ArrayAdapter addAll function doesn't seem to be invoked

Question

My code below is for search filter for a list view. Every time the text in the tbSearch editText is changed, the items in the listview must be changed. The execution goes inside the if statement (txt.length()==0) but it does not add my array.

public void onTextChanged(CharSequence s, int start, int before, int count) {
    String txt = tbSearch.getText().toString().toLowerCase();
    aaItems.clear();
    if (txt.length() == 0)
    {
        aaItems.addAll(arrMonth);
    }
    else {
        for (String item : arrMonth) {
            if (item.toLowerCase().contains(txt)) {
                aaItems.add(item);
            }
        }
    }
}

Take a look at this answer - http://stackoverflow.com/questions/5125350/android-arrayadapter-add-method-not-working — Zain, May 19 '15 at 16:29
It seems that my arraylist gets cleared and i don't know why. I only clear my arrayadapter, not my arraylist. — Patrick De Vera, May 19 '15 at 16:40
ArrayAdapter calls notifyDataSetChanged for you on both the clear() and addAll() calls and is therefore unnecessary to call yourself. — Michael Krause, May 19 '15 at 16:41
Are you saying your arrMonth list gets cleared? Would need to see more code that interacts with it in order to determine why. :) — Michael Krause, May 19 '15 at 16:48

score 2 · Accepted Answer · edited May 19 '15 at 17:44

2

The List you are passing to your ArrayAdapter is used as the backing ArrayList for the adapter.

When you call clear(), you are literally clearing the backing array you gave it.

You'll need to ensure that the list you give the adapter is different than your arrMonth list like so:

aaItems = new ArrayAdapter(this, android.R.layout.simple_list_item_1, 
    new ArrayList<String>(arrMonths));

edited May 19 '15 at 17:44

Makoto

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answered May 19 '15 at 17:01

Michael Krause

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I tried to create a backup ArrayList but it still gets cleared out. – Patrick De Vera May 19 '15 at 17:07
So you created a final object which can't be modified. But what if my ArrayList will be coming from a database. That means i cannot use fixed lists like that. – Patrick De Vera May 19 '15 at 17:10
That's fine. Just don't use the same ArrayList to hold all the possible values as the one you pass to your ArrayAdapter. – Michael Krause May 19 '15 at 17:12
If you do nothing else - just create a new ArrayList passing it your arrMonth list as an argument when you create your ArrayAdapter and you'll see what I mean. – Michael Krause May 19 '15 at 17:13
@PatrickDeVera: I've modified my answer to suit your particular issue. You should be able to replace your line that creates the ArrayAdapter with mine and be good to go. – Michael Krause May 19 '15 at 17:22
look at my new answer @michael – Patrick De Vera May 19 '15 at 17:25

score 0 · Answer 2 · edited May 19 '15 at 17:43

Okay, I solved the problem with the help of @Michael Krause. Thanks bro! I copied another arraylist which is temp, and used in inside the textchangedlistener.

public class ItemList extends Activity {

    ListView lvItems;
    EditText tbSearch;
    //String[] arrMonth = {"January","February","March","April","May","June","July","August","September","October","November","December"};
    ArrayList<String> arrMonth = new ArrayList<>();
    ArrayList<String> temp = new ArrayList<>();
    ArrayAdapter<String> aaItems;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_item_list);
        lvItems = (ListView) findViewById(R.id.lvItems);
        tbSearch = (EditText) findViewById(R.id.tbSearch);
        PopulateArrayList();
        temp.addAll(arrMonth);

        aaItems = new ArrayAdapter(this, android.R.layout.simple_list_item_1, arrMonth);
        lvItems.setAdapter(aaItems);

        tbSearch.addTextChangedListener(new TextWatcher() {

            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {

            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                String txt = tbSearch.getText().toString().toLowerCase();
                aaItems.clear();
                if (s.length() == 0) {
                    aaItems.addAll(temp);
                } else {
                    for (String item : temp) {
                        if (item.toLowerCase().contains(txt)) {
                            aaItems.add(item);
                        }
                    }
                }
            }

            @Override
            public void afterTextChanged(Editable s) {

            }
        });

    }

    public void btnAdd_Click(View v)
    {
        aaItems.add("Patrick");
    }

    public void PopulateArrayList()
    {
        arrMonth.add("January");
        arrMonth.add("February");
        arrMonth.add("March");
        arrMonth.add("April");
        arrMonth.add("May");
        arrMonth.add("June");
        arrMonth.add("July");
        arrMonth.add("August");
        arrMonth.add("September");
        arrMonth.add("October");
        arrMonth.add("November");
        arrMonth.add("December");
    }
}

Cool, glad it worked for you Patrick. I have two requests: If my answer helped you, could you kindly accept my answer? And secondly, the moderators will probably get on you about answering your own question as opposed to modifying your original question. Just an FYI. :) — Michael Krause, May 19 '15 at 17:27
@MichaelKrause: It's perfectly fine to answer your own question. The main bit here is to see if it really did answer the question, is all. — Makoto, May 19 '15 at 17:44

ArrayAdapter addAll function doesn't seem to be invoked

2 Answers2