Use a List<type> instead of ArrayList<Hashmap<String,String>> for list view

Question

I have an object:

private ArrayList<HashMap<String, String>> customerDataList;

Which I populate with data retrieved from a web service call. The below is inside a loop iterating over the retrieved json data:

HashMap<String, String> customer = new HashMap<>();
//snip
customer.put("CustomerName", customerName);
//snip
customerDataList.add(customer);
//rinse and repeat

Then I display this in a list view in my activity with:

ListAdapter adapter = new SimpleAdapter(Activity.this, customerDataList,
                R.layout.list_item, new String[] {"CustomerName"}, new int[] { R.id.customerName });
setListAdapter(adapter);

However I am wondering if there is a way I can use a List instead.

I created my customer class, created a List of it like so:

private List<Customer> customerList;

However when it comes to setting the ListAdapter I am unsure of what to put. I replaced customerDataList with customerList but I receive errors.

Edit: The error is

SimpleAdapter() in SimpleAdapter cannot be applied to:
Expected data: java.util.Map<java.lang.String.?>>
Actual arguments: customerList <Customer>

Edit: my class structure

private class Customer
{
    private int customerID;
    private String customerName;
    private String customerLocation;
    private String runningTime;
    private double distance;
}

What error? Can you post error or stack trace

atish shimpi
– atish shimpi

2015-01-10 19:09:22 +00:00
Commented Jan 10, 2015 at 19:09 — atish shimpi
– atish shimpi, Commented Jan 10, 2015 at 19:09
Have you tried creating a custom adapter?

Kuba Spatny
– Kuba Spatny

2015-01-10 19:16:26 +00:00
Commented Jan 10, 2015 at 19:16 — Kuba Spatny
– Kuba Spatny, Commented Jan 10, 2015 at 19:16

Simas · Accepted Answer · 2015-01-10 19:45:40Z

1

If you want a use a list of custom objects you need to use another adapter e.g. ArrayAdapter:

List<Customer> customerList = null;
ArrayAdapter<Customer> customerAdapter = new ArrayAdapter<Customer>(this,
        R.layout.list_item, customerList);

Now since ArrayAdapter expects strings to come out of your custom objects, override a toString method in your class:

class Customer {
    String customerName;

    @Override
    public String toString() {
        return customerName;
    }
}

If your customer class has multiple fields that will need to be used in your adapter, you will need a custom adapter, something like this:

// Turns out that when the layout is not a TextView, you need to provide the id
// of the TextView the adapter can bind to
ArrayAdapter<Customer> customerAdapter = new ArrayAdapter<Customer>(this,
        R.layout.list_item, R.id.customer_name, customerList) {
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View view = super.getView(position, convertView, parent);

        TextView name = view.findViewById(R.id.customer_name);
        TextView surname = view.findViewById(R.id.customer_surname);

        name.setText(getItem(position).customerName);
        surname.setText(getItem(position).customerSurname);

        return view;
    }
};

You can google to find some performance adjustments for custom adapters.

edited Jan 10, 2015 at 19:45

answered Jan 10, 2015 at 19:22

Simas

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6 Comments

andrewb Over a year ago

The View view = super.getView(...) generates an error when I run. /ArrayAdapter﹕ You must supply a resource ID for a TextView

Simas Over a year ago

@andrewb I updated my answer. However you should have provided important details (like your customer class structure and the fields that the adapter will use) in your question.

andrewb Over a year ago

Thanks for your help. So how do I add more fields, such as R.id.customer_name, R.id.customerAddress? I added customer address and it complains about the constructor

Simas Over a year ago

@andrewb to add more fields, modify the getView method, not the constructor. In my example there are 2 fields, you can add as many as you like as long as they're found in the list_item.xml and exist in your Customer class.

andrewb Over a year ago

Thanks, so that works, but I do not understand why R.id.customer_name is in the ArrayAdapter constructor but not the other fields? For example if I bound 5 fields that is the only field in ctor

|

Sanjeet A · Accepted Answer · 2015-01-10 19:24:27Z

0

You can use

List<Customer>

but you need to go for a custom adapter instead of Simple adapter.

The data containing the customer object need to be set, the simple adapter can only accept the name value pare map. So you need to extend the adapter/Basadpter class the requirement.

edited Jan 10, 2015 at 19:24

answered Jan 10, 2015 at 19:12

Sanjeet A

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1 Comment

andrewb Over a year ago

And how does one do that?

Kuba Spatny · Accepted Answer · 2015-01-10 19:24:32Z

The easiest way is to assign the values from Customer object to views in your list row layout is to create a custom Adapter extending the ArrayAdapter class:

public class CustomAdapter extends ArrayAdapter<Customer> {

private final Context context;
  private final Customer[] values;

  public MySimpleArrayAdapter(Context context, Customer[] values) {
    super(context, R.layout.rowlayout, values);
    this.context = context;
    this.values = values;
  }

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

    if(convertView == null {
       LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
       convertView = inflater.inflate(R.layout.listviewrowlayout, parent, false);
    }

    TextView customerName= (TextView) convertView.findViewById(R.id.customerName);
    TextView customerAge= (TextView) convertView.findViewById(R.id.customerAge);

    customerName.setText(values[position].getName());
    customerAge.setText(values[position].getAge());

    return convertView;
  }
}

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