Question

I have created a listview that sits inside a larger activity (the list view fills half the screen, with inputs/buttons above it). This listview uses a custom adapter to draw the row views.

Inside the row view is a button, which when clicked/tapped i want the activity to handle, and not the adapter. However i don’t know how inside the adapter class, i can tell it to use the activity. Since it’s OOP, im assuming i have to pass some sort of reference to the activity when setting up the adapter (rather than hardcoding the parent activity into the adapter).

I had a simlier issue with sharing a dataset between the activity and adapter (i wanted the adapter to use an arraylist from the activity), however i couldn’t solve that one either so i ended up passing the arraylist through as a duplicate into the adapter. So i would hope working out the click listener, will also mean i can get rid of that duplicate data having to be created?

All the code is pretty simple, but here’s a rough outline:

Setting the list adapter & declaring dataset (this is the activity dataset, not the adapter)

numbersListAdapter = new NumberListAdapter(this);
numbersList.setAdapter(numbersListAdapter);
this.selectedContacts = new HashMap<Long, HashMap<String, String>>();

Adding entry into activity data set and adding to the adapter dataset

HashMap<String, String> tempa = new HashMap<String,String>();
tempa.put("name", name);
tempa.put("number", number);
this.selectedContacts.put(contactID, tempa);

this.numbersListAdapter.addEntry(contactID, tempa);

The adapters add entry

public void addEntry(Long id, HashMap<String, String> entry) {  

        entry.put("contactID", id.toString());      

        this.selectedNumbers.add(entry);

        this.notifyDataSetChanged();

    }

The adapters constructor

public NumberListAdapter(Context context) {

        selectedNumbers = new ArrayList<HashMap<String, String>>();

        mInflater = LayoutInflater.from(context);

    }

Please note: this is my first attempt at this stuff. I’ve never done android, java and very, very little OO programming. So i already know the code is most likely inefficient and quite terrible. But i’ve got to learn somehow 🙂

EDIT

Ok so i realised ive been a little silly and i just needed to use the context passed into the adapter to reference the parent activity. However i still ain’t getting it. Heres the code:

The constructor for the adapter

numbersListAdapter = new NumberListAdapter(this);

The variable declaration and constructor method

public class NumberListAdapter extends BaseAdapter  {

    private LayoutInflater mInflater;

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

    private Context parentActivity;



    public NumberListAdapter(Context context) {

        parentActivity = (Context) context; 

        selectedNumbers = new ArrayList<HashMap<String, String>>();

        mInflater = LayoutInflater.from(context);

    }

The listener

Button theBtn = (Button)rowView.findViewById(R.id.actionRowBtn);
            theBtn.setOnClickListener(this.parentActivity);

I get two messages from eclipse, the first occurs when i comment out the listener and i get
The value of the field NumberListAdapter.parentActivity is not used

Once i add the listener in i get

The method setOnClickListener(View.OnClickListener) in the type View is not applicable for the arguments (Context)

Obviously im doing something wrong. Probably quite a silly mistake again too

Answer 1

If you need to get callback when row of the listview is clicked you can use

numbersListAdapter.setOnitemitemClickLiistener

But if you need a button inside each row to be clicked you will have to override the

getView function of your adapter and then set the onclicklistener of the button individually

Edit:
Typecast the Context to Activity

theBtn.setOnClickListener((YourActivity)this.parentActivity);