Android. Using HashMap for listView

Question

I try to use HashMap<String, String>() to populate ListView. I'm supposed to fetch my site API to get the latest news json representation. By now I basically try to simulate dynamic data and put the news manually. The problem I faced is that it won't add news as expected but just repeats them. Sorry for bad explanation. Here's my code to clarify

public class MainActivity extends Activity {

public final static String EXTRA_MESSAGE = "ru.rateksib.sendmessage.MESSAGE";

EditText editText;
ListView newsList;
Map<String, String> map;
ArrayList<HashMap<String, String>> NewsArrayList;
NewsArrayAdapter arrayAdapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);


    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    LayoutInflater inflater = this.getLayoutInflater();
    View convertView = (View) inflater.inflate(R.layout.news_dialog, null);
    builder.setView(convertView);
    builder.setTitle("Новости компании");

    // set up list view inside alertDialog
    newsList = (ListView) convertView.findViewById(R.id.dialogNewsList);

    // map
    NewsArrayList = new ArrayList<HashMap<String, String>>();
    map = new HashMap<String, String>();


    map.put("title", "New branch opened!");
    map.put("date", "28.03.2014");
    NewsArrayList.add((HashMap<String, String>) map);   

    map.put("title", "Second one!");
    map.put("date", "28.03.2014");
    NewsArrayList.add((HashMap<String, String>) map);


    // custom adapter
    arrayAdapter = new NewsArrayAdapter(NewsArrayList, this);
    newsList.setAdapter(arrayAdapter);

So when I run the app the list is populated twice with the last set of title and date.

My custom adapter code is

 public class NewsArrayAdapter extends BaseAdapter {

    ArrayList<HashMap<String,String>> names;
    Context ctxt;
    LayoutInflater inflater;

    public NewsArrayAdapter(ArrayList<HashMap<String,String>> newsArrayList, Context c) {
        names = newsArrayList;
        ctxt = c;
        inflater = (LayoutInflater)c.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    @Override
    public int getCount() {
        // TODO Auto-generated method stub
        return names.size();
    }

    @Override
    public Object getItem(int arg0) {
        // TODO Auto-generated method stub
        return names.get(arg0);
    }

    @Override
    public long getItemId(int arg0) {
        // TODO Auto-generated method stub
        return arg0;
    }

    @Override
    public View getView(int position, View view, ViewGroup viewGroup) {
        // TODO Create the cell (View) and populate it with an element of the array
        if (view == null) {
//          view = inflater.inflate(android.R.layout.simple_list_item_1, viewGroup, false);
            view = inflater.inflate(R.layout.dialog_news_list_item, viewGroup, false);
        }

        TextView title = (TextView) view.findViewById(R.id.title);
        TextView date = (TextView) view.findViewById(R.id.date);
        title.setText(names.get(position).get("title"));
        date.setText(names.get(position).get("date"));
        return view;
    }

}

Christopher Tan · Accepted Answer · 2017-01-03 14:47:10Z

1

I know this is old post, but I know what the question is asking ask he request for a loop, just put your hashMap into the loop as well and you will be fine. for your loop n count, count on your variables

 for(int i = 0; i< n; i++){
                HashMap<String, String> hashMap = new HashMap<>();
                map.put("title", $title);
                map.put("date", $date);

                classList.add(hashMap);
            }

answered Jan 3, 2017 at 14:47

Christopher Tan

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Comments

Thomas Bouron · Accepted Answer · 2014-03-28 10:17:47Z

0

It's because you add two times map which is a reference to the same object. After your first NewsArrayList.add((HashMap<String, String>) map);, you overwrite the values of title and date, that's why you end up with the same values twice.

To fix, just create another map like this:

// map
NewsArrayList = new ArrayList<HashMap<String, String>>();

map1 = new HashMap<String, String>();
map1 .put("title", "New branch opened!");
map1 .put("date", "28.03.2014");
NewsArrayList.add((HashMap<String, String>) map1);   

map2 = new HashMap<String, String>();
map2.put("title", "Second one!");
map2.put("date", "28.03.2014");
NewsArrayList.add((HashMap<String, String>) map2);

answered Mar 28, 2014 at 10:17

Thomas Bouron

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2 Comments

Almazik G Over a year ago

thanks for your answer but i'm supposed to do this in the loop. How can I go about it?

Thomas Bouron Over a year ago

What do you mean in a loop? I just got your code you posted as an example. The point is, each map object you want to add to the list must be a new object. Don't reuse the same map.

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