Mr.Mojo Mr.Mojo - 3 months ago 15
Android Question

Android: Select first item by default in ListView in Master Detail template

I program a RSS reader with Master Detail flow with a list view on the left, and a detail view on the right.

When the screen is created the right side is empty and no item on the left is selected. How can I load the first item by default?

I found this post which is similar to my problem: Select the first item by default in a Master Detail flow

The code in my ListFragment looks like this:

@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);

// Set a listener to be invoked when the list should be refreshed.
listView = (PullToRefreshListView) getListView();

listView.setOnRefreshListener(new OnRefreshListener() {
@Override
public void onRefresh() {
//refresh list
refresh_list();
}
});

listView.setVerticalFadingEdgeEnabled(true);

// Set custom list adapter to the ListView
adapter = new CustomListAdapter(getActivity(), feed);
listView.setAdapter(adapter);

//create button, on click go to website
final Button btnAddMore = new Button(getActivity());
btnAddMore.setText(R.string.button_text_end_list);
btnAddMore.setBackgroundColor(getResources().getColor(R.color.white));
btnAddMore.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// go to website on click
String url = "http://www.test.de";
Intent web = new Intent(Intent.ACTION_VIEW, Uri.parse(url));
startActivity(web);
}
});
//add button at the end of the listview
listView.addFooterView(btnAddMore);
}

@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);

// Restore the previously serialized activated item position.
if (savedInstanceState != null
&& savedInstanceState.containsKey(STATE_ACTIVATED_POSITION)) {
setActivatedPosition(savedInstanceState
.getInt(STATE_ACTIVATED_POSITION));
}

//select the first item in the listview by default
listView.requestFocusFromTouch();
listView.setSelection(0);
listView.performItemClick(listView
.getAdapter().getView(0, view, null), 0, 0);
}

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

Log.d(TAG, "Hallo in ItemListFragment");

// show ActionBar
setHasOptionsMenu(true);

// get reference to activity
myApp = getActivity().getApplication();

// check if intent from ItemListActivity is null
Bundle be = getActivity().getIntent().getExtras();
if (be == null) {
// if null read local feed
feed = ReadFeed(fileName);
Log.d(TAG, "Lese Feed lokal :" + feed);
} else {
// else get extras from the intent
feed = (RSSFeed) getActivity().getIntent().getExtras().get("feed");
Log.d(TAG,
"Intent von ItemListActivity an ItemListFragment vorhanden");
}
}


But I receive this error:

01-19 06:39:14.723: E/AndroidRuntime(1921): Caused by: java.lang.NullPointerException
01-19 06:39:14.723: E/AndroidRuntime(1921): at ItemListFragment.onViewCreated(ItemListFragment.java:185)


in the line

listView.requestFocusFromTouch();


Please help me!

CustomListAdapter

public class CustomListAdapter extends BaseAdapter {

private LayoutInflater layoutInflater;
public ImageLoader imageLoader;
public RSSFeed _feed;
public Date pDate;

public CustomListAdapter(Activity activity, RSSFeed feed) {

_feed = feed;

layoutInflater = (LayoutInflater) activity
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
imageLoader = new ImageLoader(activity.getApplicationContext());
}

public void setNewFeed(RSSFeed feed) {
// set new Feed list, after refresh
_feed = feed;
}

@Override
public int getCount() {
// Set the total list item count
return _feed.getItemCount();
}

@Override
public Object getItem(int position) {
return position;
}

@Override
public long getItemId(int position) {
return position;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {

// Inflate the item layout and set the views
View listItem = convertView;
int pos = position;
if (listItem == null) {
listItem = layoutInflater.inflate(R.layout.list_item, null);
}

// Initialize the views in the layout
ImageView iv = (ImageView) listItem.findViewById(R.id.thumb);
TextView tvTitle = (TextView) listItem.findViewById(R.id.title);
TextView tvDate = (TextView) listItem.findViewById(R.id.date);
TextView comment_bubble = (TextView) listItem.findViewById(R.id.comment_bubble);

// Set the views in the layout
imageLoader.DisplayImage(_feed.getItem(pos).getImage(), iv);
tvTitle.setText(_feed.getItem(pos).getTitle());

// calculate the time difference to the actual system time
String pubDate = _feed.getItem(pos).getDate();
SimpleDateFormat df = new SimpleDateFormat(
"EEE, dd MMM yyyy HH:mm:ss",Locale.ENGLISH);
try {
try {
pDate = df.parse(pubDate);
} catch (java.text.ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
pubDate = "Vor "
+ DateUtils.getDateDifference(pDate);
} catch (ParseException e) {
Log.e("DATE PARSING", "Error parsing date..");

}
//set time difference
tvDate.setText(pubDate);

//set comment in bubble
comment_bubble.setText(_feed.getItem(pos).getComment());

return listItem;
}
}

Answer

I solved it this way inside my ListFragment:

    @Override
    public void onStart() {
        super.onStart();

        //set first item activated by default
        onListItemClick(listView, getView(), 1, 0);
    }
/**
 * Turns on activate-on-click mode. When this mode is on, list items will be
 * given the 'activated' state when touched.
 */
public void setActivateOnItemClick(boolean activateOnItemClick) {
    // When setting CHOICE_MODE_SINGLE, ListView will automatically
    // give items the 'activated' state when touched.
    listView.setChoiceMode(activateOnItemClick ? ListView.CHOICE_MODE_SINGLE
            : ListView.CHOICE_MODE_NONE);
}
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