        }

    }

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

    public void getPhoto(int photoId) {
        // TODO Auto-generated method stub
        photo = new Photo(String.valueOf(photoId), urlList[photoId]);
        photoPool.execute(photo);
        progressDialog.show();

    }

    public void getPhotoSlideShow(int photoId) {
        // TODO Auto-generated method stub
        photoSlideShow = new PhotoSlideShow(photoId, urlList[photoId]);
        photoPoolSlideShow.execute(photoSlideShow);

        // getPhotoSlideShow(photoId);
    }

    public class Photo implements Runnable {
        String photoId, url;

        public Photo(String photoId, String url) {
            super();
            this.photoId = photoId;
            this.url = url;
        }

        @Override
        public void run() {
            // TODO Auto-generated method stub
            try {
                inputStream = new java.net.URL(url).openStream();
                bitmap = BitmapFactory.decodeStream(inputStream);
                bundle = new Bundle();
                bundle.putParcelable(KEY, bitmap);
                message = new Message();
                message.setData(bundle);
                hander.sendMessage(message);

            } catch (MalformedURLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                Log.e(TAG, "malformed URL exception caught : ", e);
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                Log.e(TAG, "IO exception caught : ", e);
            }

        }

    }

    public class PhotoSlideShow implements Runnable {
        int photoId;
        String url;

        public PhotoSlideShow(int photoId, String url) {
            super();
            this.photoId = photoId;
            this.url = url;
        }

        @Override
        public void run() {
            // TODO Auto-generated method stub
            try {
                while(photoId != urlList.length){

                inputStream = new java.net.URL(urlList[photoId++]).openStream();
                bitmap = BitmapFactory.decodeStream(inputStream);
                bundle = new Bundle();
                bundle.putParcelable(KEY, bitmap);
                message = new Message();
                message.setData(bundle);
                hander.sendMessage(message);

                Thread.sleep(2000);

                if (photoId == urlList.length) {
                    photoId = 0;
                }
                }
            } catch (MalformedURLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                Log.e(TAG, "malformed URL exception caught : ", e);
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                Log.e(TAG, "IO exception caught : ", e);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        }

    }
}