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Save ui elements in activity state

I am totaly new to java and android. I have the following UI setup:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<EditText
android:id="#+id/textView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
...
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent" />
<ScrollView
android:id="#+id/scrollView"
android:layout_width="match_parent"
android:layout_height="0dp"
...>
<LinearLayout
android:id="#+id/linLay"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical" />
</ScrollView>
</androidx.constraintlayout.widget.ConstraintLayout>
During runtime, some TextViews will be added to the LinearLayout. I have following problem. The phone filps, the dynamicaly added TextViews disapeare. The reason ist that the onCreate(Bundle savedInstanceState) method of the activity is called, if you flip your phone.
I setup the following method, to save the instance state (textViews is a member of the Activity class (Vector)):
protected void onSaveInstanceState(Bundle state) {
super.onSaveInstanceState(state);
//Save the TextViews
textViews.removeAllElements();
LinearLayout layout = getLinearLayout();
while (layout.getChildCount() > 0)
{
View view = layout.getChildAt(0);
if (view instanceof TextView)
{
layout.removeView(view);
textViews.add((TextView) view);
}
}
state.putSerializable("textViews", textViews);
}
I implemented this cod in the onCreate(Bundle savedInstanceState) method to restore the TextViews:
LinearLayout linLay = getLinearLayout();
//Load TextViews
if ((savedInstanceState != null) && (savedInstanceState.getSerializable("textViews") != null))
{
Serializable serializable = savedInstanceState.getSerializable("textViews");
if (serializable instanceof Vector)
{
textViews= (Vector<TextView>) serializable;
}
}
if (textViews!= null) {
for (TextView textView : textViews) {
linLay.addView(textView);
}
}
This code works for the fliping issue, but it creates a new issue. If I press the home button, I get the following error:
Parcel: unable to marshal value
I read that the problem is that Vector<TextView> is not serializable. But why does fliping the phone does not effect this error? I debugt the app and I am sure, the state.putSerializable(...) method is called, if the phone is fliped.
How would you store a TextView instead? It is not possible to save a String instead of the TextView, because the backgroundResource of the TextViews differ.

I know that this int solution, but hear me out. TextViews are bunch of text on the screen right? my advice would be when activity recreation will happen dont save TextViews as themselves save text thats in the TextView. and after that use them to draw new ones. this is more logical, more optimized and by using ViewModel it can become more elegant by storing that texts in LiveData of List and observing and reacting in activity. here is documentation for it: LiveData and ViewModel

MapView in lite mode causes RecyclerView to not scroll correctly

I'm building a chat app in Android Studio with the abitily to send routes on a map. I've implemented this by using a RecyclerView and ViewHolders, which hold the necessary UI with MapViews in lite mode (map:liteMode="true"). Thing is, when I add a map UI element to the recyclerView and scroll to the end by using scrollToPosition(adapter.getItemCount() - 1), the scrolling has trouble following the views and is always slightly off, as seen on the screenshot
(https://i.postimg.cc/BvMzrHJL/Screenshot-20190526-005535.png).
Moreover, the keyboard gets confused about the height of the views as well when clicked (https://i.postimg.cc/Hs6BsHfR/Screenshot-20190526-011647.png).
I have tried switching lite mode off, but it makes the scrolling laggy and handling lifecycle events becomes an issue since my MapViews are in ViewHolders, not in Activities or Fragments, see official documentation:
Users of this class [MapView] must forward all the life cycle methods from the
Activity or Fragment containing this view to the corresponding ones in
this class.
I have also tried changing the height of the layout from android:layout_height="wrap_content" to android:layout_height="250dp", but that also didn't work at all.
Also, scrolling works just fine with Views containing only text or an empty RelativeLayout istead of MapView.
I used this sample from Google's developer documentation https://github.com/googlemaps/android-samples/blob/master/ApiDemos/java/app/src/main/java/com/example/mapdemo/LiteListDemoActivity.java
So here is my ViewHolder (one of two):
private class SentRouteViewHolder extends RecyclerView.ViewHolder implements OnMapReadyCallback
{
MapView sentMap;
TextView routeSentTime;
GoogleMap map;
public SentRouteViewHolder(#NonNull View itemView) {
super(itemView);
sentMap = itemView.findViewById(R.id.sent_map);
routeSentTime = itemView.findViewById(R.id.route_sent_time);
sentMap.onCreate(null);
sentMap.onResume();
sentMap.getMapAsync(this);
}
#Override
public void onMapReady(GoogleMap googleMap) {
MapsInitializer.initialize(getApplicationContext());
map = googleMap;
setMapRoute();
}
void bind(Message message)
{
sentMap.setTag(message);
setMapRoute();
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("HH:mm");
routeSentTime.setText(simpleDateFormat.format(message.getTime()));
}
void setMapRoute()
{
if(map == null) return;
Message message = (Message) sentMap.getTag();
if(message==null) return;
map.setMapType(GoogleMap.MAP_TYPE_NORMAL);
}
}
And adding the item to the RecyclerView:
activeCollection.add(newMessage).addOnSuccessListener(documentReference -> {
documentReference.get().addOnSuccessListener(documentSnapshot -> {
adapter.addMessage(documentSnapshot);
adapter.notifyItemInserted(adapter.getItemCount());
chatReycler.scrollToPosition(adapter.getItemCount()-1);
});
});
The onBindViewHolder:
SentRouteViewHolder routeViewHolder = (SentRouteViewHolder) viewHolder;
routeViewHolder.bind(message);
The onCreateViewHolder:
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.route_sent,parent,false);
Log.v("measure",String.valueOf(v.getMeasuredHeight()));
return new SentRouteViewHolder(v);
RecyclerView configuration:
manager.setStackFromEnd(true);
chatReycler.setLayoutManager(manager);
chatReycler.setAdapter(adapter);
chatReycler.setHasFixedSize(false);
chatReycler.setRecyclerListener(viewHolder -> {
if(viewHolder.getItemViewType()==ChatRecyclerViewAdapter.VIEW_TYPE_ROUTE_RECEIVED)
{
ChatRecyclerViewAdapter.ReceivedRouteViewHolder holder = (ChatRecyclerViewAdapter.ReceivedRouteViewHolder) viewHolder;
if(holder.map!=null)
{
holder.map.clear();
holder.map.setMapType(GoogleMap.MAP_TYPE_NONE);
}
}
else if (viewHolder.getItemViewType()==ChatRecyclerViewAdapter.VIEW_TYPE_ROUTE_SENT)
{
ChatRecyclerViewAdapter.SentRouteViewHolder holder = (ChatRecyclerViewAdapter.SentRouteViewHolder) viewHolder;
if(holder.map!=null)
{
holder.map.clear();
holder.map.setMapType(GoogleMap.MAP_TYPE_NONE);
}
}
});
The ViewHolder XML file
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
xmlns:tools="http://schemas.android.com/tools"
android:paddingBottom="3dp"
android:layout_marginBottom="13dp">
<ImageView
android:id="#+id/route_received_background"
android:layout_width="250dp"
android:layout_height="250dp"
android:layout_marginStart="15dp"
android:src="#drawable/message_received_background"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<com.google.android.gms.maps.MapView
xmlns:map="http://schemas.android.com/apk/res-auto"
android:id="#+id/received_map"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_margin="9dp"
app:layout_constraintBottom_toBottomOf="#+id/route_received_background"
app:layout_constraintEnd_toEndOf="#+id/route_received_background"
app:layout_constraintStart_toStartOf="#+id/route_received_background"
app:layout_constraintTop_toTopOf="#+id/route_received_background"
map:mapType="normal"
map:liteMode="true"
/>
<TextView
android:id="#+id/route_received_time"
style="#style/TextAppearance.MaterialComponents.Caption"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="6dp"
android:textSize="13sp"
app:layout_constraintBottom_toBottomOf="#+id/route_received_background"
app:layout_constraintStart_toEndOf="#+id/route_received_background"
tools:text="11:50" />
</android.support.constraint.ConstraintLayout>
I want the RecyclerView to scroll to the bottom of the sent map, and not to the middle of it. How can I make that happen?

I had a similar problem with scrolling and checked that the parent layout was 0dp high. I changed it to match_parent and it worked.
android:id="#+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent"

Inflated xml Layout with a TextView has an onClick attribute, but it does not get called.

I have an XML layout file that has a TextView within a CoordinatorLayout.
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:tools="http://schemas.android.com/tools"
tools:context=".SpecificProgramSelectionActivity">
<TextView
android:layout_width="match_parent"
android:layout_height="75dp"
android:id="#+id/saved_program"
android:text="Empty"
android:textAlignment="center"
android:gravity="fill"
android:textSize="20dp"
android:background="#drawable/program_selection_border"
android:textColor="#color/black"
android:clickable="true"
android:focusable="true"
android:onClick="addToSavedPrograms"
android:paddingTop="5dp"
android:paddingBottom="5dp"/>
And this code that inflates the layout and adds it into a Linear Layout in the activity's view.
for (PlayerWithObjectives player : players){
name = player.getName();
for (String objective : player.getObjectives()){
objectives.add(objective);
}
nameView = inflater.inflate(R.layout.inflatable_player_name_view, null);
((TextView)nameView.findViewById(R.id.saved_program)).setText(name);
((TextView)nameView.findViewById(R.id.saved_program)).setTextAlignment(View.TEXT_ALIGNMENT_CENTER);
((TextView)nameView.findViewById(R.id.saved_program)).setTextSize(20);
linearLayout.addView(nameView);
}
(This is the activity's layout XML)
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".SpecificProgramSelectionActivity"
android:orientation="vertical">
<ScrollView
android:layout_width="match_parent"
android:layout_height="wrap_content">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:id="#+id/specific_program_selection_linear_layout">
</LinearLayout>
</ScrollView>
Everything looks fine in the app when I run it. Every inflated view shows up, the only issue is that the method that I specified in the onClick attribute for the inflated TextView does not get called. Why is that? Here is the method that is supposed to be called
public void addToSavedPrograms(View view){
String name = (String) (((TextView)view.findViewById(R.id.saved_program)).getText());
namesToSend.add(name);
editor.putStringSet("Tracked Players", namesToSend);
editor.commit();
Toast.makeText(getApplicationContext(),name + " was saved to preferences.", Toast.LENGTH_SHORT);
}
Why doesn't the method get called? I already saw all the other threads about using setContent() and stuff but that didn't work and it was not explained that great in the answer. Any help would be greatly appreciated.

public class YourActivity extends AppCompatActivity implements OnClickListener{
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TextView textview=(TextView)findViewById(R.id.saved_program);
textview.setOnClickListener(this);
}
#Override
public void onClick(View view) {
switch(view.getId()){
case R.id.saved_program:
//call your function here
default:
break;
}
}
you can do it like this.

Update:
First off, thank you to everybody that commented, your help was greatly appreciated. Your no judgment assistance is an awesome and welcome change from a lot of what I have experienced and seen on in this community.
Secondly, I figured out my issue. Or got my code to work at least. Once I got a better understanding of inflating layouts I changed this line of code
nameView = inflater.inflate(R.layout.inflatable_player_name_view, null);
To
nameView = (TextView) inflater.inflate(R.layout.inflatable_add_player_name_view, linearLayout, false);
The difference is that When you inflate, it returns an object that is the same type as the top parent in the specified layout file (Which in this case is "R.layout.inflatable_player_name_view"). So I changed nameView to a TextView object and cast the returned object as a TextView. Then I specified the wanted parent layout (To get the right layoutParams) and put false so that it does not attach it automatically to that parent layout. After that I simply made the alterations to the textView that I wanted, like setting the text values and whatnot, and then manually added it to the parent linearlayout that I wanted. After doing this there was not even a need to set an onClickListener programmatically because the android:onClick method worked just fine.

Textview.setText throwing nullpointer despite the view being in the correct contentView

Before any of you tell me that this has been answered many times before, let me clarify most of those who've asked this question either gave the wrong view id or set a different ContentView than where the TextView was located. I have already used this function in a different where it worked fine. I've tried using a string literal in the TextView.setText(), but it was futile.
contactstory.xml file
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="#+id/textyman"
android:layout_width="match_parent"
android:layout_height="300dp"
android:layout_marginTop="100dp"
android:text="TextView" />
<Button
android:id="#+id/close"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Close" />
</LinearLayout>
Function in java file
public void ShowStory(int pos)
{
final Dialog dialog = new Dialog(this);
dialog.setTitle(srcnames[pos]);
dialog.setContentView(R.layout.contactstory);
String username=getIntent().getStringExtra("username");
LoginDataBaseAdapter loginDataBaseAdapter=new
LoginDataBaseAdapter(this);
loginDataBaseAdapter.open();
String story=loginDataBaseAdapter.GetStory(pos,username);
TextView t1=(TextView)findViewById(R.id.textyman);
Button btnend=(Button)findViewById(R.id.close);
if(TextUtils.isEmpty(story)){
t1.setText(username+" hasn't added any story for this song");
}
else {
t1.setText(story); //Exception is thrown here
}
btnend.setOnClickListener(new View.OnClickListener(){
public void onClick(View v) {
dialog.dismiss();
}
});
dialog.show();
}
Logcat
FATAL EXCEPTION: main
java.lang.NullPointerException
at com.example.sherry.escuchame.ContactInfo.ShowStory(ContactInfo.java:157)
at
com.example.sherry.escuchame.ContactInfo.onContextItemSelected
(ContactInfo.java:140)
at android.app.Activity.onMenuItemSelected(Activity.java:2660)
at android.support.v4.app.FragmentActivity.onMenuItemSelected
(FragmentActivity.java:408)
at
android.support.v7.app.AppCompatActivity.onMenuItemSelected
(AppCompatActivity.java:195)
at android.support.v7.view.WindowCallbackWrapper.onMenuItemSelected
(WindowCallbackWrapper.java:113)

Don't set pass layout id directly like R.layout.contactstory instead use layout inflater to inflate layout like below code
View view = LayoutInflater.from(context).inflate(R.layout.contactstory,null);
dialog.setContentView(view);
TextView t1=(TextView)view.findViewById(R.id.textyman);

android - global layout refresh function

EDIT 2:
In my MainActivity I have a function (displayData) that displays the substitutions for my school.
public void displayData(List<Schoolday> results) {
TabLayout mainTabLayout = (TabLayout) findViewById(R.id.mainTabLayout);
ViewPager mainViewPager = (ViewPager) findViewById(R.id.mainViewPager);
// draw the tabs depending on the days from the file
mainTabLayout.removeAllTabs();
for (int n = 0; n < results.size(); n++) {
List<Subject> subjectsToDisplay = new ArrayList<>();
if (myPreferences.getBoolean(SHOW_WHOLE_PLAN, true)) {
subjectsToDisplay = results.get(n).getSubjects();
} else {
List<Subject> tempSubjectsToDisplay;
tempSubjectsToDisplay = results.get(n).getSubjects();
for (int i = 0; i < tempSubjectsToDisplay.size(); i++) {
if (tempSubjectsToDisplay.get(i).getCourse().contains(myPreferences.getString(CLASS_TO_SHOW, "None"))) {
subjectsToDisplay.add(tempSubjectsToDisplay.get(i));
}
}
}
results.get(n).setSubjects(subjectsToDisplay);
// only create a tab if there's any information to show within that tab
if (results.get(n).getSubjects().size() > 0) {
mainTabLayout.addTab(mainTabLayout.newTab().setText(results.get(n).getDate().substring(0, 6)));
}
}
PagerAdapter pagerAdapter = new PagerAdapter(getSupportFragmentManager(), mainTabLayout.getTabCount(), results);
mainViewPager.setAdapter(pagerAdapter);
mainViewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(mainTabLayout));
mainTabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
#Override
public void onTabSelected(TabLayout.Tab tab) {
mainViewPager.setCurrentItem(tab.getPosition());
}
#Override
public void onTabUnselected(TabLayout.Tab tab) {
}
#Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
}
This is my main layout:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/main_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<android.support.design.widget.TabLayout
android:id="#+id/mainTabLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="?attr/colorPrimary"
android:elevation="6dp"
android:minHeight="?attr/actionBarSize"
android:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar"
app:tabGravity="fill" />
<android.support.v4.view.ViewPager
android:id="#+id/mainViewPager"
android:layout_width="match_parent"
android:layout_height="fill_parent"
android:layout_below="#id/mainTabLayout" />
</RelativeLayout>
And this is the layout of the fragment that represents a page in the ViewPager:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v4.widget.SwipeRefreshLayout
android:id="#+id/mainSwipeContainer"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v7.widget.RecyclerView
android:id="#+id/mainRecyclerView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true" />
</android.support.v4.widget.SwipeRefreshLayout>
</RelativeLayout>
Whenever a refresh is triggered by the SwipeRefreshLayout I need the function displayData to be called.
How can I call this function since the call comes from within a fragment/page from the ViewPager and displayData is not static?
Old question:
I've been searching around quite a while but couldn't find an answer. Maybe I've searched for the wrong thing - just pointing me to that would already help.
My project (Vertretungsplan on github) displays the substitution plan for my school which is available to view/download as an xml file (xml file from school website). I then display the data in my app.
I have a TabLayout (different tabs represent different days) and a connected ViewPager. Each page is using a fragment. Each fragment includes a RecyclerView (to display the results) which is wrapped in a SwipeRefreshLayout.
When I want to refresh the data with the SwipeRefreshLayout I need to download all the data again and then update all the pages as well as the TabLayout(a new day might have a been added so a new tab will be needed). Since my refresh happens inside a fragment but I'm referencing the TabLayout as well as the ViewPager from my MainActivity I have no clue how to properly access all the elements in order to update the content.
My idea was to set up a Broadcast to let my MainActivity know that it needs to refresh the page since it originally set up the whole layout but maybe there is a better solution for that?
I'm kinda new to stackoverflow so feel free to correct me in the way of asking things here! If there's anything other information you need just ask me!
I appreciate your help!!

There are a couple ways to implement what you are asking. The most direct way is to create an interface for the Activity that the Fragment uses. See the docs here:
http://developer.android.com/training/basics/fragments/communicating.html
The other option, which decouples the Fragment from the Activity (which some may see as an advantage) is to use an Intent. With that approach, you need to look into the onNewIntent method, as it is not obvious exactly how it works.
Either one should be fine, especially since you are exploring ideas at this point.