Develop Reference

Custom ArrayAdapter Not Just First Element Different

I'm working on making a custom ArrayAdapter so that my list has the first element in a different color.
The thing is, when I execute this code in the get view method:
#Override
public View getView(int position, View convertView, ViewGroup parent){
Club club = (Club)getItem(position);
if(convertView == null){
convertView = LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);
}
TextView textView = (TextView)convertView.findViewById(R.id.txtListItem);
if(position == 0 && club.getName().contains("All")){
textView.setTextColor(ContextCompat.getColor(getContext(), R.color.orange));
}
textView.setText(club.getName());
return convertView;
}
The first item is orange, yes, but the 10th one (below the screen) is also when I scroll down :( in another list with more elements than what the screen can hold, I have several that are orange.. I don't understand why, please help!

This is happening because views are recycling/reused. You are setting orange color for the first item but not setting default color for the rest. Just add an else clause to your if statement above, something like this
if(position == 0 && club.getName().contains("All")){
Log.d(ClubAdapter.class.getName(), club.getName());
textView.setTextColor(ContextCompat.getColor(getContext(), R.color.orange));
}else{
textView.setTextColor(ContextCompat.getColor(getContext(), R.color.your_default_color));
}

Most likely this happens because Android is recycling the view which was originally used for the first row. You need an else clause to set the color back to normal.

This happens because the adapter tries to reuse as many views as possible for performance improvement. That's why you should not create a view in getView, but reuse them (only create if it is null):
if(convertView == null){
convertView = LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);
}
Even though you shouldn't create a new view, you have to make sure that you set the parameters that you want for each getView call (also called "binding"), so:
if(position == 0){
//set your first view color and whatever
}else{
//set your common view colors..
}

Because listview recycle views Google suggests to use the ViewHolder pattern. You should also set a default color if the cell is different. It would look something like this.
#Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder viewHolder;
if(convertView == null){
convertView = LayoutInflater.from(context).inflate(R.layout.list_item, parent, false);
viewHolder = new ViewHolder();
viewHolder.textView = (TextView) convertView.findViewById(R.id.txtListItem);
convertView.setTag(viewHolder);
}
else {
viewHolder = (ViewHolder) convertView.getTag();
}
if(position == 0 && club.getName().contains("All")){
viewHolder.textView.setTextColor(ContextCompat.getColor(getContext(), R.color.orange));
}else{
//Set default color
}
viewHolder.textView.setText(club.getName());
return convertView;
}
static class ViewHolder {
protected TextView textView;
}

convertView in custom adapter with multiple line views

I'm implementing custom adapter which handles multiple type of lines in a listview based on this (very useful) tutorial: http://logc.at/2011/10/10/handling-listviews-with-multiple-row-types/
Now, I thought I understood everything but one thing puzzles me.
In the getView method we receive the convertView which suppose to be the view (group) with specific layout to display in the specific line in the listview.
public View getView(int position, View convertView, ViewGroup parent) {
//first get the animal from our data model
Animal animal = animals.get(position);
//if we have an image so we setup an the view for an image row
if (animal.getImageId() != null) {
ImageRowViewHolder holder;
View view;
//don't have a convert view so we're going to have to create a new one
if (convertView == null) {
ViewGroup viewGroup = (ViewGroup)LayoutInflater.from(AnimalHome.this)
.inflate(R.layout.image_row, null);
//using the ViewHolder pattern to reduce lookups
holder = new ImageRowViewHolder((ImageView)viewGroup.findViewById(R.id.image),
(TextView)viewGroup.findViewById(R.id.title));
viewGroup.setTag(holder);
view = viewGroup;
}
//we have a convertView so we're just going to use it's content
else {
//get the holder so we can set the image
holder = (ImageRowViewHolder)convertView.getTag();
view = convertView;
}
//actually set the contents based on our animal
holder.imageView.setImageResource(animal.getImageId());
holder.titleView.setText(animal.getName());
return view;
}
//basically the same as above but for a layout with title and description
else {
DescriptionRowViewHolder holder;
View view;
if (convertView == null) {
ViewGroup viewGroup = (ViewGroup)LayoutInflater.from(AnimalHome.this)
.inflate(R.layout.text_row, null);
holder = new DescriptionRowViewHolder((TextView)viewGroup.findViewById(R.id.title),
(TextView)viewGroup.findViewById(R.id.description));
viewGroup.setTag(holder);
view = viewGroup;
} else {
view = convertView;
holder = (DescriptionRowViewHolder)convertView.getTag();
}
holder.descriptionView.setText(animal.getDescription());
holder.titleView.setText(animal.getName());
return view;
}
}
However, in the case of multiple types of lines in the listview (for example, list of animals with separators lines with titles like 'mamals','fish','birds') how does the listview know what convertView to send? it can be one of two completely different types. something is very unclear to me. can someone explain please?

From the tutorial you provided :)
The two additional methods android Adapters provide for managing different row types are:
getItemViewType(int position) and getViewTypeCount().
The list view uses these methods create different pools of views to reuse for different types of rows.
Good Luck :)

Android ExpandableListView with custom group header

I'm an Android newbie. I want to create an expandable ListView where 1 row has custom info that has to be specified in the manin thread instead of being hardcoded in a layout.
I want to have an image and 2 textviews in it. I think I will need a custom layout file, but I'm not sure where to make a call for it in my code. Please assist.
What follows is my GropView fxn inside my custom adapter. I want case 0 to load a custom layout file
public View getGroupView(int groupPosition, boolean arg1, View convertView,
ViewGroup arg3) {
String laptopName = (String) getGroup(groupPosition);
if (convertView == null) {
LayoutInflater infalInflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = infalInflater.inflate(R.layout.group_item, null);
}
TextView item = (TextView) convertView.findViewById(R.id.laptop);
item.setTypeface(null, Typeface.BOLD);
item.setText(laptopName);
this.context = (Activity) context;
switch (groupPosition) {
case 0:
convertView.setBackgroundColor(this.context.getResources()
.getColor(R.color.dark_blue));
convertView.inflate(R.layout.first_row_layout, 0, arg3);
break;
case 1:
convertView.setBackgroundColor(this.context.getResources()
.getColor(R.color.purple));
break;
case 2:
convertView.setBackgroundColor(this.context.getResources()
.getColor(R.color.green));
break;
default:
break;
}
return convertView;
}

The position in your code where you define the layout for your group items is this:
if (convertView == null) {
LayoutInflater infalInflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = infalInflater.inflate(R.layout.group_item, null);
}
In your case you are using the layout R.layout.group_item for your group items. If you want to load different layouts for each group position u need to move this part of your code inside the switch-case. You have to be careful with images inside your ListView, more info about that here:
http://developer.android.com/training/improving-layouts/smooth-scrolling.html

Displaying multiple xml views w/o fragments

In my app the user spins a carousel. On the selected Item I need to display a separate xml view for each item. The carousel is visibile at all time at the bottom with the view visible in the top half. I think that there is a better way than to use fragments. Any ideas? The following code is not functional as of now but I think an inflator may be the way to go but to get it done is troubling me. After case0 there is case1-case5.
carousel.setOnItemSelectedListener(new OnItemSelectedListener(){
public void onItemSelected(CarouselAdapter<?> parent, View view,
int position, long id) {
switch(position){
case 0:
final View firstview;
LayoutInflater inflater = (LayoutInflater) getBaseContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
firstview = inflater.inflate(R.layout.selected_item, null);
break;
case 1:

In case anyone else runs into this problem I solved it:
LayoutInflater inflater = (LayoutInflater) CarouselActivity.this.getSystemService( Context.LAYOUT_INFLATER_SERVICE );
LinearLayout inflateView = (LinearLayout) findViewById( R.id.InflateParent );
View nextView = null;
switch(position){
case 0:
System.out.println("Case 0");
inflateView.removeAllViews();
nextView = inflater.inflate( R.layout.nextview, null );
inflateView.addView(nextView);

ListView with a TextEdit header messes up

I have a ListView, and I have added a header (with getListView().addHeaderView) that simply contains a TextEdit widget.
Then when I tap the TextEdit to start writting, the keyboard appears and it messes up the list!
If I tap everywhere else to hide the keyboard, the list messes up again!
I don't know why is this happening. I thought it was something related with the onConfigurationChanged method, but after implementing it (and adding the corresponding attribute in the manifest file) the problem persists.
How could I fix it? Why is Android messing up my list?
EDIT:
My list uses a custom adapter, this is the getView method:
#Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
if (v != null) {
return v;
}
LayoutInflater vi = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = vi.inflate(R.layout.list_row, null);
ListTask list_item = items.get(position);
if (list_item != null) {
TextView item_name = (TextView) v.findViewById(R.id.item_name);
item_name.setText(list_item.getTitle());
}
return v;
}
The problem is not the value of my items, but their order. They are displayed in a different order when the keyboard appears, but the values are correct.
EDIT2:
Ok, I have changed my getView method with rekaszeru's suggestion and now it works as expected. But now I'm facing another problem: what if my items have two textviews?
Let's say the second textview is optional, and "Item 1" and "Item 3" have it, but "Item 2" does not, so it's initialized as a void String (length == 0).
The first time the list is displayed, it shows "Item1" and "Item 3" with their second textview, and "Item 2" without it. That's correct. But when the keyboard appears, the "Item 2" takes the second textview of another item and displays it!
This is the modified code I have right now:
#Override
public View getView(int position, View convertView, ViewGroup parent) {
if (convertView == null) {
LayoutInflater vi = (LayoutInflater) getContext().
getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = vi.inflate(R.layout.list_row, null);
}
ListTask list_item = items.get(position);
TextView item_name = (TextView) convertView.findViewById(R.id.item_name);
TextView item_optional_text = (TextView) convertView.findViewById(R.id.item_optional_text);
item_name.setText(list_item.getTitle());
// if the item has defined the optional text, make some room and display it
if (item_optional_text.isNotEmpty()) {
LayoutParams layout_params = (LayoutParams) item_name.getLayoutParams();
layout_params.topMargin = 10;
layout_params.height = -2; // -2: wrap_content
item_name.setLayoutParams(layout_params);
item_optional_text.setText(list_item.getOptionalText());
}
return convertView;
}
The isNotEmpty() does this in the Item class:
public boolean isNotEmpty() {
return this.optional_text.length() > 0;
}
Maybe it's too complex to understand in a written question. If so, I can make a short video showing the problem and my source code. Thanks in advance for your help guys.

Your row recycling is messed up. Android is not changing the order of the items, you are.
Right now, if you are passed a row to recycle, you return it without modification. This is a mistake. You are supposed to modify the contents of the row to reflect the data at the supplied position. The only piece of logic you can skip in this case is inflating a brand-new row.
Here is a free excerpt from one of my books that goes through all of this.

You should override the getView method in your ListAdapter implementation, and make sure that you always assign a new value to the view that you are returning (or at least always update it to contain the proper data).
#Override
public View getView(int position, View convertView, ViewGroup parent)
{
convertView = inflater.inflate(R.layout.list_row, parent, false);
//set the necessary data in your TextViews, Checkboxes, etc...
return convertView;
}
If you don't inflate your item renderer, then you can instantiate it from code, like:
#Override
public View getView(int position, View convertView, ViewGroup parent)
{
convertView = new TextView([...]);
convertView.setText(textBasedOnYourData);
return convertView;
}
Edit
As #CommonsWare noted, attention should be payed to the recycling of your list item renderer. So instead of instantiating it every time, you should check whether it already exists or not, and update the underlying TextView afterwards.
So I'd suggest give a try to this slightly modified getView implementation:
#Override
public View getView(int position, View convertView, ViewGroup parent) {
if (convertView == null) {
LayoutInflater vi = (LayoutInflater) getContext().
getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = vi.inflate(R.layout.list_row, null);
}
ListTask list_item = items.get(position);
TextView item_name = (TextView) convertView.findViewById(R.id.item_name);
//the item should never be null, but just in case:
item_name.setText((list_item == null) ? "" : list_item.getTitle());
return convertView;
}