Setting ListView Adaptor: Null pointer exception

Question

I'm trying to set the contents of a ListView to an array of TextViews.

With what I have currently I get a Null Pointer Exception, even though I think I'd doing what is suggested here: how do I add items to listview dynamically in android

Here's what I have currently:

ListView lvSuggestions = (ListView)findViewById(R.id.lvSuggestions);

ArrayAdapter<TextView> arrayAdapter =  new ArrayAdapter<TextView>(this, android.R.layout.simple_list_item_1);
lvSuggestions.setAdapter(arrayAdapter);

But I get the exception when it sets the adaptor.

I've tried filling the ArrayList with TextViews and then creating the Adaptor with the full ArrayList, but I get the same Null Pointer Exception when I set the Adaptor.

Thanks for any help

Shankar Agarwal · Accepted Answer · 2012-04-15 15:47:54Z

1

ArrayAdapter<TextView> arrayAdapter =  new ArrayAdapter<TextView>(this, android.R.layout.simple_list_item_1);

change the above line with below

ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(context, android.R.layout.simple_list_item_1);

and add all the string that you want to display to arrayAdapter as below

arrayAdapter.add("string1");
arrayAdapter.add("string2");
arrayAdapter.add("string3");//so on

answered Apr 15, 2012 at 15:47

Shankar Agarwal

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8 Comments

Tom Bowen Over a year ago

But I don't want to fill it with Strings. Can I not fill it with TextViews?

Shankar Agarwal Over a year ago

even in textview you need to settext with strings

Tom Bowen Over a year ago

Yeah, I know I would need to set the Textview text with strings. But I want my ListView to contain an array of TextViews, because I want to be able to set the id's of the TextViews. Is it possible to fill a ListView with an ArrayList of type TextView?

Shankar Agarwal Over a year ago

but how will you settext and id to arrayadapter and what the use of setting ids to textview in your case

Tom Bowen Over a year ago

With something like the following: TextView txtArtistName = new TextView(this); txtArtistName.setId(1); txtArtistName.setText("test"); arrayAdapter.add(txtArtistName);

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Community · Accepted Answer · 2017-05-23 12:10:53Z

0

Refer this links for usage of custom adapters.

edited May 23, 2017 at 12:10

CommunityBot

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answered Apr 15, 2012 at 16:04

Shankar Agarwal

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Comments

Attila · Accepted Answer · 2012-04-15 15:45:45Z

0

This

(ListView)findViewById(R.id.lvSuggestions);

might return null if findViewById returns null (no item is found) or the returned object is not of type ListView.

Protect it with:

if (lvSuggestions != null) {
  ArrayAdapter<TextView> arrayAdapter = new ArrayAdapter<TextView>(this, 
      android.R.layout.simple_list_item_1);
  lvSuggestions.setAdapter(arrayAdapter);
}

answered Apr 15, 2012 at 15:45

Attila

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4 Comments

Tom Bowen Over a year ago

While you are right, it's not that line that is returning the exception. It's the: lvSuggestions.setAdapter(arrayAdapter);

Attila Over a year ago

yes, lvSuggestions.setAdapter() will throw a NullPointerException if lvSuggestions is null

Tom Bowen Over a year ago

Ah, I understand. But it isn't null. I can see that in Debugging.

Attila Over a year ago

Then go with Agarval's answer (I'm not knowledgable enough with the inner workings of androuid :)), but I suggest you put the protective if there anyway: can save you from future problems

Lạng Hoàng · Accepted Answer · 2013-08-24 05:33:08Z

0

Maybe you put setContentView after setAdapter.

it must be like that:

setContentView(xxx);

//....

setAdapter(xxx)

Hope it help!

answered Aug 24, 2013 at 5:33

Lạng Hoàng

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