I have a ListView that is populated by a news server rundown (just a list of story slugs) and an arrayAdapter to modify that ListView.
I can remove items by the 'remove(Object)' function but what if there are multiple instances of 'Object'? remove() only removed the first instance of 'Object'. I cannot remove, for example, the second 'Object' in my array adapter without removing the first one. So my question is how can i work around this?
ex : Rundown A
story 1
story 2
Break
story 3
story 4
Break
story 5
etc...
so in this example i cannot delete the Second 'Break' because remove('Break') will remove the first one. if i could removeByIndex(5), that would be perfect but....
Ive tried writing my own remove function that creates a whole new adapter with all members but the specified index. here is what i was messing around with.
public ArrayAdapter<String> removeIndex(ArrayAdapter<String> arr, int index) {
ArrayAdapter<String> temp = new ArrayAdapter<String>(arr.getContext(),R.layout.list_item);
for(int i =0 ; i<arr.getCount();i++){
if(i != index) temp.add(arr.getItem(i));
}
return temp;
}
Help or suggestions are appriciated.
Handle the collection of strings yourself with a List and pass the object into the constructor of the ArrayAdapter. This leaves you with a reference to the List so you can alter the data while allowing the adapter to manage and display as needed.
Note: When modifying the data object you must call
myAdapter.notifyDataSetChanged()
afterwards - which must also be on the UI thread. Obviously the changes to the list don't have to take place on the UI thread and should most likely not happen on the UI thread.
private ArrayList<String> mData = new ArrayList<String>();
private ArrayAdapter<String> mAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
// ...
// Code that adds the strings
// Create the list adapter
mAdapter = new ArrayAdapter<String>(myActivity.this, android.R.layout.simple_list_item_1, mData);
}
private void removeItem(int index) {
mData.removeAt(index);
myActivity.this.runOnUiThread(new Runnable() {
public void run() {
mAdapter.notifyDataSetChanged();
}
}
}
Related
I have an arrayList outside of an onClick() method. I am referring to some elements in the arrayList in my onClick() class. But when I type the name of the ArrayList and the list, it highlights in red. Both of the classes are public though.
I have tried putting the code of the arryalist and the list randomization process, but the it re randomizes every time I click something.
The part that is giving me errors is in the first case in the switch case statement, where I try to get the first position in the allImages arraylist, and the first position in the imageList List. They are in the onclick class. The arrayList and List are outside of that class.
I cannot put the arrayList and List inside of the class, because that will re randomize every time I click something. (I am trying to make a matching game)
Here is the code:
public void Random() {
Integer[] allImages = { R.drawable.cheetah, R.drawable.cheetah, R.drawable.chick, R.drawable.chick, R.drawable.fox,
R.drawable.fox, R.drawable.giraffe, R.drawable.giraffe, R.drawable.owl,
R.drawable.owl, R.drawable.panda, R.drawable.panda, R.drawable.sheep, R.drawable.sheep, R.drawable.tiger,
R.drawable.tiger};
List<Integer> imageList = Arrays.asList(allImages);
Collections.shuffle(imageList);
imageList.toArray(allImages);
}
public void onClick(View v) {
final int id = v.getId();
if (maxCounter < 2) {
switch (id) {
case R.id.one:
one.setBackgroundResource(allImages[0]); THE ALL IMAGES PART HIGHLIGHTS IN RED
unmatchedImages[maxCounter] = R.id.one;
unmatchedImages[maxCounter++] = imageList.get(0); ALSO IMAGE LIST HIGHLIGHTS IN RED
break;
//After this, i have cases for each button
}
}
else {
one.setBackgroundResource(R.drawable.qmarks);
//After this, i have a setBackgroundResource for each button
}
}
Please help. Any help is greatly appreciated.
Is your Random() should be method or class?
Base on name, which starts from uppercase (Random) it look like class.
But you added public void before name, so it's method.
I think you can move your Random() method (!) content to your Activity. Are you planning to set in Fragment or Activity?
Steps to do:
1) Move your list as field in your Activity (or fragment - I don't know what you have)
2) Shuffle list in onCreate() (or in different place but before first usage)
// 0 - Use it in your class.
// This "MainActivity" is only for example - use your name!
public class MainActivity extends AppCompatActivity {
// 1 - List of items
List<Integer> allImages = {R.drawable.cheetah, R.drawable.cheetah, R.drawable.chick,
R.drawable.chick, R.drawable.fox, R.drawable.fox, R.drawable.giraffe,
R.drawable.giraffe, R.drawable.owl, R.drawable.owl, R.drawable.panda,
R.drawable.panda, R.drawable.sheep, R.drawable.sheep, R.drawable.tiger,
R.drawable.tiger};
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// 2 - Shuffle them
Collections.shuffle(imageList);
}
.
.
.
}
The problem I see is that yes Random is public but in the OnClick() method your are trying to access a property of Random without telling who is the parent.
So instead of just using allImages and imageList.get() use Random().allImages and Random().imageList.get() Hope this helps.
I have a list of elements that is editable: I can add/delete new elements to the list. Furthermore I can duplicate each Element - duplicated elements are appended to the end of the list. Each element is displayed with a corresponding EditText where users can input quantity of the given element. The Problem: After duplicating an Element E1, editing the quantity of E1 also changes quantity of E2.
Every ListItem looks like this:
TextView(ElementTitle) / EditText(ElementQuantity)
Everything works flawlessly on lists of many elements - until I use my "duplicate" function.
I assume that the problem has something to do with the Recyclerview reusing the EditTextListeners. I am assigning these in onCreateViewHolder as described in this answer: https://stackoverflow.com/a/31860393/6551120.
I tried adding notifydatasetchanged() wherever I could imagine any value. In duplicatedSelected() I tried unregistering and clearing adapter and LayoutManager and creating a new Adapter - without any result.
This is the method that duplicates my elements (In ListActivity):
private void duplicateSelected(){
List selectedItemPositions = mAdapter.getSelectedItems();
for (int i = 0; i < selectedItemPositions.size(); i++) {
int j =(int) selectedItemPositions.get(i);
modulElements.add(modulElements.get(j));
}
mAdapter.notifyDataSetChanged();
In MyAdapter:
private class ModulElementEditTextListener implements TextWatcher {
private int position;
public void updatePosition(int position) {
this.position = position;
}
//Other Override Methods cut out for simplicity
#Override
public void afterTextChanged(Editable editable) {
updatePosition(position);
int timesMultiplied;
if(editable.toString().equals("")){
timesMultiplied=Integer.parseInt("0");
}else{
timesMultiplied = Integer.parseInt(editable.toString());
}
modulElements.get(position)
.setMultiplier(newModulElementMultiplier());
modulElements.get(position)
.getMultiplier().setTimesMultiplied(timesMultiplied);
}
}
Expected result when entering quantity for E1: Quantity for E1 changes
Actual result when entering quantity for E1: Quantity for E1 and E2 (And E3, E4,E5... when I duplicate multiple times) changes.
If I save the list of elements to a database and reopen it I can flawlessy edit quantity of E1 and it does NOT change quantity of E2 - as I would expect it to happen in the first case.
Every hint or idea welcome, thank you so much!
You must implement the cloneable interface for your data model and modify this line
modulElements.add(modulElements.get(j).clone());
Now you have different objects in the list
I am implementing a Room database (because I want to move away from Loaders) and I have a query that selects objects based on the IN operator:
#Query(SELECT * FROM table WHERE icon IN(:icons))
LiveData<List<Result>> getResults(String[] icons);
The issue is that the :icons array is generated dynamically during runtime, first I generate placeholders for it and then replace them with the values, like so:
#Override
public void onActivityCreated(#Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
String[] iconsArray = generateIconArray();
mViewModel = ViewModelProviders.of(this, new MyViewModelFactory(getActivity().getApplication(), iconsArray)).get(MyViewModel.class);
mViewModel.getResults().observe(this, new Observer<List<Result>>() {
#Override
public void onChanged(#Nullable List<Result> results) {
RecyclerView.LayoutManager layoutManager = new GridLayoutManager(getActivity(), 3);
mRecyclerView.setLayoutManager(layoutManager);
GridAdapter adapter = new GridAdapter(getActivity(), results);
mRecyclerView.setAdapter(adapter);
}
});
}
The problem is that I receive an empty RecyclerView, but when I pass an array with a single icon, the query works normally.
Is it not possible to achieve the same in Room because it checks queries during compile time?
And if not, instead of that should I just use db.query(...) in my repository constructor?
I know this sort of question was asked here, but it also says that they are working on it, and I couldn't find any signs of it.
EDIT:
In case someone stumbles upon this question, I made a small mistake while implementing this feature, the code provided in onActivityCreated actually works. It's also worth mentioning that it works with String[] and lists, but not with a single string: "ab,cd,ef".
I made a small mistake while implementing this feature, the code provided in onActivityCreated actually works. It's also worth mentioning that it works with String[] and List, but not with a single String: "ab,cd,ef", which was my mistake.
I have several items in a RecyclerView and each item has a long value saved with it. I'm using FastAdapter as the adapter for my RecyclerView.
Suppose there are 7 items in the RecyclerView with the long values: 11122, 12321, -98811, 8870, -88009, 3398, and -22113.
So, what I want to do is, I want to filter the items based on the above given long values using this logic:
if (l <= 1000) {
// show items with long value <=1000
} else if (l > 1000) {
// show items with long value >1000
}
I tried various things, but nothing worked out.
UPDATE 1: Items here are a sort of different data stored in CardView and then shown in RecyclerView. Each card contains different data, one of which are the above given long values. I want to filter the data based on these long values stored in each card based on the logic given above.
Please help me with this issue and suggest some algorithm or code with which I can achieve this.
With the amount of information given I can only suppose l is a foreign selector value which controls the items to be displayed inside the RecyclerView. Comment below if this is not the case, I will try to correct my answer.
I recommend implementing a custom ViewAdapter, sending in the list of items and the selector variable l using respective methods:
public class ItemsAdapter extends
RecyclerView.Adapter<ItemsAdapter.ItemViewHolder> {
private List<Long> mItemList;
private List<Long> mDisplayItems;
private boolean mAboveThousand = true;
public void setItemList(List<Long> list) {
mItemList = list;
updateDisplayItems();
}
public void setSelectionType(boolean aboveThousand) {
mAboveThousand = aboveThousand;
updateDisplayItems();
}
private updateDisplayItems() {
mDisplayItems.clear();
for(Long item: mItemList) {
if(/*check your contition*/) {
mDisplayItems.add(item);
}
}
notifyDataSetChanged(); //important
}
...
// Rest of implementation
}
Also, I have never used FastAdapter, but I suppose there must be some methods to override if you extend its class.
Update
Since, you are facing problems understanding the basics of using a ViewAdapter, I would recommend learning and implementing a custom ViewAdapter before using any library. Here's a extensive tutorial for how to implement ViewAdapter for RecyclerView.
Now, after you have implemented the ViewAdapter you can use my piece of code to filter out cards. Basically, what the code is doing is saving a list of all the required data inside mItemList, while mDisplayList is a list storing the items to be displayed, which is updated every-time mAboveThousand, which stores the user preference of above or below 1000, is set. Now this mDisplayList must be used to inflate data inside the RecyclerView.
Even your very basic code there would work. You can count the number of items in that range and return the number in that range. I suggest you try to do this without FastAdapter because the core concept of parsing the data based on a filter value is rightly perfectly solid. You can iterate the loop and count them, and you can iterate the loop and return the nth item.
If you do want to keep using FastAdapter, it has a built-in filter functionality (see point number 5 in the README of the project. Note that the filter method should be called after withFilterPredicate and not before as shown there).
EDIT - after you pointed out that I misunderstood you before - here is my updated proposed instructions:
You need to resolve the logics of which set you want to display (using the checkboxes in the dialog you mentioned in the comment) and pass that information onto the filter, for example:
boolean displayUnderThreshold = //put the logic here - true if you want <1000
fastAdapter.filter(Boolean.toString(displayUnderThreshold));
And where you set the adapter (before the above line is called) have:
final long threshold = 1000;
fastAdapter.withFilterPredicate(new IItemAdapter.Predicate<GRModeClass>() {
#Override
public boolean filter(GRModeClass item, CharSequence constraint) {
boolean displayUnderThreshold = new Boolean(constraint.toString());
return (displayUnderThreshold ^ (item.l<threshold)); //false to remove from list
}
});
Old answer From when I thought you wanted to filter the items according to their ms long values, using an external l long indicator:
In your code, assuming your app does get to the if you mentioned in the question when it should - remove the fastItemAdapter.clear(); and instead of the for loop with the if inside it write
fastItemAdapter.filter(Long.toString(l));
and somewhere before that, preferably where you set the adapter (most likely in the onCreate of MainActivity) add the following:
final long threshold = 1000;
fastAdapter.withFilterPredicate(new IItemAdapter.Predicate<GRModeClass>() {
#Override
public boolean filter(GRModeClass item, CharSequence constraint) {
long indicator = new Long(constraint.toString());
return (item.ms<threshold && indicator>=threshold) || (item.ms>=threshold && indicator<threshold) ;
}
});
(Assuming here that GRModeClass is your items' class and that the long ms is the long you referred to that should determine whether the )
I guess your class is like
public Class ListItem {
// .. Some other attributes
public long l;
}
Now I hope you've some function which is called when you're putting a filter in your RecyclerView. Let the function name is toggleFilter.
public void toggleFilter(long l) {
if(l <= 1000) {
fastAdapter.withFilterPredicate(new IItemAdapter.Predicate<Item>() {
#Override
public boolean filter(ListItem item, CharSequence constraint) {
if(item.l <= 1000) return true;
else return false;
}
});
} else if (l > 1000) {
fastAdapter.withFilterPredicate(new IItemAdapter.Predicate<Item>() {
#Override
public boolean filter(ListItem item, CharSequence constraint) {
if(item.l > 1000) return true;
else return false;
}
});
}
// Finally call notifyDataSetChanged
fastAdapter.notifyDataSetChanged();
}
You can filter while fetching from firebase.
l <= 1000
firebaseDatabase.child(key).orderByChild("long_value_key_in_firebase").endAt(1000);
l > 1000
firebaseDatabase.child(key).orderByChild("long_value_key_in_firebase").startAt(1000);
In the below code, where the item’s position and title is getting saved in list_items works fine if list_items and items are ArrayList. For ex;
ArrayList.add(ArrayList.get(position));
But I am trying to use listview:
ArrayList.add(Listview.get(position));
Below is my code
final Listadapter Adapter =new Listadapter(this,packageList1,packageManager);
items.setAdapter(Adapter);
items.setChoiceMode(apps.CHOICE_MODE_MULTIPLE_MODAL);
items.setMultiChoiceModeListener(new AbsListView.MultiChoiceModeListener()
{
#Override
public void onItemCheckedStateChanged(ActionMode mode, int position, long id, boolean checked)
{
count = count +1;
mode.setTitle(count + "items selected"); //problem resides in the below line
list_items.add(items.get(position));
}
In the above code, on selecting an item from listview I am trying to save it in an Arraylist i.e list_items which could be used in onActionItemClicked method for further action on that respective item.
Any ideas on how to solve or find a workaround to use a listview in the above situation?