I want to show an empty list view, which is then populated by user input. I have the UI flow working, and I populate a list of my custom objects after the user enters some information via a view which is invoked through setContentView (i.e. no a new Activity).
I take the input and add it to a list, which I want to be summarised on the ListView. However, whenever I add to the list and/or the ArrayAdapter and call adapter.notifyDataSetChanged() it does not do what I want. The ListView is still empty. Argh! It's driving me insane!
#Override
public void onCreate(Bundle blah) {
ListView listView = (ListView) findViewById(R.id.results_list);
listView.setAdapter(new ArrayAdapter(this, android.R.layout.simple_list_item_1, list));
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.mnu_add:
final Activity act = this;
setContentView(R.layout.record_details);// the sub-view that takes the user input
// the button on the form to 'add' details:-
((Button) findViewById(R.id.recored_details_add_btn))
.setOnClickListener(
new OnClickListener() {
public void onClick(View v) {
// get input from widgets
list.add(someObject);
((ArrayAdapter<Object>) listView.getAdapter()).notifyDataSetChanged();
setContentView(R.layout.list_view);
}
}
);
((ArrayAdapter<Object>) listView.getAdapter()).notifyDataSetChanged();
break;
}
return true;
}
Please, save me from my misery and inform me of my stupidty?
Thanks in advance.
public void onClick(View v) {
// get input from widgets
list.add(someObject);
((ArrayAdapter<Object>) listView.getAdapter()).notifyDataSetChanged();
setContentView(R.layout.list_view);
Is it possible that this setContentView in the onClick handler is creating a new instance of the list view widget (with no adapter) or reinitializing the list view (clearing the adapter)?
Try putting something in the list initially in onCreate and then see if it disappears when you hit the button.
I haven't seen any code (although I'm a relative newbie) that switches views within the activity's lifetime to bring up essentially bring up different pages - most use a separate activity.
Edit:
OP asks:
Thanks...So how can I get what I want? The list I'm backing the adapter with is static; should I just use activities instead and rely on onCreate loading from the static field?
Some options:
Use separate activities
Re-associate the adapter (call setAdapter again) - probably a bad idea
Declare both layouts in the same file. You'll hide one and unhide the other to switch between views rather can calling setContentView. This is similar to how ListView layout works (one for when the list is empty and one for when it is not). I think I've seen an example of this somewhere on the net, but I don't have a reference right now.
You could relaunch the same activity by using Intent.FLAG_ACTIVITY_SINGLE_TOP flag while creating the intent and override the onNewIntent() method.
Inside the onNewIntent() you create the adapter with updated data and call setAdapter.
I think this will give you the intended behaviour.
Related
This might sound a bit convoluted.
I have roughly 15 Spinners in one activity and made a distinct method for each of these spinners. I then initiate the methods in the onCreate method.
Method example:
//Relative Position Spinner
public void relativePositionSpinner() {
Spinner relativePositionSpinner = (Spinner) findViewById(R.id.spinner_relativePosition);
ArrayAdapter relativePositionAdapter = ArrayAdapter.createFromResource(this, R.array.relativePosition, R.layout.spinner_item);
relativePositionSpinner.setAdapter(relativePositionAdapter);
//what happens when selected
relativePositionSpinner.setOnItemSelectedListener(this);
}
OnCreate Method:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_new_hand);
//initiate all Spinners
relativePositionSpinner();
absolutePositionSpinner();
etc.
Now what I want is to send the data of each Spinner to another Activity with the click of a Button. I know that I can do this with an intent and using putExtra in the Button method like this:
public void openHandSummary() {
//Find the Button that gives option to enter new hand
Button handInputButton = (Button) findViewById(R.id.hand_input_button);
//set a click listener on Hand Analyzer Button
handInputButton.setOnClickListener(new View.OnClickListener() {
//below code will be executed when the new Hand Button is clicked
#Override
public void onClick(View view) {
Intent handSummaryIntent = new Intent(NewHandActivity.this, HandSummaryActivity.class);
handSummaryIntent.putExtra("RelPosString", WHATTOENTERHERE??)
startActivity(handSummaryIntent);
}
});
}
However I do not know how to retrieve the value/variable out of my Spinners to put them into the Button/intent method? Because if I make a String in the Spinner method, then I can't access this in the Button method.
So I feel like I have too many methods? So is there a way to pass data from one method to another method, or do I have to cancel some methods? What would be the easiest way to set this up?
I also made an onItemSelected to make some toasts, which worked. Can I use OnItemSelected somehow to create variables or initiate a data transfer to another Activity?
#Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
TextView myText = (TextView) view;
switch (parent.getId()) {
case R.id.spinner_relativePosition:
makeText(NewHandActivity.this, "Relative Position is " + myText.getText(), Toast.LENGTH_SHORT).show();
break;
case R.id.spinner_absolutePosition:
makeText(NewHandActivity.this, "Absolute Position is " + myText.getText(), Toast.LENGTH_SHORT).show();
break;
I'm very new to coding, and I just can't figure out the logic how I get the Spinner methods, Button/iniate method and OnItemSelected method to work together and exchange variables. Would appreciate if someone can point me in the right direction. Have already browsed the internet a day or so to find an answer, with no success.
I like your idea of separating out the code to create each spinner into its own method. However, if you are copying and pasting the whole method and making a few changes, you should step back and think about how you can do it even more easily. Often the changes you make after copy and paste give a hint that you should add some parameters to the method. If you do it correctly, you can write just a single method and then copy and paste the method call instead of the entire method and then make appropriate changes to the arguments.
As for your actual question, you are making this much more complicated than necessary. Specifically, you do not need to setOnItemSelectedListener() on any of the Spinners. Instead, the OnClickListener for the button should just get the selected item from each spinner and send it to the new activity in the Intent.
I have two listview, like listview_1 and listview_2. I wanna refresh the listview_2 while listview_1 is refreshed.
My code like this:
public void updateTwoListView() {
listview_1.getAdapter().notifyDataSetChanged();
listview_2.getAdapter().notifyDataSetChanged();
}
But it don't work, listview_1 can refresh but the listview_2 can't.
And at that moment what I found is that listview_1 was on focus.
And then I tried to set focus to other views before ran the method, both of them didn't refresh. It likes to refresh a listview only if the listview has focus.
What's more I found that when I called the method to refresh, listview_2 didn't, and then I set focus to listview_2, refreshed itself!
So, What all I want to ask is:
How to refresh two listview at one moment in Android?
What's more code:
//init two listview there
public void init() {
listview_1 = (ListView)findViewById(R.id.listView1);
listview_2 = (ListView)findViewById(R.id.listView2);
adapter1 = new MyListViewAdapter(mContext);
adapter2 = new MyListViewAdapter(mContext); //I have tried use different adapter, that also didn't work.
listview_1.setAdapter(adapter1);
listView_2.setAdapter(adapter2);
}
the real code of upside snippet is:
public void updateTwoListView(int currentPosition) {
adapter1.updateCurPos(currentPosition);
adapter2.updateCurPos(currentPosition);
}
and in MyListViewAdapter.java:
public void updateCurPos(int currentPosition) {
mCurrentPos = currentPosition;
notifyDataSetChanged();
}
And I will call method like listViewManager.updateTwoListView(1) outside to refresh.
Any reply is appreciated.
You have called listview_1 twice. Just change one of them to listview_2 as below:
public void updateTwoListView() {
listview_1.getAdapter().notifyDataSetChanged();
listview_2.getAdapter().notifyDataSetChanged();
}
It seems the problem of your code is that you call getAdapter().
Sets the data behind this ListView. The adapter passed to this method may be wrapped by a WrapperListAdapter, depending on the ListView features currently in use. For instance, adding headers and/or footers will cause the adapter to be wrapped.
Source: http://developer.android.com/reference/android/widget/ListView.html#setAdapter(android.widget.ListAdapter)
The solution is save your Adapter as member variable in your activity and call the notifyDataSetChanged()from there.
See more on this question's answer: https://stackoverflow.com/a/31893525/2742759
I'm working on a fragment that contains a listview (this fragment is PlaceHolderFragment generated when create activity). I extends ArrayAdapter to make my custom adapter and fill my listview with this adapter.
One important thing is in one row of listview, there are 2 buttons: first is the enable/disable button to change status of an user (when user's status is active then it's disable, otherwise enable), second is the delete button (to delete user). So I have to implement OnClickListener for this 2 buttons in method getView() of adapter
When click either buttons, it will send request to server and manipulate database (change user's status or delete user from database). The thing is when I click enable button (for example), it is success and user's status in database is changed, or when I click delete button, user will be delete from database successfully
BUT after I click that button, it's state does not changed (I mean if user is enabled, now the button must change to disable, or if user is deleted, that row must be remove from screen). I have to reload this fragment by hand (switch to other fragment and then come back)
The question is how can I reload activity (I already implement onResume to load all data to adapter, so if I can make this method onResume of fragment run, it will work as my expectation), or at least how can I reload the listview to update new data?
Note: notifyDataSetChanged() DOES NOT work because the data in adapter actually doesn't change yet, only data on server are changed
Note 2: if you need me to post my code, please comment and I will edit my post, because I think my code is long
Thank you and best regards!
EDIT 1
I've posted my solution in the answer below, it fix the problem but I have to say that this is a very very BAD practice in android. For example, when you want to delete an item with this approach, you may want to put a AlertDialog for user to confirm, but AlertDialog can only show in Activity (or Fragment), it can't be show from Adapter. So instead, you should use some different methods such as ContextMenu or CustomDialog.
After couple of weeks searching google and try different methods, I finally found a way to archive what I want, and it's very simple. I post my answer here for anyone facing this problem like me in the future
public class CustomAdapter extends ArrayAdapter<YourClass> {
private List<YourClass> items;
private CustomAdapter adapter;
private Context context;
private Button button;
private YourClass item;
public CustomAdapter(Context context, List<YourClass> items) {
super(context, R.layout.custom_list_item, items);
this.items = items;
this.context = context;
this.adapter = this; //This is an important line, you need this line to keep track the adapter variable
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
if (v == null) {
LayoutInflater li = LayoutInflater.from(getContext());
v = li.inflate(R.layout.custom_list_item, null);
}
item = items.get(position);
button = (Button) v.findViewById(R.id.button); //Find the button
button.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View view) {
//Do something inside here like update, remove your item...
//But the important is
items.remove(item); //Actually change your list of items here
adapter.notifyDataSetChanged(); //notify for change
}
});
}
return v;
}
That's it, all you need to implement when you need the listview to reload in case you need to implement OnClick inside the adapter. Hope you guy find it easier than me when you face this problem
What I understand from your question that you want to refresh the list data when click on one of the button as you need.
Now You should call notifydataset change rather reloading the activity again.
For this you need to change the array that yu are using for the adapter(Don't change the array object just the Item of the array)
like arraylst.get(index).activ=true etc etc and then call notifiydataset change.
I created an expandable listview based on this link. Its just working fine. Now what i want is
1) How to make a childview to link another sub-child view
2) The sub- child view should be open as a new list view on the window(Right side of the view) is my expected layout. I googled but couldn't find how to achieve this. Please help me in achieving this. Thanks in advance.
You'll need to specify and handle onClick event of ListView row items.
Then you'll open a new Activity, based on the item clicked.
Parameters for new activity are supplied through intent extras, the new activity can use these values to get data from cloud or process the values to show certain results.
I've used CustomAdapter class several times to handle this scenario.
class Ocl implements OnClickListener{
#Override
public void onClick(View v) {
Intent intDetail = new Intent(getActivity(), PartDetail.class);
intDetail.putExtra(_ID, mParts[position].getSPr());
intDetail.putExtra(_LOT, mParts[position].getLotID());
intDetail.putExtra(_QTY, mParts[position].getQty());
intDetail.putExtra(_UID, mParts[position].getPartID());
startActivity(intDetail);
}
}
So, do you want your first child to expand into another ListView? Or maybe just open another Activity/Fragment that contains the matching ListView?
In case you want to the the first, you could design a CustomLayout for the Childview, which on OnClick expands, and changes its content to a specific ListView.
Otherwise you would just open up another ListView with data depending on Which Child in First List was Clicked.
Well, i am using some Like that to enlarge ChildViews on Click to show me detailed information.
Im using a Class to wrap my Data named Row. These Rows indicate if they are clickable and if so, the ListView will allow clicks on the rows. A Click will then be handled by the Class itself, making the displayed Text longer(more Detailed). And in order to relayout the items, you need to call notifyDataSetChanged.
#Override
public void onClick(Context context, MyExpandableListAdapter mela) {
this.setBig(!isBig());
mela.notifyDataSetChanged();
}
So, i would handle the row state (expanded/normal) in the getView Method of parents Adapter, to decide which childLayout i inflate.
would looke something like this
public View getView (args...) {
Object data = getItem(position);
if (data.isExpanded()) {
//inflate ListView Layout, create Addapter fill it....
} else {
//show some title or whatever to identify row.
}
}
i want to show this array as a listview in a new screen when a button is clicked.
ArrayList<String> favorite = new ArrayList<String>();
this ListView is a small part of my class. i cant seem to figure out how to implement it with my code (i can figure out how to create a listview in a separate application, and set the onitemclicklistner just for that listview)
i want to display that listview when.
case R.id.ShowFavButton:
Your question isn't entirely clear.... but you would build a separate Activity, possibly subclassing ListActivity (documentation here), and then load it when you click on the button. If your Activity was named FavoritesActivity, it would be something like this:
Button fav = (Button)findViewById(R.id.ShowFavButton);
fav.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
startActivity(new Intent(FirstActivity.this, FavoritesActivity.class));
}
});
If you want to return something from your FavoritesActivity to your FirstActivity (or whatever it is called), you can use startActivityForResult instead of just startActivity.