Question

Please help me with this code – I am basically going through a book and trying to create the examples myself but I can’t get past this error. I’ve checked my LogCat and it says “java.lang.RuntimeException: Your content must have a ListView whose id attribute is ‘android.R.id.list'”. I know there is probably some small detail I’m omitting that is causing this but I can’t put my finger on it – it is almost an exact copy of a working program example given by the book. I am trying to create a simple ArrayAdapter and feed it a dummy list. Here are the three files of interest:

package com.example.bwett.SimpleList;

import android.app.ListActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;

public class SimpleList extends ListActivity {
String[] item = {"Item1", "Item2", "Item3", "Item4",
                 "Item5", "Item6", "Item7", "Item8"};
TextView mainLabel; 

@Override
public void onCreate(Bundle icicle) {
    super.onCreate(icicle);
    setContentView(R.layout.main);
    setListAdapter(new ArrayAdapter<String> (this,
                                             R.layout.row,
                                             R.id.label,
                                             item));
    mainLabel = (TextView)findViewById(R.id.mainLabel);
}
public void onListItemClick(ListView parent, View v,
                            int position, long id){
    mainLabel.setText(item[position]);
}

}

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">
<TextView
    android:id="@+id/mainLabel"   
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content"/>
<ListView
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:drawSelectorOnTop="false"/>
</LinearLayout>

ROW.XML:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="horizontal"
  android:layout_width="fill_parent"
  android:layout_height="wrap_content">
<ImageView
    android:id="@+id/ok"
    android:layout_width="22px"
    android:layout_height="fill_parent"
    android:padding="2px"
    android:src="@drawable/icon"/>

<TextView
    android:id="@+id/label"
    android:layout_width="wrap_content"
    android:layout_height="fill_parent"
    android:textSize="44sp"/>
</LinearLayout>

Answer 1

Add to the <ListView> xml element:

android:id="@android:id/list"

The error is because Android relies on you to identify the list element in your layout if you’re using ListActivity. See the ListActivity documentation for details.