How to properly implement a custom list with images using the Picasso library?

I have created a custom list layout with images downloaded from the web, for example:

http://i.stack.imgur.com/l8ZOc.png

It works fine when scrolling down. However, when scrolling down, the previous items exit the screen and then are destroyed. When you try to scroll the page again, it loads again (from the cache, faster but not instantaneously) which causes a delay and is not as fluent as it should be.

1. Is there an example of how to do this correctly?
2.Is there a way to prevent the list items from being destroyed when they are off screen?
3.If so, would it cause problems with saving too many items?

Below is my code:

MenuAdapter:

public class MenuAdapter extends BaseAdapter{

    Context context;
    List<MyMenuItem> menuItems;

    MenuAdapter(Context context, List<MyMenuItem> menuItems) {
        this.context = context;
        this.menuItems = menuItems;
    }

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

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

    @Override
    public long getItemId(int position) {
        return menuItems.indexOf(getItem(position));
    }

    private class ViewHolder {
        ImageView ivMenu;
        TextView tvMenuHeader;
    }



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

        ViewHolder holder = null;

        LayoutInflater mInflater = (LayoutInflater) context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
        if (convertView == null) {
            convertView = mInflater.inflate(R.layout.menu_item, null);
            holder = new ViewHolder();

            holder.tvMenuHeader = (TextView) convertView.findViewById(R.id.tvMenuHeader);
            holder.ivMenu = (ImageView) convertView.findViewById(R.id.ivMenuItem);

            convertView.setTag(holder);
        } else {
            holder = (ViewHolder) convertView.getTag();
        }

        MyMenuItem row_pos = menuItems.get(position);

        Picasso.with(context)
                .load(row_pos.getItem_image_url())
                .into(holder.ivMenu);

        holder.tvMenuHeader.setText(row_pos.getItem_header());

        Log.e("Test", "headers:" + row_pos.getItem_header());
        return convertView;
    }

}

      

        
        
        
      

    

MyMenuItem:

public class MyMenuItem {

    private String item_header;
    private String item_image_url;

    public MyMenuItem(String item_header, String item_image_url){
        this.item_header=item_header;
        this.item_image_url=item_image_url;
    }

    public String getItem_header(){
        return item_header;
    }

    public void setItem_header(String item_header){
        this.item_header=item_header;
    }

    public String getItem_image_url(){
        return item_image_url;
    }

    public void setItem_image_url(String item_image_url){
        this.item_image_url=item_image_url;
    }
}

      

        
        
        
      

    

MainActivity:

public class MyActivity extends Activity implements AdapterView.OnItemClickListener {

    List<MyMenuItem> menuItems;
    ListView myListView;
    JSONArray jsonArray;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my);
        Bundle extras = getIntent().getExtras();

        if(extras!=null){
            try{
                jsonArray = new JSONArray(extras.getString("Data"));
            }catch (Exception e){
                e.printStackTrace();
            }
        }


        menuItems = new ArrayList<MyMenuItem>();


        for (int i = 0; i < jsonArray.length(); i++) {
            try {
                MyMenuItem item = new MyMenuItem(jsonArray.getJSONObject(i).getString("title"), jsonArray.getJSONObject(i).getString("imageURL"));
                menuItems.add(item);
            }catch (Exception e){
                e.printStackTrace();
            }

        }

        myListView = (ListView) findViewById(R.id.list);
        MenuAdapter adapter = new MenuAdapter(this, menuItems);
        myListView.setAdapter(adapter);
        myListView.setOnItemClickListener(this);
    }
}

      

        
        
        
      

    

MenuItem.xml:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">


    <ImageView
        android:id="@+id/ivMenuItem"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:scaleType="center"
        android:src="@drawable/em" />

    <TextView
        android:id="@+id/tvMenuHeader"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#55000000"
        android:paddingBottom="15dp"
        android:paddingLeft="10dp"
        android:paddingRight="10dp"
        android:paddingTop="15dp"
        android:textColor="@android:color/white"
        android:layout_gravity="left|top"
        android:layout_alignBottom="@+id/ivMenuItem"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true" />
</RelativeLayout>