I have made my own CustomArrayAdapter to show list of Brazilian Restaurants. I have overidden the GetView method to make my own custom view.
private class MyAdapter extends ArrayAdapter<String> {
public MyAdapter(Context context, int resource, int textViewResourceId,
String[] strings) {
super(context, resource, textViewResourceId, strings);
// TODO Auto-generated constructor stub
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View row = inflater.inflate(R.layout.list_item, parent,false);
String [] items= getResources().getStringArray(R.array.locations_array);
TextView tv= (TextView) row.findViewById(R.id.textView1);
ImageView iv = (ImageView) row.findViewById(R.id.imageView1);
tv.setText(items[position]);
iv.setImageResource(R.drawable.brazil);
return row;
}
}
Currently this new GetView class is pulling in a text string from a resource xml file and putting it into the list item.
If I wanted to incorporate an array of extra data generated within the app, I assume that I don't do the array generating in the GetView class as this will be recreated each time a new row is made.
Where do I put the code to make the array, and how do I call this data into the GetView code above?
It's worth pointing out that for better performance you should be making use of the convertView variable passed into the getView() method.
The use of convertView allows you to re-use list item views instead of creating new ones which has a heavy performance hit. If you have a large data set or value performance in your app, you would do well to check out the documentation for getView()
Your code would then look something more like this:
...
//it's also worth moving these methods to your constructor so they aren't called every time getView() for better performance
LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
String [] items= getResources().getStringArray(R.array.locations_array);
#Override
public View getView(int position, View convertView, ViewGroup parent) {
if(convertView == null)
convertView = inflater.inflate(R.layout.list_item, parent, false);
TextView tv= (TextView) convertView.findViewById(R.id.textView1);
ImageView iv = (ImageView) convertView.findViewById(R.id.imageView1);
tv.setText(items[position]);
iv.setImageResource(R.drawable.brazil);
return row;
}
...
Building on #CodeDownZero's answer, I highly recommend you adopt the ViewHolder pattern, and definitely recycle your listviews (using convertview).
...
#Override
public View getView(int position, View convertView, ViewGroup parent) {
View view = null;
if (convertView == null) {
LayoutInflater inflater = (LayoutInflater) getSystemService
(Context.LAYOUT_INFLATER_SERVICE);
view = inflater.inflate(textViewResourceId, parent, false);
final ViewHolder viewHolder = new ViewHolder();
viewHolder.tv1 = (TextView) view.findViewById(R.id.textView1);
viewHolder.tv2 = (TextView) view.findViewById(R.id.textView2);
view.setTag(viewHolder);
} else {
view = convertView;
}
ViewHolder holder = (ViewHolder) view.getTag();
MyDataClass data = this.getItem(position);
holder.tv1.setText(data.street);
holder.tv2.setText(data.name);
return view;
}
...
private class ViewHolder {
private TextView tv1;
private TextView tv2;
}
You can base an ArrayAdapter on a custom class instead of string. Here is an example:
public class MyDataClass {
public String street;
public String name;
}
private class MyAdapter extends ArrayAdapter<MyDataClass> {
#Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View row = inflater.inflate(R.layout.list_item, parent,false);
TextView tv1= (TextView) row.findViewById(R.id.textView1);
TextView tv2= (TextView) row.findViewById(R.id.textView2);
MyDataClass data = this.getItem(position);
tv1.setText(data.street);
tv2.setText(data.name);
return row;
}
}
To populate the Adapter with data you can use this snippet in the OnCreate method of the Activity:
..
MyAdapter adapter = new MyAdapter();
MyDataClass lData = new MyDataClass(); // here was a mistake
lData.name = "MyName";
lData.street = "MyRoad";
adapter.Add(lData);
..
ListView.Adapter=adapter; // where Listview is the Listview
Related
I am just adapting my custom adapter code with ViewHolder so that i can optimize my list view with a recycler, but i am not sure if i do it right.
My view holder class:
public class ViewHolderTask {
int positionHolder;
TextView nameHolder;
TextView timeHolder;
TextView sessionHolder;
TextView dateHolder;
FloatingActionButton mFabTaskHolder;
public ViewHolderTask(View v, int position) {
this.positionHolder = position;
this.nameHolder = v.findViewById(R.id.taskNameText);
this.timeHolder = v.findViewById(R.id.timeTextView);
this.sessionHolder = v.findViewById(R.id.textViewSession);
this.dateHolder = v.findViewById(R.id.dateTextView);
this.mFabTaskHolder = v.findViewById(R.id.myFabTask);
}
My custom adapter class:
#NonNull
#Override
public View getView(int position, #Nullable View convertView, #NonNull ViewGroup parent) {
ViewHolderTask holder;
if(convertView == null){
LayoutInflater inflater = (LayoutInflater) context.getSystemService(
Context.LAYOUT_INFLATER_SERVICE );
convertView = inflater.inflate(R.layout.task_row, parent, false);
holder = new ViewHolderTask(convertView, position);
convertView.setTag(holder);
}else{
holder = (ViewHolderTask) convertView.getTag();
}
Task task = taskArrayList.get(position);
//set the configurations
holder.getTimeHolder().setText(getTimeString(task.getTime()));
holder.getNameHolder().setText(task.getName());
holder.getDateHolder().setText(getDateString(task.getDate()));
holder.getSessionHolder().setText(getSessionString(task.getSession()));
//Set the FAB listener
addFabListener(holder.getmFabTaskHolder(), position);
//set the clicked background
if(TaskActivity.getIsClicked() && TaskActivity.getPositionClicked()-1 == position){
convertView.setBackgroundResource(R.color.backgroundSelectedItem);
}
return convertView;
}
Do I use it right?
Seems to be fine for me other than this portion of the code
//set the clicked background
if(TaskActivity.getIsClicked() && TaskActivity.getPositionClicked()-1 == position){
convertView.setBackgroundResource(R.color.backgroundSelectedItem);
}
You might need to reset the background resource back to default for the item which is not clicked. maybe you have to add "else" part to the "if"
I have ListView with Adapter, and also use holder. but later I read about recyclerView.ViewHolder and now confused, Is it different with the one I've been using right now? I mean for the optimization purpose, I want to know if using holder only is not good enough without using recyclerView.
public class NewsAdapter extends ArrayAdapter<News> {
Context context;
List<News> myList;
public NewsAdapter(Context context, int resource, List<News> objects) {
super(context, resource, objects);
this.context = context;
this.myList = objects;
}
#Override
public News getItem(int position) {
if(myList != null)
return myList.get(position);
return null;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
Holder holder;
if (convertView == null){
LayoutInflater inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = inflater.inflate(R.layout.list_news, null);
holder = new NewsAdapter.Holder();
holder.title = (TextView)convertView.findViewById(R.id.textViewTitle);
holder.datePosted = (TextView)convertView.findViewById(R.id.textViewDate);
holder.imageView = (ImageView)convertView.findViewById(R.id.imageViewThumbnailpic);
convertView.setTag(holder);
}else{
holder = (Holder)convertView.getTag();
}
News news = getItem(position);
holder.title.setText(news.getTitle());
holder.datePosted.setText(news.getDatePost());
Picasso.with(context)
.load(news.getImgUrl())
.placeholder(R.drawable.coin25)
.error(R.drawable.hnbspic)
.into(holder.imageView);
return convertView;
}
private class Holder{
ImageView imageView;
TextView title;
TextView datePosted;
}
}
It's better to use Recyclerview because it has been optimized for various scenarios and not just for View holder pattern like it give the option for determining how your item should be laid out or like what should be the animation or custom drawing in each item.You can read more this medium post
In ImageView, my images are being shuffled but not the text. This is my getView() method:
public View getView(int position, View convertView, ViewGroup parent) {
View v;
if (convertView == null) {
LayoutInflater inflater = (LayoutInflater) mainActivity.getSystemService( Context.LAYOUT_INFLATER_SERVICE );
v = inflater.inflate(R.layout.item_people, parent, false);
} else {
v = (View) convertView;
}
TextView textView = (TextView) v.findViewById(R.id.name);
ImageView imageView = (ImageView) v.findViewById(R.id.image);
if (list.get(position).getClass() == SearchData.Video.class) {
SearchData.Video video = (SearchData.Video) list.get(position);
textView.setText(video.getVideoName());
if (video.getCoverPicture().length > 0)
imageView.setBackground(mainActivity.Base64toImage(video.getCoverPicture()[0].getImg()));
} else if (list.get(position).getClass() == SearchData.Actor.class) {
SearchData.Actor actor = (SearchData.Actor) list.get(position);
textView.setText(actor.getFirstName());
if (actor.getPicture().length > 0)
imageView.setBackground(mainActivity.Base64toImage(actor.getPicture()[0].getImg()));
}
return v;
}
I am setting image and text of actors. When I scroll down then up the images have shuffled, but not text. Why?
Did you tried the same with ViewHolder
Normally when ever getView() method is called, the gridview/ listview will automatically notified as a change, So that is the reason for your image shuffling s / changing in your gridview.
So, try to implement your Gridview with ViewHolder pattern and avoid those shuffling s / re-orderings
here is the sample code for view holder pattern implementation.
#Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolderItem viewHolder;
// The convertView argument is essentially a "ScrapView" as described is Lucas post
// http://lucasr.org/2012/04/05/performance-tips-for-androids-listview/
// It will have a non-null value when ListView is asking you recycle the row layout.
// So, when convertView is not null, you should simply update its contents instead of inflating a new row layout.
if(convertView==null){
// inflate the layout
LayoutInflater inflater = ((Activity) mContext).getLayoutInflater();
convertView = inflater.inflate(layoutResourceId, parent, false);
// well set up the ViewHolder
viewHolder = new ViewHolderItem();
viewHolder.textViewItem = (TextView) convertView.findViewById(R.id.textViewItem);
// store the holder with the view.
convertView.setTag(viewHolder);
}else{
// we've just avoided calling findViewById() on resource everytime
// just use the viewHolder
viewHolder = (ViewHolderItem) convertView.getTag();
}
// object item based on the position
ObjectItem objectItem = data[position];
// assign values if the object is not null
if(objectItem != null) {
// get the TextView from the ViewHolder and then set the text (item name) and tag (item ID) values
viewHolder.textViewItem.setText(objectItem.itemName);
viewHolder.textViewItem.setTag(objectItem.itemId);
}
return convertView;
}
your ViewHodler should be like this
// ViewHolder.
// caches our TextView
static class ViewHolderItem {
TextView textViewItem;
}
This is not the exactly same to your question, but you can edit the above logic for your way.
Hope it Helps :)
When I debug the code, it is calling constructors in InviteListAdapter but it is not calling getView() method. I have tried multiple solutions available on stackoverflow but none of them works. Hope any one can find the mistake or solution for this.
invitableFriends.size()
returns value greater than 0.
InviteListAdapter
public class inviteListAdapter extends ArrayAdapter<JSONObject> {
private final Context context;
private final List<JSONObject> invitableFriends;
private ImageView profilePicView;
public inviteListAdapter(Context context, List<JSONObject> invitableFriends) {
super(context, R.layout.invite_adapter, invitableFriends);
this.context = context;
this.invitableFriends = invitableFriends;
}
#Override
public View getView(int position, View convertView, ViewGroup parent){
LayoutInflater inflater = (LayoutInflater) context
.getSystemService(context.LAYOUT_INFLATER_SERVICE);
View listItemView = inflater.inflate(R.layout.invite_adapter, parent, false);
profilePicView = (ImageView) listItemView.findViewById(R.id.inviteListItemProfilePic);
TextView nameView = (TextView) listItemView.findViewById(R.id.inviteListItemName);
JSONObject currentUser = invitableFriends.get(position);
nameView.setText(currentUser.optString("first_name"));
return listItemView;
}
}
first.java
public View onCreateView (
LayoutInflater inflater,
ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.activity_first,container, false);
invitesGridView = (GridView)view.findViewById(R.id.invitesGridView);
return view;
}
final inviteListAdapter adapter = new inviteListAdapter(this,inviteFriendList);
invitesGridView.setAdapter(adapter);
adapter.notifyDataSetChanged();
public View onCreateView (
LayoutInflater inflater,
ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.activity_first,container, false);
invitesGridView = (GridView)view.findViewById(R.id.invitesGridView);
final inviteListAdapter adapter = new inviteListAdapter(this,inviteFriendList);
invitesGridView.setAdapter(adapter);
adapter.notifyDataSetChanged();
return view;
}
Call setAdapter inside onCreateView
Here you have to use context class static method. Like, change context to Context.LAYOUT_INFLATER_SERVICE
LayoutInflater inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
Its not good practice to create inflater object in getView() method, Instead create one in constructor using LayoutInflater.from(context);
This link will help you out
How to use ArrayAdapter<myClass>
I have this Adapter that displays custom listview to my layout:
public class AttendedBaseAdapter extends ArrayAdapter<DashboardListing> {
private List<DashboardListing> items;
private Activity activity;
private static View v, vDashboard;
public AttendedBaseAdapter(Activity a, int textViewResourceId, List<DashboardListing> items){
super(a, textViewResourceId, items);
activity = a;
this.items = items;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
v = convertView;
vDashboard = convertView;
final DashboardListing attended = items.get(position);
LayoutInflater vi = (LayoutInflater) activity
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = vi.inflate(R.layout.row_attended, parent, false);
LayoutInflater viDashboard = (LayoutInflater) activity
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
vDashboard = viDashboard.inflate(R.layout.fragment_dashboard, parent, false);
SmartImageView imgVenue = (SmartImageView) v.findViewById(R.id.event_poster_url);
imgVenue.setImageUrl(attended.getPoster());
TextView txtEventName = (TextView) v.findViewById(R.id.event_name);
TextView txtVenueName = (TextView) v.findViewById(R.id.event_venue_name);
txtEventName.setText(attended.getName());
txtVenueName.setText(attended.getVenue());
TextView txtAttendedCount = (TextView) vDashboard.findViewById(R.id.txt_attended_count);
txtAttendedCount.setText("100");
return v;
}
}
In this part of method getView(...):
#Override
public View getView(int position, View convertView, ViewGroup parent) {
v = convertView;
vDashboard = convertView;
final DashboardListing attended = items.get(position);
LayoutInflater vi = (LayoutInflater) activity
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = vi.inflate(R.layout.row_attended, parent, false);
LayoutInflater viDashboard = (LayoutInflater) activity
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
vDashboard = viDashboard.inflate(R.layout.fragment_dashboard, parent, false);
SmartImageView imgVenue = (SmartImageView) v.findViewById(R.id.event_poster_url);
imgVenue.setImageUrl(attended.getPoster());
TextView txtEventName = (TextView) v.findViewById(R.id.event_name);
TextView txtVenueName = (TextView) v.findViewById(R.id.event_venue_name);
txtEventName.setText(attended.getName());
txtVenueName.setText(attended.getVenue());
TextView txtAttendedCount = (TextView) vDashboard.findViewById(R.id.txt_attended_count);
txtAttendedCount.setText("100");
return v;
}
How can I return multple(not just the View v but I also want to return the View vDashboard? because I have 2 layouts View v refers to R.layout.row_attended and View vDashboard refers to R.layout.fragment_dashboard
How can I return multple(not just the View v but I also want to return the View vDashboard?
You would need to wrap them in some sort of container (e.g., LinearLayout) with rules for how they should be sized and positioned within that container, then return the container from getView().
Even easier would be to combine the layout files, directly or using <include> elements, so that you only are inflating one layout.
In other words, getView() returns the one View that is to be the ListView row (or GridView cell or whatever) for the given position. That View can be a ViewGroup populated by whatever you want, so long as it meets your UI requirements.