Android Listview showing duplicate entries

Question

I tried to display values from json array in listview. But it's displaying the duplicate entries in all the listview buttons. Here is my code

MenuFragment:

  JSONObject json = jParser.makeHttpRequest(CommonUtilities.SERVERURL_GET_MENUS, "GET", params);
          SUCCESS = json.getString(TAG_SUCCESS);
          if (SUCCESS.equalsIgnoreCase("false")) {
              JSONArray jsonarrays = json.getJSONArray("sub_menus");
              HashMap<String, String> sb = new HashMap<String, String>();
              for (int k = 0; k < jsonarrays.length(); k++) {
                   JSONObject main_menus = jsonarrays.getJSONObject(k);
                   SUB_MENU_ID = main_menus.getString("sub_menu_id");
                   SUB_MENU_NAME = main_menus.getString("sub_menu_name");
                   sb.put(SUB_MENU_ID, SUB_MENU_NAME);
                   submenus.add(sb);
                } }

  protected void onPostExecute(String result) {
      try {
         submenuadapter=new SubmenuCategoryAdapter(submenus,getActivity());
         sb_list.setAdapter(submenuadapter);
      }

SubmenuCategoryAdapter:

Adapter contains button to display the list values.

public class SubmenuCategoryAdapter extends BaseAdapter {
    ArrayList<HashMap<String, String>> mainmenu;
    HashMap<String, String> mainmenumap = new HashMap<String, String>();
    Context con;
    public SubmenuCategoryAdapter(ArrayList<HashMap<String, String>> mainmenu, Context con) {
        super();
        this.mainmenu = mainmenu;
        this.con = con;
    }
    @Override
    public int getCount() {
        return mainmenu.size();
    }
    @Override
    public Object getItem(int position) {
        return position;
    }
    @Override
    public long getItemId(int position) {
        return position;
    }
    @SuppressLint("ViewHolder")
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        final Holder holder = new Holder();
        LayoutInflater layoutInflater = (LayoutInflater) con.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        mainmenumap = mainmenu.get(position);
        View submenuview = layoutInflater.inflate(R.layout.submenu_button, null);
        holder.submenu_btn=(Button)submenuview.findViewById(R.id.submenu_layout_button);
        String btn_name=mainmenu.get(position).toString();
        holder.submenu_btn.setText(btn_name);
        return submenuview;
    }
    public class Holder {
      Button submenu_btn;
    }
}

Answer 1

Change your getView method to following

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    Holder viewHolder;      
    if(convertView == null){
        convertView = LayoutInflater.from(parent.getContext())
                                  .inflate(R.layout.submenu_button, parent, false);
        viewHolder = new Holder();
        viewHolder.submenu_btn = (Button) convertView
                                      .findViewById(R.id.submenu_layout_button);
        convertView.setTag(viewHolder);
    } else {
        viewHolder = (Holder) convertView.getTag();
    }

    String btn_name=mainmenu.get(position).toString();
    viewHolder.submenu_btn.setText(btn_name);
    return convertView;
}

UPDATE

To answer your second question in the comments, I am not sure why are you using ArrayList of HashMaps. Why not use plain java object? I am showing below how I would do it with POJO (Plain Old Java Object)

Create a POJO describing your menu item

public class MenuItem {
    public int MenuId;
    public String MenuName;
}

MenuFragment

//initialize submenus
List<MenuItem> submenus = new ArrayList<>();

JSONArray jsonarrays = json.getJSONArray("sub_menus");
for (int k = 0; k < jsonarrays.length(); k++) {
    JSONObject main_menus = jsonarrays.getJSONObject(k);
    MenuItem item = new MenuItem();
    item.MenuId = main_menus.getInt("sub_menu_id");
    item.MenuName = main_menus.getString("sub_menu_name");
    submenus.add(item);
} 

//initializing adapter
submenuadapter = new SubmenuCategoryAdapter(submenus, getActivity());
sb_list.setAdapter(submenuadapter);

Adapter class

public class SubmenuCategoryAdapter extends BaseAdapter {
    List<MenuItem> mainmenu;
    Context con;
    public SubmenuCategoryAdapter(List<MenuItem> mainmenu, Context con) {
        super();
        this.mainmenu = mainmenu;
        this.con = con;
    }

    ....

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        Holder viewHolder;      
        if(convertView == null){
            convertView = LayoutInflater.from(parent.getContext())
                                  .inflate(R.layout.submenu_button, parent, false);
            viewHolder = new Holder();
            viewHolder.submenu_btn = (Button) convertView
                                      .findViewById(R.id.submenu_layout_button);
            convertView.setTag(viewHolder);
        } else {
            viewHolder = (Holder) convertView.getTag();
        }

        String btn_name = mainmenu.get(position).MenuName;
        viewHolder.submenu_btn.setText(btn_name);
        return convertView;
    }

}