Develop Reference

Android - Select all items using SelectionTracker

I'm using SelectionTracker form the support-library-v28
It works great, just as expected.
Only thing I need, is to enable Select All feature (using the ToolBar)
Looking at the API, I see that there is one way to select all, but that one requires creating Iterable<Long> with all the values, meaning, create an array which hold Long values from 1 to datasource.size()
Is there any simpler way to select all the items in my datasource?

Seeing as I've recently had to set up the same sort of functionality, I thought I'd share my approach. Using the setItemsSelected(Iterable<K> keys, boolean selected) method really isn't as complex as it seems.
Yes, you will need to pass in an iterable. What I did was, loop through my data and store the index of each item as a 'long' inside of an arrayList().
EX:
yourData.forEachWithIndex { i, item ->
//Be sure to start at one, just plus one
someOtherTempArray.add(i.toLong() + 1)
}
Then I created a method that makes it easy to 'trigger' the select all functionality:
EX:
private fun startHandler(isChecked: Boolean){
val handler = android.os.Handler(Looper.getMainLooper())
val runnable = Runnable {
kotlin.run {
mTracker!!.setItemsSelected(someOtherTempArray.asIterable(),
isChecked)
}
}
handler.post(runnable)
}
The 'isChecked' parameter, which will essentially determine if we want to select all or deselect all.
Note that I am simply using my arrayList of 'keys' (for me this is just the index of the item. However, this may differ depending on how you have your ItemDetails Builder set up) and calling the Kotlin .asIterable() function to turn it into an iterable.
I have also placed the call to setItemsSelected() inside of a handler to force the selection to take place on the UI thread.
Now whenever you want to select/deselect all, you can call the startHandler(true)!

Adding and Deleting between two seperate Array ListViews

I want to create a custom ListView.
Initially, the custom ListView has one array of data, but when user taps one of the list items, it's then removed from current array and added to another. If the user taps on the second array, the list item is then added back over into the first array.
Please suggest how to apply logic to do this.
Updates : I wants to use only one listview/recyclerview.
Following are screen shots..

Regarding the object switch - this is a simple transfer between lists, , just know beforehand if the insertion and removal is index based, e.g:
contacts.add(iLocation, ContactObject);
favorites.remove(iOtherLocation);
Regarding the ListView stuff, I would suggest converting to RecyclerView, let's build a general scenario:
You have a screen (Activity or Fragment) that holds one list (the implementation can be ListView or Recycler), and another screen that holds the other list.
In both of your lists you have adapters in which you implement the logic for the clicks on the objects in the lists.
The click transfers the object, either directly to the other list, OR to a temporary Object holder (because you might need it for other stuff), in which case you will need to pull that object from the other view, either way you remove it from the current one.
you switch to the other view, and refresh it.
An easy way to go -
Assuming the screens are the same, use only one Activity, holding a single RecyclerView, and handle 2 adapters, each for every list, the adapters allow you to handle the clicks easily, with an index for the object clicked, the click executes the info swap action,the Activity handles the visual swap Action.
a very general example would be:
//init everything obviously ;)
List<ContactObject> contacts;
List<ContactObject> favoritesContacts;
//the AdapteListener is an interface declared inside the adapter
mContactsRecyclerAdapter = new ContactsRecyclerAdapter(this, contacts,new ContactsRecyclerAdapter.AdapterListener()
{
#Override
public void cellClicked(int iIndex, ContactObject object)
{
favoritesContacts.add(iIndex, ContactObject);
contacts.remove(iIndex);
mContactsRecyclerAdapter.notifyDataSetChanged();
mFavoritesRecyclerAdapter.notifyDataSetChanged();
mRecyclerView.swapAdapter(mFavoritesRecyclerAdapter, false);
}
});
And vice-versa for the other adapter.
Hope this helps, comment if you have problems and I'll update.

Please implements with custom view extend with Linearlayout
Custom view has 2 child Linearlayout in which will add with this custom view
First time add all the element in first Linearlayout and based on user action please remove from first Linearlayout and add it in another layout

Wait until Spinner is refreshed

I have a kind of form with 3 Spinners. The content of 2 Spinners (minorSpinner) depends on the selection of the first one (mainSpinner). To be more precise, I set the content of those 2 minorSpinner in the mainSpinner's onItemSelected listener.
The form can be saved and load back again.
The problem is:
When I am trying to load the form, first I set the mainSpinner and then minerSpinners.
Like:
mainSpinner.setSelection(value);
minorSpinner1.setSelection(value1);
minorSpinner2.setSelection(value2);
Unfortunatelly the minorSpinners are not ready in time. Maybe because their values are set in the UI Thread?
Question:
how to wait until they are ready?
What I tried:
runOnUIThread(){
mainSpinner.setSelection(value);
minorSpinner1.setSelection(value1);
minorSpinner2.setSelection(value2);
}
but ti does not work:(
Any idea?

how to wait until they are ready?
So my first idea is to register OnItemSelectedListener() for all Spinners.
Then create two boolean variables for example isSpinnerOneSelected, isSpinnerTwoSelected and when you'll select item from Spinner, assign variable to true.
Then create some Thread (with Handler) that will control your states. If both variables are assigned to true, just make action with third Spinner.
If you don't know how to use Handler, look at:
How to run a Runnable thread in Android?

Displaying an array of objects, one at a time through a single dialog... instead of several dialogs

In my application I have a list of questions stored in an ArrayList, and I want to display a dialog that shows one question, and then continues to the next one after the question is answered. The way that I'm currently doing it (iterating through a loop) hasn't been working because it just layers all of the dialogs on top of one another all at once which causes a host of other issues. What I'm looking for is a way to still iterate through the questions, but just change the layout of the dialog each time until it has finished each question in the list. Can anyone give me a good pointer for how to get this going?

You can make a function that takes title and message as parameters and shows a dialog.
showDialog(String title, String message){ // Show dialog code here}
Within that dialog's answer button's listener call another function (showQuestion(currentQuestion)) that iterates the arrayList till it is over
int currentQuestion=0;
ArrayList<QuestionObject> questionList;
showQuestion(int i){
if(i<questionList.size()){
showDialog(questionList.get(i).getTitle,questionList.get(i).getMessage);
currentQuestion++;
}else{
//quiz is over
}
}

I assume you mean that you just want to change 1 single layout(created within XML i.e main.xml). In order to do this, make sure that the class your working on is pointing to that layout. From there (assuming your using an Event listener for when the user submits an answer) you can change do as you want by the following:
TextView txt = (TextView) findViewById(R.id.textView); // references the txt XML element
and in your Event listener, if the answer is correct then change(Have i be a global variable thats initially set to 0).
if(i<arrayList.size()){
txt.setText(arrayList.get(++i));
}else{
txt.setText("You Finished");
}
From there, in the else statement, you can change arrayLists and reset i to 0;

If you are trying to use the positive, neutral, and negative buttons; then you may have problems with multiple dialogs. Try defining a customized layout with your own TextViews, ListViews, and Buttons. You can implement listeners and everything else like a regular layout. Then just pass your customized layout to the dialog through AlertDialog.Builder.setView().
PS If you include code examples of what you are currently doing we can provided answers that are less vague.

How do I display consecutive AlertDialogs in Android?

I'm trying to port one of my iPhone apps over to the Android. It was all going along swimmingly until I came to AlertDialogs. In the iPhone app, sometimes there will be more than one alert to pass to the user. When this happens, the first alert dialog will come up, and when they click it away the next one will come up.
I can't seem to get more than one dialog box to come up like that in Android. Is it possible to display back to back AlertDialogs where a second one pops up as soon as the first is finished?

You execute 2 consecutive call to 'showDialog()' after eachother and the second will show after the 1st was dismissed:
showDialog(FIRST_DIALOG_ID);
showDialog(SECOND_DIALOG_ID);
Ofcourse you also have to implement onCreateDialog().

If you feel that you will be having multiple dialogs, one after another, you could create a custom class that holds all of the information for the alert, such as the title, text, icon, etc. From there, create an arraylist to store the custom class objects. When you are done with your first dialog, remove it from the arraylist, then check to see if there are any remaining dialogs that need to be presented.
The only issue you'll run into is that it will be much more difficult if you want to have different conditions in your Confirm and Cancel options.
public class DialogObject(){
String title;
String body;
String iconName; // or just an Image asset
}
ArrayList<DialogObject> dialogList = new ArrayList<>();
When a dialog is required, add it to the list if there is a dialog already on screen
dialogList.add(new DialogObject(param1, param2, param3));
This may not be the best way, but it is an option. The ArrayList will need to be in a separate class itself so you don't lose the data when moving from screen to screen.
For example - Note the "static" keyword.
public class DialogHolder(){
public static ArrayList<DialogObject> = new ArrayList<>();
}