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
Related
ListView list = (ListView) findViewById(R.id.listView1);
ArrayAdapter<String> dataAdaptor = new ArrayAdapter<String> (this, android.R.layout.simple_list_item_1, android.R.id.text1, cars);
list.setAdapter(dataAdaptor);
I write that codes for listview but I don't know how I get data for subitem. How can I do this?
A ListView item can have it's own custom layout. When you create your adapter for the ListView you can pass in the layout id to the Adapter constructor.
If you want to show some more details like image and text or two textview then You will have to extend an Adapter and implement getView() to property set the image+text.
please check this answer with examples.
Is it possible to load all items in the adapter at once?
I am using a CursorLoader, a ListView and a Cursor adapter, the items in the the adapter are loaded with scrolling.
I know I have only few simple items (about 10) so I do not have performance problems
Thanks
Read this Populating-a-ListView-with-a-CursorAdapter or this Android Cursor Example
If you want to use an ArrayList (getted from Populating a ListView using an ArrayList):
lv = (ListView) findViewById(R.id.your_list_view_id);
// Instanciating an array list (you don't need to do this,
// you already have yours).
List<String> your_array_list = new ArrayList<String>();
your_array_list.add("foo");
your_array_list.add("bar");
// This is the array adapter, it takes the context of the activity as a
// first parameter, the type of list view as a second parameter and your
// array as a third parameter.
ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(
this,
android.R.layout.simple_list_item_1,
your_array_list );
lv.setAdapter(arrayAdapter);
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();
I'm trying to input an array into a ListView. I've gotten it to work for a spin box with this code:
Spinner spinner = (Spinner) findViewById(R.id.location_spinner);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_spinner_item, model.getLocationsArray());
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(adapter);
When I run the next block of code the program closes unexpectedly. Strangely if I remove model.getLocationsArray() it runs but the view won't update.
ListView listView = (ListView) findViewById(R.id.available_locations_list);
adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, model.getLocationsArray());
listView.setAdapter(adapter);
Thanks in advance!
model.getLocationsArray() instead this... you can use directly Arraylist object. If you have.Nullpointer Exc. because of from your EditText value cant be added to your ArrayList.
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!