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

Question

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 1

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.

Answer 2

Soution is here

listitem.xml

<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"      android:layout_width="match_parent"      android:layout_height="match_parent"      android:orientation="vertical" >       <TextView          android:id="@+id/textview"          android:layout_width="match_parent"          android:layout_height="match_parent" >      </TextView> </LinearLayout> 

Java code :

 String[] countryArray = {"India", "Pakistan", "USA", "UK"};  ArrayAdapter adapter = new ArrayAdapter<String>(this, R.layout.listitem,R.id.textview, countryArray);  ListView listView = (ListView) findViewById(R.id.listview);  listView.setAdapter(adapter);