What adapter shall I use to use HashMap in a ListView

android

I want to use HashMap for a list of items of Adapter for a ListView. I was going to use ArrayAdapter<> but I can't because it is working with List<> only. What adapter shall I use?

There are no predefined Adapters which will render a HashMap. I suggest creating your own Adapter by extending BaseAdapter.

Edit: It is posible to use HashMap with and extended BaseAdapter, here's an(untested) example:

public class HashMapAdapter extends BaseAdapter {

    private HashMap<String, String> mData = new HashMap<String, String>();
    private String[] mKeys;
    public HashMapAdapter(HashMap<String, String> data){
        mData  = data;
        mKeys = mData.keySet().toArray(new String[data.size()]);
    }

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

    @Override
    public Object getItem(int position) {
        return mData.get(mKeys[position]);
    }

    @Override
    public long getItemId(int arg0) {
        return arg0;
    }

    @Override
    public View getView(int pos, View convertView, ViewGroup parent) {
        String key = mKeys[pos];
        String Value = getItem(pos).toString();

        //do your view stuff here

        return convertView;
    }
}

This comes with the following caveat, the order of the items is not guaranteed to be the same order you added them. Writing this example has made me realize; Don't use HashMap in an adapter :)

Thanks for the answer longhairedsi

This comes with the following caveat, the order of the items is not guaranteed to be the same order you added them. Writing this example has made me realize; Don't use HashMap in an adapter :)

To get around this problem, use a LinkedHashMap instead.

public class HashMapAdapter extends BaseAdapter {
    private LinkedHashMap<String, String> mData = new LinkedHashMap<String, String>();
    private String[] mKeys;
    public HashMapAdapter(LinkedHashMap<String, String> data){
        mData  = data;
        mKeys = mData.keySet().toArray(new String[data.size()]);
    }

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

    @Override
    public Object getItem(int position) {
        return mData.get(mKeys[position]);
    }

    @Override
    public long getItemId(int arg0) {
        return arg0;
    }

    @Override
    public View getView(int pos, View convertView, ViewGroup parent) {
        String key = mKeys[pos];
        String Value = getItem(pos).toString();

        //do your view stuff here

        return convertView;
    }
}

You can get an array of your map entries:

Entry<MyKey, MyValue>[] entries =
    map.entrySet().toArray(new Entry<MyKey, MyValue>[0]);

That being said, if you are planning on updating your map or using map features in the adapter then making a custom adapter is not difficult and would make much more sense.

You can start out by subclassing BaseAdapter, which provides implementations for all but a few of the Adapter methods you need to get running.

What adapter shall I use to use HashMap in a ListView

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