Develop Reference

Programatically replace String Array in a ListView Array Adapter

I have a ListView that i have populated with a string array: {"1","2","3"} using an Array Adapter.
(ListView) ListOptions = (ListView)findViewById(R.id.ListOptions);
String[] exampleString = new String[]{"1","2","3"};
ListAdapter adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,exampleString);
ListOptions.setAdapter(adapter);
Later on, i want to be able to change exampleString to exampleString2:
{"4","5","6"}
and have the ListView update with exampleString2 displayed as the list options.
is there something i can do along the lines of:
adapter.ChangeStringArray(exampleString2);
ListView.setAdapter(adapter);
I want to avoid having to create a new adapter each time I change the String array that is populating the list items.

ArrayAdapter has methods for managing the backing data array.
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1, new ArrayList<String>());
adapter.addAll(exampleString);
adapter.clear();
adapter.addAll(exampleString2);
adapter.notifyDataSetChanged();

How to remove item from adapter

I have a container, adapter, and couple items. I would like to save items into database one by one.
However, I have issue on getting next item from adapter and resize adapter.
So far I have the code below:
adapter.add(item[0]);
adapter.add(item[1]);
adapter.add(item[2]);
item = adaper.getItem(0);
item.setDismissListener(new Item.OnDimissedListener(){
#Override
public void save(){
1. save item to database, it works here
2. get next item, I do
item = adapter.removeFirst(); // this one returns null pointer exception.
}
}
container.setAdapter(adapter); // set adapter here
Do you guys have any idea?

I had a similar project where I stored strings in a SQLite database and users could add/delete/modify items. What I did was to temporarily store the list of items in an ArrayList<String> and then update the ListView adapter with adapter.notifyDataSetChanged(); when that ArrayList changes.
In your case, I'd try something like this:
// Create an ArrayList <String>
ArrayList<String> itemsArray = new ArrayList<String>();
itemsArray.add( YOUR_ITEMS_GO_HERE );
...
// add data in ArrayAdapter
adapter = new ArrayAdapter<String>(this, R.layout.list, itemsArray);
ListView dataList = (ListView) findViewById(R.id.list);
dataList.setAdapter(adapter);
// Perform your Save actions
// Delete the first item in the ArrayList
list.remove(0); // removes the first item
// Update the ListView
adapter.notifyDataSetChanged();
If you are not using Strings, replace <String> with your <Object Type>

Populating ListView with ArrayAdapter force closes

I am trying to use the following code to populate a ListView using a predefined array of strings:
String[] schedule_names = getResources().getStringArray(R.array.test_schedules);
// Populate the ListView using the array of schedule names
ArrayList<String> als = new ArrayList<String>(Arrays.asList(schedule_names));
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.id.listView, als);
adapter.add("Test");
ListView listView = (ListView) findViewById(R.id.listView);
listView.setAdapter(adapter);
But it force closes unless I comment out listView.setAdapter(adapter); (which obviously means the ListView isn't populated at all). It seems the reason is a NullPointerException.
Why is this?

This line is wrong...
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.id.listView, als);
...the second parameter of the constructor should not be your ListView, it should be a layout with a TextView.
Try replacing R.id.listView with android.R.layout.simple_list_item_1

Adapt ArrayList into ListView

I have a XML File and I had parsed the data into the textView successfully now I want to bind that data into the ArrayList or List and display it in ListView.
But I don't know how to bind arraylist data into the ListView.
I have added all data into the arraylist successfully as mentioned in the below code.
List al = new ArrayList();
al.add(parser.getAttributeValue(null, "firstnames"));
Kindly please help me with the code syntax for the above issue.
Regards .
Thanks in advace

please have a look at the sample at http://codinglookseasy.blogspot.in/2012/07/android-list-view-sample.html
Instead of this
aa = new ArrayAdapter(this,
android.R.layout.simple_list_item_1, months);
setListAdapter(aa);
use this in your case
aa = new ArrayAdapter(this,
android.R.layout.simple_list_item_1, al);
setListAdapter(aa);

You need to use an Adapter to bind a List to a ListView, like this:
List<String> list = new ArrayList<String>();
// add data to list
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, list);
ListView listView = (ListView) findViewById(R.id.listView);
listView.setAdapter(adapter);
Notice that the subtype of List (which is String) matches the subtype of the ArrayAdapter (also String). The layout android.R.layout.simple_list_item_1 defines how the String is displayed in every row. You can look up the specifics of this layout in your SDK, if you want you can also use you own layout. Hope that helps, good luck learning Android!

Want to load part of an array into android ListAdapter

My code works like this to list all items in my String array - itemsarray
setListAdapter(new ArrayAdapter<String>(this, R.layout.row,
R.id.label, itemsarray));
However, I know by this call that I only want to list the first X number of items from itemsarray. How can I load only the first X items form itemsarray into the ListAdapter?

There's no way to do it automatically... you will have to do it manually. You have two alternatives:
// the easy one:
ArrayList<String> someItems = new ArrayList<String>();
for(String element : itemsarray) // add the first 5 elements
someItems.add(element);
setListAdapter(new ArrayAdapter<String>(this, R.layout.row, R.id.label, someItems));
Or you can create a subclass of ArrayAdapter and override the getCount method returning X. It will make the list think it just have X elements to show.