Creating ListView programmatically

Question

Android beginner here. I was playing around with ListViews, trying to create them dynamically instead of the XML file. I observe the following odd behavior in my code.

public class SettingsHolder extends Activity {

@Override
public void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    LinearLayout ll = new LinearLayout(this);
    ListView lv = new ListView(this);
    String[] values = new String[10];
    for(int i=0;i<10;i++){
        values[i] = ""+i;
    }
    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.layout.list_item, values);
    lv.setAdapter(adapter);
    lv.setOnItemClickListener(new OnItemClickListener(){

        @Override
        public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
                long arg3) {
            //Toast.makeText(getBaseContext(), ""+arg2,     Toast.LENGTH_SHORT).show();
            Log.d("DEBUG", ""+arg2);

        }

    });

    ll.addView(lv);
    setContentView(ll);

}


}

Basically I first create a LinearLayout object and then make a ListView object as one of its child. I observed that the list items so created are not clickable. But if I write

setContentView(lv);

instead of

setContentView(ll);

the list items are clickable. Can anyone please explain this? How do I make the list items clickable if I have to implement my class the latter way? I don't want to go the ListActivity way.

list_item.xml

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:padding="10dp"
    android:textSize="16sp" >
</TextView>

Your code looks fine, I even compiled to be sure, but the OnItemClickListener executes as promised... — Sam
– Sam, Commented Jun 12, 2012 at 1:42
What happens if you set the content view and then add the listvieww? — Barak
– Barak, Commented Jun 12, 2012 at 2:58
Nope, still doesn't work. The list displays fine but the list items are un-clickable. — VJune
– VJune, Commented Jun 12, 2012 at 3:35

Ruobin Wang · Accepted Answer · 2012-06-13 01:21:54Z

6

change your code:

ll.addView(lv);

to this:

ll.addView(lv, LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT);

Problem solved, I guess, you have to give the listview some kind of layout restriction or definition, so it can work properly.

edited Jun 13, 2012 at 1:21

answered Jun 12, 2012 at 7:52

Ruobin Wang

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4 Comments

VJune Over a year ago

hmm... it works but making the width and the height of the child View equal to -1 is a bit odd. Don't you think?

Ruobin Wang Over a year ago

Why odd? -1 means View.FILL_PARENT, I think it is reasonable. Sorry, maybe I didn't make it clear, you can write like this: ll.addView(lv, View.FILL_PARENT, View.FILL_PARENT);

VJune Over a year ago

Small correction, I think it should be LayoutParams.FILL_PARENT instead of View.FILL_PARENT.

Ruobin Wang Over a year ago

yep, you're right, I have corrected my answer, to avoid some misleading.

Swifty McSwifterton · Accepted Answer · 2012-06-12 05:27:28Z

2

I was able to get this to work, but I had to create the LinearLayout in XML, which I realize is different than how you have it. However, given that either way the LinearLayout is the root element, and given that you are still creating the ListView programmatically, it really should make no difference IMHO.

public class ExampleActivity extends Activity implements OnItemClickListener {

private LinearLayout ll;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.your_layout);
    ll = (LinearLayout) findViewById(R.id.main_ll);
    ListView lv = new ListView(this);
    ll.addView(lv);

    String[] values = new String[10];
    for (int i = 0; i < 10; i++) {
        values[i] = "" + i;
    }

    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
            android.R.layout.simple_list_item_1, values);
    lv.setAdapter(adapter);
    lv.setOnItemClickListener(this);
}

@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
    Toast.makeText(this, "" + arg2, Toast.LENGTH_SHORT).show();
    Log.d("DEBUG", "" + arg2);
}

}

answered Jun 12, 2012 at 5:27

Swifty McSwifterton

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1 Comment

VJune Over a year ago

My question was intended more towards understanding the behavior of my program. I guessed alternate implementations would definitely exist. But thanks for your reply.

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