I'm creating a custom adapter and using the getView method in attempt to display a default text only ONCE. Now I'm having a problem such that when I click the first Item in the list, the default text is kept but that doesn't hold for any other items? Any suggestions?
Thanks! (My code is a bit messy as I was just trying to debug)
boolean firstTime = true;
#Override
public View getView(int position, View convertView, ViewGroup parent) {
if (firstTime) {
firstTime = false;
TextView firstView = new TextView(ForgotPasswordActivity.this);
firstView.setText("Please select School");
return firstView;
}
TextView view = new TextView(ForgotPasswordActivity.this);
view.setText("Hello");
return view;
}
You must play with the getCount function :
#Override
public int getCount() {
return super.getCount() -1; // This makes the trick;
}
this trick will not show last item that you've added inside your spinner(so when you finish adding your text inside the spinner, add the text that will not be shown in the spinner, and by that it will be show as a default value before clicking the spinner).
Good luck
I'm not exactly sure what your trying to do but you could force the top row to always show the select message by checking if the position is 0. Also notice in the code below that I'm reusing the convertView if it is not null. It's faster to reuse the convertView if it is available than to recreate a new view every time.
#Override
public View getView(int position, View convertView, ViewGroup parent) {
if(convertView == null) {
convertView = new TextView(ForgotPasswordActivity.this);
}
if(position == 0) {
convertView.setText("Please select School");
} else {
convertView.setText("Hello");
}
return convertView;
}
Also remember that by forcing position zero to show the select message you are not showing the actual data in the adapter at position 0. Make sure this is what you want to do or insert a dummy piece of data in the first position of the backing data array.
Related
I'm using listview custom adapter which with row click i'm changing row color. But when i'm scrolling bot and up again it doesnt have the right position.
It changes color in other rows...
public override View GetView(int position, View convertView, ViewGroup parent)
{
DataViewHolder holder = null;
if (convertView == null)
{
convertView = LayoutInflater.From(mContext).Inflate(Resource.Layout.TableItems, null, false);
holder = new DataViewHolder();
holder.txtDescription = convertView.FindViewById<TextView>(Resource.Id.txtDescription);
holder.txtDescription.Click += delegate
{
holder.txtDescription.SetBackgroundColor(Color.Red);
};
convertView.Tag = holder;
}
else
{
holder = convertView.Tag as DataViewHolder;
}
holder.txtDescription.Text = mitems[position].Description;
return convertView;
}
public class DataViewHolder : Java.Lang.Object
{
public TextView txtDescription { get; set; }
}
It looks like it doesnt keep in memory specific row situation.
Don't change the color in the click handler directly, instead change the data from which the adapter draws from and use that to change the color when GetView is called again.
ListView recycles the views it uses to optimize scrolling, instead it just expects the view to represent the data. If you change a color of one view directly, the view then gets recycled and you'll see "another view" (another part of the data) with a different background color.
So in summary: give each data point a color attribute and use that to set the color of each view in GetView, change the data and notify the adapter about the changes to the data.
Edit
I've never used Xamarin but maybe something like this would work
public override View GetView(int position, View convertView, ViewGroup parent)
{
DataViewHolder holder = null;
if (convertView == null)
{
convertView = LayoutInflater.From(mContext).Inflate(Resource.Layout.TableItems, null, false);
holder = new DataViewHolder();
holder.txtDescription = convertView.FindViewById<TextView>(Resource.Id.txtDescription);
holder.txtDescription.Click += delegate
{
// instead of setting the color directly here, just modify the data
(holder.txtDescription.Tag as ItemType).ItemColor = Color.Red
notifyDataSetChanged();
};
convertView.Tag = holder;
}
else
{
holder = convertView.Tag as DataViewHolder;
}
holder.txtDescription.Text = mitems[position].Description;
holder.txtDescription.Tag = mitems[position]; // this so that the click handler knows which item to modify
holder.txtDescription.SetBackgroundColor(mitems[position].ItemColor);
return convertView;
}
public class DataViewHolder : Java.Lang.Object
{
public TextView txtDescription { get; set; }
}
ListView will reuse the item layout, you can use List and View.Tag to avoid the problem caused by reusing.
I have posted my demo on github.
ListView is generated from JSON with boolean getExpired.
if getExpired() is TRUE, then textColor should be changed.
but it set on list position even if == FALSE
Why 1st position is changed, if getExpired is FALSE on this item?
this is my getView
public View getView(int position, View convertView, ViewGroup parent) {
ColorMatrix matrix = new ColorMatrix();
matrix.setSaturation(0);
ColorMatrixColorFilter filter = new ColorMatrixColorFilter(matrix);
if (item.getExpired()) {
vh.imageView.setColorFilter(filter);
vh.profilePhoto.setColorFilter(filter);
vh.expired.setVisibility(View.VISIBLE);
vh.username.setTextColor(Color.parseColor("#76808D"));
}
return vh.rootView;
}
If you're using the ViewHolder pattern you will be getting recycled views which have already have their views set to a certain state. In short, when using ViewHolder also use an else condition to set your view states how you want them to be.
I am new to android. I have implemented custom ArrayAdapter in my Android Application using view holder.
The getView() function of my ArrayAdapter is as follows for reference:
#Override
public View getView(int position, View convertView, final ViewGroup parent) {
View row = convertView;
MyClassViewHolder myClassViewHolder;
MyClass myClass;
if(row == null) {
LayoutInflater inflater = ((Activity)mContext).getLayoutInflater();
row = inflater.inflate(resourceId, parent, false);
if(resourceId == R.layout.my_row_item) {
myClassViewHolder = new MyClassViewHolder();
myClassViewHolder.title = (EditText) row.findViewById(R.id.title);
myClassViewHolder.switch = (Switch) row.findViewById(R.id.switch);
}
} else {
myViewHolder = (MyViewHolder) row.getTag();
}
if(resourceId == R.layout.my_row_item) {
myClass = (MyClass) myClassList.get(position); //myClassList sent as parameter to constructor of adapter
if(myClassViewHolder != null && myClass != null) {
myClassViewHolder.title.setText(myClass.getTitle());
myClassViewHolder.switch.setChecked(myClass.isEnabled());
myClassViewholder.id = myClass.getId();
myClassViewHolder.switch.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
//GET ID OF THE ROW ITEM HERE
}
});
}
}
}
First of all I want to associate an id which is from database to
every row item to perform actions on them. So please confirm if the
way I have done is is right or wrong.
Secondly in the above code I have a String as title and a Switch in every row
item. I want to set an onClickListener on each switch. On toggling
the switch i want to get the id of the row item which is associated as per point 1.
Thanks in advance. Please let me know if I haven't described my problem properly.
Yes your code looks fine as for second part you should make a listener on switch and then get the id form the row and do switch from one id to another.
You may need to set a tag for each row item and thus you can identify each row. Here is an example -
row.setTag(1);
and to retrive the tag -
row.getTag();
By default, when you select an item in spinner, it highlights briefly before disappearing.
I changed the color of my spinner rows to alternate color with the following code, and the highlight disappears. R.layout.textviewinside and R.layout.textview don't cause this, just the #Override for getDropDownView, because everything works if I comment out that block.
How can I restore that functionality but keep the row colors?
products = new ArrayAdapter<String>(this, R.layout.textview, thedata){
#Override
public View getDropDownView(int position, View convertView, ViewGroup parent) {
View v = super.getDropDownView(position, convertView, parent);
if (position % 2 == 0) { // we're on an even row
v.setBackgroundColor(0xffEBF4FA);//Color.BLUE)
} else {
v.setBackgroundColor(Color.WHITE);
}
((TextView) v).setGravity(Gravity.CENTER);
return v;
}
};
products.setDropDownViewResource(R.layout.textviewinside);
spitem.setAdapter(products);
Instead of using setBackgroundColor, you'll need to use setBackgroundDrawable, and use an xml state list drawable file with pressed/default states.
http://developer.android.com/guide/topics/resources/drawable-resource.html#StateList
I'm working on an application which will display some expandable lists. The fact is sometimes the object won't have any child. So I would like to display in my expandable list only elements which have childs.
I tried to put an if inside the getGroupView function and if the object has no child, I return null but I get a nullPointerException error...
Here is the function:
public View getGroupView(int i, boolean b, View view, ViewGroup viewGroup) {
// Check if the object as child
System.out.println("Result list :: " + mParent.get(i).getListe());
if(mParent.get(i).getListe().isEmpty()){
return null;
}
if (view == null) {
view = inflater.inflate(R.layout.list_item_parent, viewGroup,false);
}
TextView textView = (TextView) view.findViewById(R.id.list_item_text_view);
//"i" is the position of the parent/group in the list
textView.setText(getGroup(i).toString());
// Set the Image View with the brand logo
ImageView logo = (ImageView) view.findViewById(R.id.brandlogo);
// Set image Source
logo.setImageResource(mParent.get(i).getLogoPath());
// Set Image size
logo.getLayoutParams().height = 42;
logo.getLayoutParams().width = 226;
//return the entire view
return view;
}
Is there a way do skip this function?
Thanks
In getGroupCount() function return the number of items with childes (number of items has childes).
And in getGroubView() return the correct view (never return a null here).