Can't get custom ListAdapter to work

Question

I have followed various "how to" examples to the letter (or so I thought), but I still can't get my custom ListAdapter to work. I have a dialog with a list view containing strings which are references to an array of objects (of class "Notam"). I want to set the colour of each list item according to an attribute of the referenced object.

(Before you read my code, I have a quirk that the braces must line up or I can't see where the blocks are. I don't like the convention of putting an opening brace at the end of the same line.)

This is the code for the custom class (just as a test I am trying to set the text colour of each item to magenta):

private class GotoAdapter extends ArrayAdapter<String>
{
    private ArrayList<String> items;

    public GotoAdapter(Context context, int textViewResourceId, ArrayList<String> items)
    {
        super(context, textViewResourceId, items);
        this.items = items;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent)
    {
        View v = convertView;
        if (v == null)
        {
            LayoutInflater vi = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            v = vi.inflate(R.layout.goto_row, null);
        }
        String s = items.get(position);
        if (s != null)
        {
            TextView tt = (TextView) v.findViewById(R.id.text1);
            if (tt != null)
            {
                String s1 = (String)tt.getText(); // this is always an empty string!
                tt.setTextColor(0xFF00FF); // this has no effect!
            }
        }
        return v;
    }
}

String s has the displayed text as expected (except you can't see it on the screen) when using this derived class), but the text in the returned TextView is always an empty string, and setting the colour has no effect.

This is the code that displays the dialog when a "Goto" button is clicked in my main view:

mGotoButton.setOnClickListener(new View.OnClickListener()
{
    public void onClick(View v)
    {
        // The pre-loaded array gets round a problem which I read about somewhere else
        // (the ArrayList gets cleared again below)
        String[]    array = {"one", "two", "three"};
        ArrayList<String> lst = new ArrayList<String>();
        lst.addAll(Arrays.asList(array));

        // custom dialog
        final Dialog dialog = new Dialog(context);

        dialog.setContentView(R.layout.goto_dialog);
        dialog.setTitle("Choose Notam");

        // Create the list view and adapter
        final ListView list = (ListView) dialog.findViewById(R.id.goto_list);

        // If I replace this reference to my custom adapter...
        final GotoAdapter adapter = new GotoAdapter
                (mContext, R.layout.goto_row, lst);

        // ... with this normal one, everything works!
        // (but of course now I can't get access to the objects.)
//      final ArrayAdapter<String> adapter = new ArrayAdapter<String>
//              (mContext, R.layout.goto_row, lst);

        list.setAdapter(adapter);

        // Populate the adapter
        adapter.clear();        // first clear the silly preset strings

        // Notam is my object class.
        // Spine.mNotamsDisplayed is a public static NotamArray.
        // class NotamArray extends ArrayList<Notam>
        // Spine is my main activity where I keep my global (app-wide) stuff.

        for (Notam notam : Spine.mNotamsDisplayed)
        {
            // This gets the reference string from the Notam object.
            // This is what goes into the list.
            String s = notam.getReference();
            adapter.add(s);
        }

        // Sort into alphabetical order
        adapter.sort(new Comparator<String>()
        {
            public int compare(String arg0, String arg1)
            {
                return arg0.compareTo(arg1);
            }
        });

        list.setOnItemClickListener(new AdapterView.OnItemClickListener()
        {
            public void onItemClick(AdapterView<?> a, View v, int pos, long id)
            {
                String  s;
                int     i;

                s = (String)a.getItemAtPosition(pos);

                // This static function returns the index in Spine.mNotamsDisplayed
                // which is referenced by the reference string s.
                // I have to do this because I lost the one-for-one correlation of page
                // indexes with list view entries when I did the sort.
                i = NotamArray.findNotamIndexByReference(Spine.mNotamsDisplayed, s);
                if (i >= 0)
                {
                    // This is what the Goto button and dialog is all about: this
                    // just moves my main view's pager to the page that was selected.
                    mPager.setCurrentItem(i);
                }
                dialog.dismiss();
            }
        });

        dialog.show();
    }
});

This is my xml for the dialog (goto_dialog.xml):

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

    <ListView 
        android:id="@+id/goto_list"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" />
</RelativeLayout>    

And this is my xml for the list view row (goto_row.xml):

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/text1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:textColor="#00FF00"
    android:gravity="center_vertical"
     android:textAppearance="?android:attr/textAppearanceMedium"
    android:padding="2dp" 
    android:textSize="20dp"
/>

(I set the text colour to green so I could see that this bit was working if I used the standard list view adapter. (Sure enough the text of every entry was green. However no text could be seen if I used my custom adapter, although it was there - I assume black on black.)

There must be someone out there who can spot what must be a trivial error I have made - please!

Answer 1

I found the trivial error that I hinted at at the end of my question. It was this line in the custom adapter:

tt.setTextColor(0xFF00FF);

It seems that 0xFF00FF is not a valid colour value, which is why I saw nothing on the screen. Changing that to:

tt.setTextColor(Color.rgb(255, 0, 255);

fixes the problem, and the default green colour is changed to magenta, and I can set the text to the value I want. So I can now set the individual row colours to what they need to be.

Thanks to @LukasKnuth and @tigerpenguin for pointing me in the right direction.

Answer 2

From what I read, it seems like you want to set the text color of every list item to match the color you have in your array.

I want to set the colour of each list item according to an attribute of the referenced object.

However, your initial array is set as

String[] array = {"one", "two", "three"};

So this will lead to problems later when you are dynamically setting the text color based on your array. But I'm sure you meant to change that later.

When you use a standard array adapter, it just shows the items in the array as a text, that's why:

if I used the standard list view adapter. (Sure enough the text of every entry was green. However no text could be seen if I used my custom adapter

To see if your custom adapter is working (changing color), you can just start off by adding one line to your TextView of goto_row.xml file:

android:text="Test String"

Now it will show "Test String" with different colors, and the

String s1 = (String)tt.getText();

above line will get "Test String"