Get info of item clicked in ListActivity?

Question

I'm building a ListActivity with a list of activities (each item on the list is an activity of my app). When one of the items in the list is clicked I want to get it's info. It's mostly done, however I'm getting an error when trying to retrieve the item data onclick.

This is what I'm doing:

private class ActivityItem {
    private CharSequence title;
    private Class activityClass; // I didn't limit it to Activities because I might use it for Fragments

    public ActivityItem(int titleResId, Class activityClass) {
        this.title = getResources().getString(titleResId);
        this.activityClass = activityClass;
    }

    @Override
    public String toString() {
        return title.toString();
    }
}

private static ActivityItem[] mItems;

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_items_not_added);

    // Instantiate the list of samples.
    ActivityItem[] mItems = new ActivityItem[]{
            new ActivityItem(R.string.dialer, Example1.class),
            new ActivityItem(R.string.clock, Example2.class),
    };

    setListAdapter(new ArrayAdapter<ActivityItem>(this, android.R.layout.simple_list_item_1, android.R.id.text1, mItems));
}

@Override
protected void onListItemClick(ListView listView, View view, int position, long id) {
    Log.d("Title:", mItems[position].toString()); // This returns error
}

Log:

03-15 17:45:30.302  18134-18134/com.example.android.launcher E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.example.android.launcher, PID: 18134
    java.lang.NullPointerException
            at com.example.android.launcher.ItemsNotAdded.onListItemClick(ItemsNotAdded.java:92)

What am I doing wrong?

Answer 1

Item is additionally, locally declared in onCreate() - you can't access this instance. Just use

mItems = new ActivityItem[]{
        new ActivityItem(R.string.dialer, Dialer.class),
        new ActivityItem(R.string.clock, Clock.class),
        new ActivityItem(R.string.flashlight, Flashlight.class),
        new ActivityItem(R.string.contact_list, ContactList.class),
};

in onCreate() and the static ActivityItem[] mItems will be assigned instead. Otherwise it will be null .

ps as I see you use an ListActivity . In this case you could call getListView().getAdapter() getItem(int position) in onListItemClick as well. So no static member is required. Check ListActivities API.