I woud like to create a listview that alternates background images. For example, the first item would have background image a and the second item would have background image b and the third backgroud a. In basic terms I would like help on creating a listview that for every odd item (egg first, third, fith) has a certian background image different to those listview items which are even (egg second, fourth, and sixth listview item). Here's an exampe.
http://www.gadgetreview.com/wp-content/uploads/2011/10/SIRI-Reminders.jpg
In this example the speech bubbles are background image and each different background image is a different listview item.
In your list adapter in the getView method divide the position attribute that gets sent into the method by 2. If the remaining number is 0 than you are in the even row of your listview. Depending on that you can change the layout of your list view item.
#Override
public View getView(int position, View convertView, ViewGroup parent) {
if(position % 2 = 0)
//set layout for even row
}else{
//set layout for odd row
}
Last time that I tried I didn't find an xml parameter to do that, but you can try to use the same workaround used in this question:
Stack Overflow: How do I alternate colors in between Listviews?
you have to make your own custom adapter and then in the following method:
public View getView(int position, View convertView, ViewGroup parent) {
}
you can use position to change the background if position is odd
There is SetEmptyView method in list view use it
listView.setEmptyView( findViewById( R.id.empty_list_view ) );
Related
I am using horizontal list view and adding dynamic data into this, but I want to add an item when the scroll reached to the right most item in the listview.
How can I get that scroll reached to the right most position?
Implement an onScrollListener to your listview, and fetch data through onScroll() method.
There are many libraries for doing this easily. The following is a vertical listview example, but you can always change it to Horizontal and modify the code according to your needs.
https://github.com/shontauro/android-pulltorefresh-and-loadmore
In order to do that, you have to mock the size of the list ruled by your adapter. For example, if the list is called myList, its size is myList.size(), you will have to do something like: myList.add(mockelemnt).
Now that you have mocked the last element, what you may do is to handle it on your adapter method getView():
#Override
public View getView(int position, View convertView, ViewGroup parent){
if (oistion < myList.size(){
//work with conventional view
}else if (postion == myList.size()){
//work with addMore view
}
}
Hope it helps
Inside my getView method I want to get a specific child view. I know that my adapter holds several items, by doing calling getCount:
getCount();
According to the JavaDoc:
public abstract int getCount ()
Added in API level 1
How many items are in the data set represented by this Adapter.
Now in my getView method:
public View getView(final int position, View convertView, ViewGroup parent) {
View lastAddedItem = parent.getChildAt(getCount()-1);
if(lastAddedItem == null) {
Log.w("ListAdapter", "View is null");
}
}
This message always appears in the LogCat, which means that the View I try to grab is Null.
I've also tried this:
View lastAddedItem = parent.getChildAt(parent.getChildCount()-1);
So how can I grab a specific view from my ViewGroup object?
I know that my adapter holds several items, by doing calling
getCount:
Yes it does, but the getCount()(returning the items in the Adapter) method of an adapter has nothing to do with getting the children of a ListView with getChildAt()(where you should use getChildCount() as this will return the Views present in the ViewGroup).
lastAddedItem = parent.getChildAt(parent.getChildCount()-1);
This should return a non-null view, the last view returned by the getView() method.
I just want to animate a specific View in my ViewGroup
If you are going to animate a list row(or part of that row) when it becomes visible than register a scroll listener for the ListView and start the animation from there when the target view is appearing on the screen.
I don't how are you implemented the rest of the adapter, but if you are doing it in the right way, and I am right, the parent only contains the Views being displayed on the device's screen, and each time you pull down or pull up the list, it modifies the content of those views, that is why you get Null.
What you want to achieve (animate a view), should be done in runtime, checking if the view currently being displayed in the screen should be animated or not.
Hope it helps.
I am getting some strange behavior from list view. I need to change background color of rows which confirmed the requirement below but it applied on one or two other rows too. which disappeared on scroll.
public View getView(int position, View convertView, ViewGroup parent) {
if (item.get("how_out").equals("not out")) {
v.setBackgroundColor(Color.LTGRAY);
return v;
}
}
thanks
This behavior is due to the recycling property of the listview. The ListView recycles its textviews onScroll. Hence you need to store the states of the textviews using a boolean array and handle the textviews inside onScroll listener of the Listview.
How can I color code individual rows in a ListView exactly like it is done in the native MESSAGING app? I do NOT want to simply do alternating rows, but I want to copy the format used in the MESSAGING app, where message rows have a different background color based on the username of the message.
FYI:
I am currently extending SimpleAdapter and overriding getView(int position, View convertView, ViewGroup parent). In this method, I am trying to calculate setting the background color based on the position as compared to a list of 'positions to highlight' that I am maintaining each time I update the list, but so far this is only working the first time the list is updated.
In class that overrides SimpleAdapter:
#Override
public View getView(int position, View convertView, ViewGroup parent) {
View view = super.getView(position, convertView, parent);
if(highlightPositions.contains(new Integer(position))){
view.setBackgroundColor(highlightColor);
}
else{
view.setBackgroundColor(normalColor);
}
return view;
}
Thank you for any guidance you can offer!
I think you need to call notifyDataSetChanged() on your ListAdapter. This forces the list to refresh, calling your overridden getView() method.
Thanks for the help. Actually, the code I listed does in fact work. The problem turned out to be a small mistake in my keeping track of the list positions to highlight in the highlightPositions list. Once I corrected that, and in fact highlightPositions list did indeed contain the correct positions to highlight, then it worked properly.
The problem I hope to resolve here is that when I click on one item in the ListView that item's background changes to light gray, but when I continue to scroll through the list every 4th item has the background changed to light gray even though those other items have not been clicked. How do I make only the item I clicked be effected by the click?
ListView lv = (ListView) findViewById(R.id.resultsList);
lv.setAdapter(new ArrayAdapter<String>(this, R.layout.resultitem, (String[])labelList.toArray(new String[labelList.size()])));
lv.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
TextView tv = (TextView)view.findViewById(R.id.result);
tv.setBackgroundColor(Color.LTGRAY);
tv.setTextColor(Color.BLACK);
}
}
You'll have to override getView() in a subclass of ListAdapter, in this case, ArrayAdapter.
This is because Android actually reuses rows to conserve resources and CPU (when a row is scrolled off the screen, it is reused for new rows that come into view). So, if you set the background grey on one row, it'll probably end up being used again, and the background will still be grey.
If you subclass ArrayAdapter, you can have your onItemClickListener set some sort of flag, and then your ArrayAdapter's getView(), you can set the appropriate background color based on the flag.
This link has an example of subclassing ArrayAdapter
I suppose you are using convert view just like this
...public View getView(int position, View convertView, ViewGroup parent) { ....
and you are changing its background at 4th position, and your view let says have 6 rows on one page, so every 4th row of every page will be grayed out because of reusing the same convertView .
I don't know that I am explaining right, but if you are using convertview and changing its layout, so you should have logic to re-create that layout again to avoid re-using same (cached) view.