مشکل با برنامه ی ImageOptimization

سلام دوستان، من کدها رو تا اون قسمت که عکس ها دانلود میشن و داخل فایل temp ریخته میشن رو نوشتم ولی دوتا مشکل دارم : اول اینکه وقتی برنامه رو ران می کنم همون اولش روی امولیتورم لیست ویو نمایش داده نمیشه و باید back بزنم و دوباره برنامه رو باز کنم بعدش لیست ویو توی امولیتور نمایش داده میشه . دوم اینکه در امولیتور من 7 تا ایمیج جا میگیره که همون اولش هیچ کدوم از این 7 تا دانلود نمیشن و وقتی به سمت پایین اسکرول میکنم بقیه ی عکس ها از شماره 8 تا اخرش که 11 هست فقط دانلود میشن . مشکل کد من کجاست ؟؟ کد کلاس های مهم رو میزارم . ممنون

 // Codes of G class: 

package com.example.n5110.imageoptimization;

import android.app.Application;
import android.content.Context;
import android.os.Environment;
import android.os.Handler;
import java.io.File;


public class G extends Application {

    public static Context context;
    private static G instance;
    public static String resultResponse;

    public static final String DIR_SDCARD = Environment.getExternalStorageDirectory().getAbsolutePath();
    public static final String DIR_APP = DIR_SDCARD + "/image-optimization";
    public static final String DIR_TEMP = DIR_APP + "/temp";
    public static final int DOWNLOAD_BUFFER_SIZE = 8 * 1024;
    public static final Handler HANDLER = new Handler();

    public static G getInstance() {
        return instance;
    }

    @Override
    public void onCreate() {
        super.onCreate();

        new File(DIR_APP).mkdirs();
        new File(DIR_TEMP).mkdirs();

        DownloadManager.initialize();

        instance = this;
        context = getApplicationContext();
    }
}

// Codes of AdapterImage class:

package com.example.n5110.imageoptimization;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import java.util.ArrayList;


public class AdapterImage extends BaseAdapter {
    private Context context;
    private ArrayList<StructImage> data;
    private LayoutInflater inflater;

    public AdapterImage(Context context, ArrayList<StructImage> data) {
        this.context = context;
        this.data = data;
        inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    public static class ViewHolder {
        public ViewGroup layout_root;
        public TextView txt_title;
        public ImageView img_preview;

    }

    @Override
    public int getCount() {
        return data.size();
    }

    @Override
    public Object getItem(int position) {
        return position;
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        View vi = convertView;
        ViewHolder holder = new ViewHolder();

        if (vi==null) {
            vi = inflater.inflate(R.layout.adapter_image, null);
            holder.layout_root = (ViewGroup)vi.findViewById(R.id.layout_root);
            holder.txt_title = (TextView)vi.findViewById(R.id.txt_title);
            holder.img_preview = (ImageView)vi.findViewById(R.id.img_preview);
            vi.setTag(holder);

        } else {
            holder = (ViewHolder) vi.getTag();
        }

        if (data.size() > 0){
            StructImage tempValue = data.get(position);
            holder.txt_title.setText(tempValue.getTitle());
//            holder.img_preview.set
        }

        DownloadManager.addToDownloadList(data.get(position).getImageUrl());
        return vi;
    }
}

//Codes of ActivityStartup class:

package com.example.n5110.imageoptimization;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ListView;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;


public class ActivityStartup extends AppCompatActivity {

    private OnDownloadCompleteListener listener;

    public ListView list;
    public AdapterImage adapter;
    public ArrayList<StructImage> images = new ArrayList<StructImage>();

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

        list = (ListView)findViewById(R.id.list);
        adapter = new AdapterImage(this, images);
        list.setAdapter(adapter);

        getImageListFromServer();

    }

    private void getImageListFromServer(){
        Webservice.readUrl(this, "http://192.168.1.33/file-server/service.php");

        if (G.getInstance().resultResponse != null) {
            try {
                images.clear();
                JSONArray tasks = new JSONArray(G.getInstance().resultResponse);
                for (int i = 0; i < tasks.length(); i++) {
                    JSONObject object = tasks.getJSONObject(i);
                    images.add( new StructImage(object.getString("title"), object.getString("url")));
                }
                adapter.notifyDataSetChanged();

            } catch (JSONException e) {
                e.printStackTrace();
            }
        }
    }
}

//Codes of DownloadManager class:

package com.example.n5110.imageoptimization;

import android.os.AsyncTask;
import android.util.Log;
import android.widget.Toast;
import java.util.ArrayList;


public class DownloadManager {
    public static ArrayList<String> urls = new ArrayList<String>();
    public static String myUrl;
    public static OnDownloadCompleteListener downloadCompleteListener;

    public static void initialize(){
        downloadCompleteListener = new OnDownloadCompleteListener() {
            @Override
            public void onDownloadComplete(String url, String localPath) {
                Log.i("LOG", "Image Download Complete, Original URL: " + url + ", Save Path: " + localPath);
            }
        };
    }

    public static void addToDownloadList(String url){
        myUrl = url;
        if (urls.contains(myUrl)){
            return;
        }
        urls.add(myUrl);
        new DownloadFile().execute();
    }

    static class DownloadFile extends AsyncTask<Void, Void, Void> {

        @Override
        protected Void doInBackground(Void... params) {
            String localFileName = myUrl.replace("/images/", "/");
            FileDownloader.download("http://192.168.1.33/file-server/" + myUrl, G.DIR_TEMP + localFileName, downloadCompleteListener);

            return null;
        }
        @Override
        protected void onPostExecute(Void aVoid) {
            Toast.makeText(G.context, "Finish", Toast.LENGTH_SHORT).show();
        }
    }
}

//Codes of FileDownloader class:

package com.example.n5110.imageoptimization;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;


public class FileDownloader {
    public static void download(final String downloadPath, final String filepath, final OnDownloadCompleteListener listener) {
        Thread thread = new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    URL url = new URL(downloadPath);
                    HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                    connection.setRequestMethod("GET");
                    connection.setDoOutput(true);
                    connection.connect();

                    File file = new File(filepath);
                    if (file.exists()){
                        file.delete();
                    }

                    FileOutputStream outputStream = new FileOutputStream(filepath);

                    InputStream inputStream = connection.getInputStream();
                    byte[] buffer = new byte[G.DOWNLOAD_BUFFER_SIZE];
                    int len = 0;
                    while ((len = inputStream.read(buffer)) > 0){
                        outputStream.write(buffer, 0, len);
                    }

                    if (listener != null){
                        G.HANDLER.post(new Runnable() {
                            @Override
                            public void run() {
                                listener.onDownloadComplete(downloadPath, filepath);
                            }
                        });
                    }
                    outputStream.close();

                } catch (MalformedURLException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        });
        thread.start();
    }
}