I have an Android ListView created with a SimpleAdapter that has more items in it than fit in the screen. After the list has been scrolled, I need to get the position in the data model of the first visible item in the list.
Basically I want a function like: listView.getChildAt(0).getPositionInDataModel().
Adapter has a few functions in it, like getItemId(position) that looked useful; however, the SimpleAdapter implementation just returns the passed in position, not a row id like I'd hoped.
A brute force solution would be to get the View at index 0, and compare it to the view for each item in the adapter. However, there doesn't seem to be an easy way to get the view for a particular position from the adapter.
Anyone have any thoughts?
It's very easy. Just use ListView.getFirstVisiblePosition() + indexYouWant. For instance, to get the position in the adapter of the 2nd child displayed in the ListView, just use getFirstVisiblePosition() + 1.
No need for all the scary stuff shown in the reply above :)
listView.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener()
{
public void onItemSelected(AdapterView<?> parent,View view, int pos, long id)
{
AisleId= parent.getSelectedItemId();
}
#Override
public void onNothingSelected(AdapterView<?> arg0) {
// TODO Auto-generated method stub
}
});
In this we will get list item Id parent.getSelectedItemId();
Simply use the getPositionForView(View) (see documentation). The main advantage of this method is it also works with descendant Views of an item.
Related
I've read lots of tutorials from my manual and on the internet that explain the getView method, but I haven't understood why they use it.
Could anyone explain it to me with some examples or snippets?
getItem() returns the item's data object. It provides a way for you to access data in the adapter. For example, your array adapter holds string elements, getItem() returns a string object.
getView() is used to construct or reuse the child item of your AdapterView.
AdapterView is a view that contains multiple items. For example, a ListView contains some items that have the same (or might not) structure. getView() is used to build the View at some position and fill it with data.
getItem() is used to get the item that provides a data for the specified View item.
For example, getItem() must return a String or CharSequence if you have a ListView of text items. This is made for convenience, for example in your onItemClickListener
#Override
public void onItemClick(AdapterView<?> av, View view, int pos,
long arg3) {
String selectedText = (String) av.getItemAtPosition(pos);
// or av.getAdapter().getItem(pos);
}
I have a custom ListView with two TextViews both containing different values. What I want to be able to do it get the contents from one of these TextViews when an item is clicked.
This is the code I have so far:
listView.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
String value;
// value = (get value of TextView here)
}
});
I want to be able to assign value to the text of one of the TextView's.
Although #Sam's suggestions will work fine in most scenarios, I actually prefer using the supplied AdapterView in onItemClick(...) for this:
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Person person = (Person) parent.getItemAtPosition(position);
// ...
}
I consider this to be a slightly more fool-proof approach, as the AdapterView will take into account any header views that may potentially be added using ListView.addHeaderView(...).
For example, if your ListView contains one header, tapping on the first item supplied by the adapter will result in the position variable having a value of 1 (rather than 0, which is the default case for no headers), since the header occupies position 0. Hence, it's very easy to mistakenly retrieve the wrong data for a position and introduce an ArrayIndexOutOfBoundsException for the last list item. By retrieving the item from the AdapterView, the position is automatically correctly offset. You can of course manually correct it too, but why not use the tools provided? :)
Just FYI and FWIW.
You have a few options. I reference the code from your previous question.
You can access this data from the row's layout view:
ViewHolder holder = (ViewHolder) view.getTag();
// Now use holder.name.getText().toString() and holder.description as you please
You can access the Adapter with position:
Person person = mAdapter.getItem(position);
// Now use person.name and person.description as you please
(By the way in your Person class, name and description are public so you don't need the get methods.)
Override following method in adaterclass.
public String[] getText() {
return text;
}
I have a list view that uses different layout sheets for different rows. Each sheet has different variables on them. So, when I want to implement the click listener for my list I need to know which type of row I am clicking on so that I can try to access to the correct values. For example:
list.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
//do this for layout A
//......
// do that for layout B
//......
}
});
How can I access to the layout information and the corresponding values ?
Make sure that you have a variable in your activity where you've kept the data with which you've populated the adapter.
Then, based on the position variable, you'll be able to get the exact row which was clicked. Then based on the row, you'll be able to figure out what type of row it is, right? :)
you can use the method:
public abstract int getItemViewType (int position) of your custom adapter.
I have implemented a custom adapter for my ListView, that includes a CheckBox in each row.
As I have my click listener in my custom adapter, I'm forced to implement there my business logic (that is, what happens when a CheckBox is clicked... access the database, etc).
Is that correct? Wouldn't be a better practice to implement that business logic outside the custom adapter? (I think the adapter should only care about visualization).
Try this..hope it helps you
lv_Archiveist.setOnItemClickListener(new OnItemClickListener(){
#Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
// TODO Auto-generated method stub
if(view.findViewById(R.id.chkbox).isChecked())
{
//your method//
//you can also get the position of your selected checkbox by the parameter "position"
}
I'd only mark the item on CheckBox click, and perform all the logic on different button click that would be outside of a ListView (similar to how iPhone handle editing the table). I can't remember the situation where CheckBox is used to perform some action itself.
i have two spinners.
If in the first one the Item "Diesel" is selected i want to display the second one.
sKraftstoffArt.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
if(sKraftstoffArt.getSelectedItem().toString() == "Diesel"){
sPartikelfilterArt.setVisibility(sPartikelfilterArt.VISIBLE);
}
}
public void onNothingSelected(AdapterView<?> adapterView) {
return;
}
});
I've implemented this code in the onCreate method. When i select a item during the runtime i'm not getting the selected item text... It works only if the activity gets created and the default value gets selected....
Where else do i have to implement it?
Regards,
float
Unless your sKraftstoffArt object is not a final one, the check against it's selected item text inside an anonymous class won't work.
The adapterView among the parameters is your ListView instance to which you've assigned the AdapterView.OnItemClickListener.
The view parameter is the actual item (renderer) inside your ListView that has been clicked. This item is provided by your adapter's getView(int position, View convertView, ViewGroup parent) method.
Also, you should use the equals method of String to check whether two String values are equal.
So this won't work:
if(sKraftstoffArt.getSelectedItem().toString() == "Diesel")
Use insetad
if (adapterView.getSelectedItem().toString().equals("Diesel"))
You might also want to add an else clause after this if, to hide the sPartikelfilterArt spinner when the selected item in the previous spinner is not "Diesel".
Please note, that every time you assign a new adapter to this list (which probably you don't, i still mention it just in case...), you should add the AdapterView.OnItemClickListener to it again.