Associating an ID with Android List View Rows

Question

I have an array of User objects. I am only showing First Name and Last Name (through toString() method that I have implemented) in a List View.

public class User
{
    public int UserID;
    public String FirstName;
    public String LastName;

     @Override public String toString() {
        StringBuilder result = new StringBuilder();
        result.append(this.FirstName + " " + this.LastName);
        return result.toString();
      }
 }

I am using the following adapter definition to bind the array of User objects to a List View.

ArrayAdapter<User> adapter = new ArrayAdapter<User>(MainActivity.this, android.R.layout.simple_list_item_1, android.R.id.text1, users);  // Users is defined as User[] users; somewhere in the code. 

listView.setAdapter(adapter);
listView.setOnItemClickListener(new OnItemClickListener () 
{
     @Override
    public void onItemClick(AdapterView<?> parent, View view,
                int position, long id) 
    {

            // Here I would like to get the UserID
    } 
});

If you need more background. My array of User objects (users) is filled through a ksoap2 Webservice call. I understand that if I was using SimpleCursorAdapter, long id in public void onItemClick(AdapterView parent, View view, int position, long id) would automatically be the id that I am interested in. But that is not the case. Any help will be appreciated very much.

Answer 1

You just need to get the User object from the list.

   public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) 
        {
             User user = (User)parent.getItemAtPosition(position);
             long userId = user.UserID;
        } 

If you want the long id to be the correct ID of the User, then you will need to override getItemId of ArrayAdapter. Ex:

ArrayAdapter<User> adapter = 
    new ArrayAdapter<User>(MainActivity.this, android.R.layout.simple_list_item_1, android.R.id.text1, users){
        @Override 
        public long getItemId(int position){
            return getItem(position).UserID;
        }
}; 

I didn't test this, but I think it should work. I also wouldn't recommend using users[position]. It is better to rely on getItem(position) in case the underlying data changes from your original User array.