android Listview not showing anything

Question

I am working on a first basic android app as a university project and I have an array list of names. I want it to be put into a ListView. The problem I have is nothing appears when I bring in the ListViewunder the xml document. I don't get the basic template for item1, sub item 1 etc. Then when I set up the array to play in the list view still empty list. Below I have the xml document

<RelativeLayout
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <ListView
        android:layout_width="wrap_content"
        android:layout_height="277dp"
        android:id="@+id/listView" android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true" android:layout_marginTop="7dp"
        android:layout_alignParentBottom="true"/>
</RelativeLayout>

then here is the java code:

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    populateListView();
}

private void populateListView() {
    String[] myItems = {"frank","george","alice", "anna"};
    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.layout.main, myItems);
    ListView list = (ListView)findViewById(R.id.listView);
    list.setAdapter(adapter);
}

Solution 1

Your problem is that you have the same layout R.layout.main for two different use.
You set the content view as setContentView(R.layout.main); where your ListView is but you also use this layout with your adapter as new ArrayAdapter<String>(this, R.layout.main, myItems);.
So with your code, you don't have any item layout to display your array myItems. You need to create another layout as R.layout.item_layout with a TextView inside (or use an android layout like android.R.layout.simple_list_item_1) for your adapter.

Note: to avoid some bugs with ListView, you have also to set the height to match_parent or fill_parent

Solution 2

Try this for your adapter:

ArrayAdapter<String> adapter= 
new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, myItems);

The adapter has to inflate a TextView. You can make your own TextView (if you want to customize it) in XML.

Then it will be:

ArrayAdapter<String> adapter= 
new ArrayAdapter<String>(this, R.layout.yourcustomtextview, myItems);