I'm making a to-do list app and after user presses the button I create a new GridLayout(and all the data about time and name of the task inside of it) and add it into my RelativeLayout. How do I save those GridLayouts in UI so after the activity is destroyed and launched again those layouts are there.
After pressing the button I trigger the Create Activity method
public void CreateActivity(String name,int hours, int minutes,int i)
{
RelativeLayout.LayoutParams relparams= new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT,RelativeLayout.LayoutParams.WRAP_CONTENT);
relparams.addRule(RelativeLayout.BELOW,i);
relparams.setMargins(0,50,0,100);
Glayouts.add(new GridLayout(this));
Glayouts.get(i+1).setBackgroundColor(Color.GRAY);
Glayouts.get(i+1).setMinimumWidth(relative.getWidth());
Glayouts.get(i+1).setId(i+1);
Glayouts.get(i+1).setPadding(10,0,0,0);
GridLayout.LayoutParams namee = new GridLayout.LayoutParams();
namee.columnSpec = GridLayout.spec(0);
namee.rowSpec = GridLayout.spec(0);
namee.setGravity(Gravity.LEFT);
final TextView Actname = new TextView(this);
Actname.setText(name);
GridLayout.LayoutParams checkbox = new GridLayout.LayoutParams();
checkbox.columnSpec = GridLayout.spec(1);
checkbox.rowSpec = GridLayout.spec(0);
checkbox.setGravity(Gravity.RIGHT);
CheckBox check = new CheckBox(this);
// ADDING TO LAYOUT
Glayouts.get(i+1).addView(Actname,namee);
Glayouts.get(i+1).addView(check,checkbox);
relative.addView(Glayouts.get(i+1),relparams);
Theoretically when you extends View, then you can also override onSaveInstanceState and onRestoreInstanceState methods, where you must provide your own SavedState class that typically extends BaseSavedState. You can find info on that here
In your case, your layout is dynamic, therefore this doesn't really work. To tell you the truth, your layout probably shouldn't be constructed this way, you should be rendering the grid using a RecyclerView based on a "model" that describes this layout, render the items of the grid via the RecyclerView.Adapter, and you should persist either the "model", or the data you use to construct this model along with the user-inputted state so that you can re-construct the model that will be rendered via your RecyclerView.
You can read more about RecyclerView here.
You can read more about data persistence here.
You can read about using onSaveInstanceState to save data in Activities/Fragments across config change and process death (but not finishing then restarting the app) here.
You can’t. The best way to save state is to use some persistence mechanism, for example database (I’d recommend Room as it is officially supported by Google).
After clicking a button, you should put all the needed information (name, hours, minutes) in the database and when Activity is created, you can read all persisted data and - basing on it - create all needed layouts again.
Another option is storing data in SharedPreferences - it is much easier to setup, so you can also start with this solution. Please note, I'm suggesting it as a first step in the world of persistency in Android, not as a preferred solution for storing data.
Related
In my activity I try to call a method from a class but it's not getting the right values.
This is ActivityTwo:
int id = intent.getIntExtra("id", 0);
LayoutInflater inflater = getLayoutInflater();
View mainActivity = inflater.inflate(R.layout.activity_main, null);
LinearLayout eventsLayout = mainActivity.findViewById(R.id.eventsLayout);
Log.d("ACTIVITY_eventlayout", String.valueOf(eventsLayout)); // gives the layout perfectly
Event.RemoveSpecific(eventsLayout, id);
finish();
This is the class(Event) with the method:
public static void RemoveSpecific(LinearLayout layout, int id){
View event = layout.findViewById(id);
Log.d("INSIDE_removespecific", String.valueOf(event));// event is null
layout.removeView(event);
}
And in my MainActivity it's working fine:
LinearLayout eventsLayout = findViewById(R.id.eventsLayout);
View event = eventsLayout.findViewById(id);
//Log.d("MAIN_event", String.valueOf(event1)); // gives it perfectly
eventsLayout.removeView(event);
I also add this view in my MainActivity and use .setId(id) to give it the right id. So my question is, why is the View in my class method null, while I pass the right LinearLayout from my activityTwo?
Where does the id come from?
I have the Event class which contains an id, name, date, & description. This class also has a static ArrayList called eventsList. Whenever the user creates a new reminder I create a new Event using my class and giving it an id as Event.eventsList().size() (after adding it to my eventsList [so the first event id is always 1]), then I create a new View and pass the recently created Event details and use setId() to give it an id [1]. Then in this View I have a button which has an onClickListener which passes the given View id and the LinearLayout (where the View was added) to my Event.removeSpecific() method.
App flow:
The user clicks a button in MainActivity to create an event, then the button click then use startActivityForResult() with an intent to open a new Activity where the user puts in a name,description and date for the event, then I create an intent with putExtra() methods and then use setResult(RESULT_OK, resultintent) to send the data back to MainActivity. Now when the MainActivity gets the data back I use .getStringExtra() to create a new Event object with the data and add it to may Event.eventsList ArrayList, then I use the following:
LayoutInflater inflater = getLayoutInflater();
View event_Exmaple = inflater.inflate(R.layout.event_example, null);
and set the textView's with the data I got, and use event_example.setId(Event.eventsList.size()) to give it an id.
After that I add this to my LinearLayout (which I declared already in the MainActivity):
eventsLayout.addView(event_example)
Now I mentioned that the Event class has a date field. I use that to set up an alarm with AlarmManager. With the AlarmManager I send the current Event object's data through the intent and when the user gets the notification it opens up a new Activity which gets the given Event object data (with intent.putExtra()'s) and that's the part where the user clicks on a Button. I want to remove the given Event object's View from my LinearLayout in the MainActivity XML.
well since you didn't share where the id value come from (from where the intent gets its data/how you put the values in it/where the values come from), I assumed this solution :
whenever I use a 'switch' statement with View Ids it tells me a very important warning which is
Resource IDs will be non-final in Android Gradle Plugin version 5.0, avoid using them in switch case statements
that means that view Ids doesn't have a stable id in some cases that you shouldn't consider them to be final.
I guess in your case when you get an id to your event view and then inflate the layout view, the inflate procedure involve changing the 'int' id value of the event view so whenever you query the old id it returns null since the event view inside the inflated layout view now has a new 'int' id value.
I don't know why it works in main activity since you didn't share full code where you get the id from.
so I guess the only solution is that you should find a way to get a fresh copy of the id after you inflate the view you want to work on in the method.
Update
the problem is with this block of code
View mainActivity = inflater.inflate(R.layout.activity_main, null);
everytime you inflate a new layout view thinking that you have the one used by main activity back there but instead you're creating an entirely new one with new views and new Id's.
that would be why you could get the view in main activity but you can't get it from a newly inflated view.
Update
if you need to remove this item using the id and have a static array stored in the view custom class, call a getter on the static array and remove the item from it instead of trying to remove the view itself.
a better implementation of the whole situation is to store these events in a database using room instead of the static array, that way you could delete/add/edit any event anytime with just one line of code, if you're willing to do this you can start by reading the developers documentation of room.
I am programming an app for Android. I uploaded it to GitHub: app
I have a ViewPager (MainActivity.java) controlling two Fragments. On the first Fragment (FirstFragment.java) you can add People (People.java) which appears on the RecyclerView (also on FirstFragment.java). When you click one of the list items on the RecyclerView its details (name and id) appear on the second fragment (SecondFragment.java). The SecondFragment.java also contains a button you can delete the selected People with.
To store the People objects I used a List of People and managed it with the methods in PeopleLab.java. The program was working fine: I could add/remove People objects to the list and it appeared on the RecyclerView fine.
After that, I decided to replace the List with a database. It only meant creating the database (the 3 files in database folder) and editing the already existing and two new methods in PeopleLab.java. The other files remained untouched.
The database is working as expected (checked it with sqlite3), I can add/remove People like before and the queries work. My only problem is that the changes don't appear on the RecyclerView. But if I close and reopen the app, the changes appear.
It's like the RecyclerView doesn't care about the database in runtime, only do when the app starts (or closes, not sure).
Do you have any idea what could cause the problem? My only guess is I miss something about how Android apps handle databases.
P.S.: sorry for my English.
You do call notifyDataSetChanged() on the adapter but you don't provide any new data for that adapter.
In your FirstFragment :
private void updateUI() {
PeopleLab peopleLab = PeopleLab.get(getActivity());
List<People> peoples = peopleLab.getPeople();
if(mAdapter == null) {
mAdapter = new PeopleAdapter(peoples);
mRecyclerView.setAdapter(mAdapter);
} else {
// You actually have to change your dataset
mAdapter.changeDataSet(peoples);
}
}
And in your Adapter :
public void changeDataSet(List<People> people) {
this.mPeoples = people;
notifyDataSetChanged();
}
This some brutal way to do it though.
It would be better to notify your adapter on insertion / removal calling notifyItemInserted(int itemPosition) or notifyItemRemoved(int itemPosition). (And refreshing your dataset, by the way)
It will not work automatically.You can either use to notify the adapter the underlying data has been changed so that adapter can fetch and reload the data.It can be done using adapter.notifyDataSetChanged()
Or use can use CursorLoader to achieve the same
I am creating a feature inside my Android app that will allow users to see their 6 last used apps in a gridview with only the application image. So far I have tried this:
//Load recent used apps
ActivityManager result = (ActivityManager)this.getSystemService(Context.ACTIVITY_SERVICE);
ArrayList<RecentTaskInfo> apps = (ArrayList<RecentTaskInfo>) result.getRecentTasks(10, ActivityManager.RECENT_WITH_EXCLUDED);
ArrayAdapter adapter = new ArrayAdapter(MainActivity.this,
android.R.layout.simple_list_item_1, apps);
recentappsGridView.setAdapter(adapter);
But this only shows a lot of text in each row and column. How can I fix this/make it happen? Please note that I am already using a ListView within the same activity with a method for its click events.
Create a subclass of ArrayAdapter. Override getView(). Set up your cells to be images, not TextView. Use resolveActivityInfo() on the Intent you get from baseIntent in the RecentTaskInfo to get an ActivityInfo object. Use icon on ActivityInfo to populate your cell.
I haven't tried that recipe, but it should get you closer.
TLDR:
I'm setting myListView.setVisibility(View.GONE);, but it's not dissappearing until later... do I need to let it know somehow that I've changed it's visibility? Or do I need to also hide it's inner elements or something?
Description of Problem:
I have a normal news app. You see a list of articles for the "main" section, then you can click the options to select a new section.
When the user clicked, the section title changed, but the articles in the list would just sit there with "old" content until the new content is loaded, then it would flash to the new content.
This isn't ideal obviously. I'd like the list to disappear, show a loading animation, then, after the new data is retrieved (either from DB or online, then DB), it shows the new content.
I found this SO question which seemed like what I want, but...
I'm setting GONE immediately upon selection of the menu, then VISIBLE after it import the articles and loads the new ones... but it's not disappearing at all during that. I know the GONE code works, because if I remove my VISIBLE code, the articles never reappear.
Do I need to say "View.GONE", then tell it to update it's visibility or something?
My Code (MainActivity):
public static void sectionSelected()
{
String selectedText = sectionsSpinner.getSelectedItem().toString();
String[] selectedSection = Section.stringToSection(selectedText);
//check if it was already the current section
if(!Section.isEqual(Section.currentSection, selectedText))
{
//hides list of articles
articleEntryListView.setVisibility(View.GONE);
//sets new currentSection
Section.currentSection = selectedSection; // Section.stringToSection(sectionsSpinner.getSelectedItem().toString());
//imports articles (if it's been more than an hour since last import)
articlesDataSource.importArticles(Section.currentSection, true, false);
//loads article from database to the list
loadArticlesIntoList(Section.currentSection);
}
}
public static void loadArticlesIntoList(String[] section)
{
//clears the list
//articleEntryAdapter.clear(); //don't think I need this now that I'm just going to hide it
//articleEntryAdapter.notifyDataSetChanged();
//POPULATES THE LIST OF ARTICLES, THROUGH THE ADAPTER
for(final Article a1 : articlesDataSource.getArticles(section))
{
articleEntryAdapter.add(a1);
}
articleEntryAdapter.notifyDataSetChanged();
//shows list of articles
articleEntryListView.setVisibility(View.VISIBLE);
}
ADDITION: here is my importAricles() code: http://pastebin.com/8j6JZBej
You have to invalidate the view anytime you make a change to its appearance, so make a call to articleEntryListView.invalidate() after setting the visibility.
I am trying to write a method that will toggle a button from being disabled to being enabled and back using a simple if statement.
I would assume that it would be something like
if (buttonDisable.setEnabled(true) == true){
//do stuff
}
But I haven't had much luck finding my answer via google.
Don't test the display of the model, test the model.
if (buttonDisable.getModel().isEnabled()) {
// do stuff
}
That way if you change the model, you avoid a level of dispatch (view --- updates ---> model --- updates ---> view(s))
A better solution is to make your model changes independent of the view. This way you don't get tied into requiring a specific view to be present to make the model change.
ButtonModel toggle = new ButtonModel();
...
JButton button = new JButton(toggle);
...
// this is clear that we are manipulating the model, not the view
// as new views are added / removed, this toggle will continue to work
toggle.setEnabled(!toggle.isEnabled());
Why not just toggle the state in one shot:
buttonDisable.setEnabled(!buttonDisable.isEnabled())