PeterL PeterL - 7 days ago 6
Android Question

"ArrayAdapter requires the resource ID to be a TextView" xml problems

I am getting an error when trying to set my view to display the

ListView
for the file I want to display(text file). I am pretty sure it has something to do with the xml. I just want to display the information from
this.file = fileop.ReadFileAsList("Installed_packages.txt");
. My code:

public class Main extends Activity {
private TextView tv;
private FileOperations fileop;
private String[] file;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.fileop = new FileOperations();
this.file = fileop.ReadFileAsList("Installed_packages.txt");
setContentView(R.layout.main);
tv = (TextView) findViewById(R.id.TextView01);
ListView lv = new ListView(this);
lv.setTextFilterEnabled(true);
lv.setAdapter(new ArrayAdapter<String>(this, R.layout.list_item, this.file));
lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {

public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
// When clicked, show a toast with the TextView text
Toast.makeText(getApplicationContext(), ((TextView) view).getText(), Toast.LENGTH_SHORT).show();
}
});
setContentView(lv);
}

}


list_item.xml :

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
android:padding="10dp"
android:textSize="16sp"
android:textColor="#000">

</LinearLayout>


main.xml :

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:weightSum="1">
<ScrollView
android:id="@+id/SCROLLER_ID"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:scrollbars="vertical"
android:fillViewport="true">
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:padding="5sp"
android:id="@+id/TextView01"
android:text="@string/hello"/>
</ScrollView>

</LinearLayout>

Answer

The ArrayAdapter requires the resource ID to be a TextView XML exception means you don't supply what the ArrayAdapter expects. When you use this constructor:

new ArrayAdapter<String>(this, R.layout.a_layout_file, this.file)

R.Layout.a_layout_file must be the id of a xml layout file containing only a TextView(the TextView can't be wrapped by another layout, like a LinearLayout, RelativeLayout etc!), something like this:

<?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="wrap_content" 
    // other attributes of the TextView
/>

If you want your list row layout to be something a little different then a simple TextView widget use this constructor:

new ArrayAdapter<String>(this, R.layout.a_layout_file, 
   R.id.the_id_of_a_textview_from_the_layout, this.file)

where you supply the id of a layout that can contain various views, but also must contain a TextView with and id(the third parameter) that you pass to your ArrayAdapter so it can know where to put the Strings in the row layout.