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how to make a view stay on top alwayson all screens

I have got display over other apps permission in android now how can I make a view that always stays on top and responses to clicks or some gestures

I did this by getting the window.decorView.rootView and adding my inflated layout there.
// parent of activity,
val parent = (context as AppCompatActivity).window.decorView.rootView as? ViewGroup
// inflate view,
view = LayoutInflater.from(context).inflate(R.layout.dialog, parent, false)
// add the view to the parent container,
parent?.addView(dialogView, params)
You can add onClick listeners to the inflated view and its children.

App crashes when setting background colour

Every time I run my app it crashes giving me a nullpointerexception, I want to programatically change my background depending on the scenario, here is my code:
Main Activity:
public class Activity extends AppCompatActivity {
ConstraintLayout layout;
String messageSafe = "Item is Safe for Consumption";
String messageUnSafe = "Item is NOT Safe for Consumption";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_information);
layout = new ConstraintLayout(this);
if (matched.length == 0) {
layout.setBackgroundResource(R.drawable.background_safe);
setContentView(layout);
changeColor("#00FF00");
messageView.setText(messageSafe);
}
else{
layout.setBackgroundResource(R.drawable.background_unsafe);
setContentView(layout);
changeColor("#FF0000");
messageView.setText(messageUnSafe);
}
ListView listContains = (ListView) findViewById(R.id.lvItemsFound);
ArrayAdapter<String> contains = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, foundItems);
listContains.setAdapter(contains);
ListView listRestricted = (ListView) findViewById(R.id.lvItemsRestricted);
ArrayAdapter<String> found = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, matched);
listRestricted.setAdapter(found);
}

You are losing reference to your old view because you changed the layout to a new ConstraintLayout object. This means you now don't have your ListView objects and other items in your XML because that View is gone. It's not the ContentView anymore. If you want to work on the existing layout, you need to give the root view an ID.
<constraintlayout android:id="#+id/container" ... />
Then you can reference that ID with findViewById(R.id.container) and use the object you get from it to change your background like you are doing.
Try this:
1. Give your root view an ID
2. Set a ConstraintLayout object with ConstraintLayout layout = findViewById(R.id.container) (Note: You can call it anything, not just container, I am just going off my example from above, since I gave it the ID 'container')
3. call setBackgroundResource() like you are doing.
4. No need to call setContentView() again, this was set in the beginning, and you do not want to reset it to a new view you just constructed like you were initially doing.
5. You shouldn't crash when trying to call setAdapter() to your ListView now because you don't have a reference to an object that isn't in your content view.
layout = (ConstraintLayout)findViewById(R.id.container);
if (matched.length == 0) {
layout.setBackgroundResource(R.drawable.background_safe);
changeColor("#00FF00"); //assuming this is some local function?
messageView.setText(messageSafe);
}
else{
layout.setBackgroundResource(R.drawable.background_unsafe);
changeColor("#FF0000");
messageView.setText(messageUnSafe);
}

You are trying to set the background by replacing the view of your activity (this is what setContentView() does). This causes a null pointer exception later because the old layout (defined in the XML) has been replaced, so your list view no longer exists.
Instead, you should get a reference to the existing root view (the ConstraintLayout, although if you're just setting background you can just reference it as a View, no need to be so specific), and set the background on it, like so:
findViewById(R.id.container).setBackgroundResource(R.drawable.unsafe);
You'll also need to give the containing layout an id in the existing layout XML:
<android.support.constraint.ConstraintLayout
android:id="#+id/container"
... etc.

How to find the class of a checkbox that was clicked

I have a 'ChecklistItem' class that has the following properties:
private CheckBox checkBox;
private ImageButton noteButton;
private TextView vitalField;
I have an onClick Listener for my checkbox. Now the problem is, when I click on that checkbox and the OnClick() method gets called, how can I figure out what ChecklistItem that checkbox is a part of?
Whenever I click on a checkbox, I want to add the ChecklistItem that the checkbox is a part of to an array, but the OnClick() only knows about the checkbox that called it.
How can I get around this?

Ok so this answer is according to the "long discussion" we had
let's assume you want to make a - re usable - view of your list and you wrote a separate xml layout file called list_item as the following:
<CheckBox
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/checkbox"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/text_view"/>
so now let's assume you are in the activity or fragment or wherever you want to host your view , NOW I have to point out this is just an example , usually a list view is what you would need in this case but again I have very little details about your app so I'm going to keep it simple
Assuming you have a vertical linear layout and you want to add these "rows" to it, each row represents one of your custom view
LinearLayout layout = findViewById(R.id.layout);
LayoutInflater inflater = LayoutInflater.from(this); // This inflater is responsible of creating instances of your view
View myView = inflater.inflate(R.layout.list_item, layout, false); // This view objects is the view you made in your xml file
CheckBox checkBox = (CheckBox) myView.findViewById(R.id.checkbox);
TextView textView = (TextView) myView.findViewById(R.id.text_view);
checkBox.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
//if checkbox is checked enable textview for example
// here you have a reference to all the views you just created
// Weather you want to save them in a class together that's up to you and your app's logic
}
});
layout.addView((myView));
if the list is might exceed the screen height you may want to wrap your linear layout in a scroll view.
BTW: ListView is just a neat way to do this automatically by defining how you want each row to appear, and of course it manages your views for you and recycle them when they get of screen, but I just wanted to point out the concept.
Hope this helps you

android: creat layout dynamically and setContentView it dynamically

Suppose there is an Activity called "m1" and there are two layouts called "m2" and "m3" both have few buttons is dynamically how i can setContentView dynamically whay

You have a method to set view to the setContentView
So you can pass the root parent view to this method to achieve your requirement.

You can pass layout Resource ID or View in setContentView(); method.
try this..
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
LayoutInflater mInflater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
if(viewlayout1){
view = mInflater.inflate(R.layout.layout1,null);
}else{
view = mInflater.inflate(R.layout.layout2,null);
}
setContentView(view);
/*******************/
}

The view hierarchy can have only one root. What setContentView() essentially does is that it sets the root view.
In your case,
Method 1
You'll have to either make one of the layouts as the root and add the other as a child. And call setContentView(root).
Or
Method 2
Create a dummy container layout. Set that as root.
And add both your layouts as children to that container layout.

The specified child already has a parent. You must call removeView() on the child's parent first (Android)

I have to switch between two layouts frequently. The error is happening in the layout posted below.
When my layout is called the first time, there doesn't occur any error and everything's fine. When I then call a different layout (a blank one) and afterwards call my layout a second time, it throws the following error:
> FATAL EXCEPTION: main
> java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.
My layout-code looks like this:
tv = new TextView(getApplicationContext()); // are initialized somewhere else
et = new EditText(getApplicationContext()); // in the code
private void ConsoleWindow(){
runOnUiThread(new Runnable(){
#Override
public void run(){
// MY LAYOUT:
setContentView(R.layout.activity_console);
// LINEAR LAYOUT
LinearLayout layout=new LinearLayout(getApplicationContext());
layout.setOrientation(LinearLayout.VERTICAL);
setContentView(layout);
// TEXTVIEW
layout.addView(tv); // <========== ERROR IN THIS LINE DURING 2ND RUN
// EDITTEXT
et.setHint("Enter Command");
layout.addView(et);
}
}
}
I know this question has been asked before, but it didn't help in my case.

The error message says what You should do.
// TEXTVIEW
if(tv.getParent() != null) {
((ViewGroup)tv.getParent()).removeView(tv); // <- fix
}
layout.addView(tv); // <========== ERROR IN THIS LINE DURING 2ND RUN
// EDITTEXT

simply pass the argument
attachtoroot = false
View view = inflater.inflate(R.layout.child_layout_to_merge, parent_layout, false);

I came here on searching the error with my recyclerview but the solution didn't work (obviously). I have written the cause and the solution for it in case of recyclerview. Hope it helps someone.
The error is caused if in the onCreateViewHolder() the following method is followed:
layoutInflater = LayoutInflater.from(context);
return new VH(layoutInflater.inflate(R.layout.single_row, parent));
Instead it should be
return new VH(layoutInflater.inflate(R.layout.single_row, null));

I got this message while trying to commit a fragment using attach to root to true instead of false, like so:
return inflater.inflate(R.layout.fragment_profile, container, true)
After doing:
return inflater.inflate(R.layout.fragment_profile, container, false)
It worked.

You must first remove the child view from its parent.
If your project is in Kotlin, your solution will look slightly different than Java. Kotlin simplifies casting with as?, returning null if left side is null or cast fails.
(childView.parent as? ViewGroup)?.removeView(childView)
newParent.addView(childView)
Kotlin Extension Solution
If you need to do this more than once, add this extension to make your code more readable.
childView.removeSelf()
fun View?.removeSelf() {
this ?: return
val parentView = parent as? ViewGroup ?: return
parentView.removeView(this)
}
It will safely do nothing if this View is null, parent view is null, or parent view is not a ViewGroup

frameLayout.addView(bannerAdView); <----- if you get error on this line the do like below..
if (bannerAdView.getParent() != null)
((ViewGroup) bannerAdView.getParent()).removeView(bannerAdView);
frameLayout.addView(bannerAdView); <------ now added view

If other solution is not working like:
View view = inflater.inflate(R.layout.child_layout_to_merge, parent_layout, false);
check for what are you returning from onCreateView of fragment is it single view or viewgroup? in my case I had viewpager on root of xml of fragment and I was returning viewpager, when i added viewgroup in layout i didnt updated that i have to return viewgroup now, not viewpager(view).

My error was define the view like this:
view = inflater.inflate(R.layout.qr_fragment, container);
It was missing:
view = inflater.inflate(R.layout.qr_fragment, container, false);

In my case it happens when i want add view by parent to other view
View root = inflater.inflate(R.layout.single, null);
LinearLayout lyt = root.findViewById(R.id.lytRoot);
lytAll.addView(lyt); // -> crash
you must add parent view like this
View root = inflater.inflate(R.layout.single, null);
LinearLayout lyt = root.findViewById(R.id.lytRoot);
lytAll.addView(root);

Simplified in KOTLIN
viewToRemove?.apply {
if (parent != null) {
(parent as ViewGroup).removeView(this)
}
}

In my case, I had id named as "root" for constraint layout, which was conflicting the existing parent root id.
Try to change the id.
<androidx.constraintlayout.widget.ConstraintLayout
android:id="#+id/root" //<--It should not named as root.
android:layout_width="match_parent"
android:layout_height="match_parent"
</androidx.constraintlayout.widget.ConstraintLayout>

In my case the problem was caused by the fact that I was inflating parent View with <merge> layout. In this case, addView() caused the crash.
View to_add = inflater.inflate(R.layout.child_layout_to_merge, parent_layout, true);
// parent_layout.addView(to_add); // THIS CAUSED THE CRASH
Removing addView() helped to solve the problem.

The code below solved it for me:
#Override
public void onDestroyView() {
if (getView() != null) {
ViewGroup parent = (ViewGroup) getView().getParent();
parent.removeAllViews();
}
super.onDestroyView();
}
Note: The error was from my fragment class and by overriding the onDestroy method like this, I could solve it.

My problem is related to many of the other answers, but a little bit different reason for needing to make the change... I was trying to convert an Activity to a Fragment. So I moved the inflate code from onCreate to onCreateView, but I forgot to convert from setContentView to the inflate method, and the same IllegalStateException brought me to this page.
I changed this:
binding = DataBindingUtil.setContentView(requireActivity(), R.layout.my_fragment)
to this:
binding = DataBindingUtil.inflate(inflater, R.layout.my_fragment, container, false)
That solved the problem.

You just need to pass attachToRoot parameter false.
mBinding = FragmentCategoryBinding.inflate(inflater, container, false)

If you're using ViewBinding, make sure you're referring to the right binding!
I had this issue when I was trying to inflate a custom dialog from within an activity:
AlertDialog.Builder builder = new AlertDialog.Builder(this);
final AlertBinding alertBinding = AlertBinding.inflate(LayoutInflater.from(this), null, false);
builder.setView(binding.getRoot()); // <--- I was using binding (which is my Activity's binding), instead of alertBinding.

This is how I do my custom dialog
AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
android.view.View views = getLayoutInflater().inflate(layout_file, null, false);
builder.setView(views);
dialog = builder.create();
dialog.show();
I changed it into this and its works for me, I hope this helps
Dialog dialog = new Dialog(MainActivity.this);
dialog.setContentView(layout_file);
dialog.show();

check if you already added the view
if (textView.getParent() == null)
layout.addView(textView);

if(tv!= null){
((ViewGroup)tv.getParent()).removeView(tv); // <- fix
}

I was facing the same error, and look what I was doing. My bad, I was trying to add the same view NativeAdView to the multiple FrameLayouts, resolved by creating a separate view NativeAdView for each FrameLayout, Thanks

In my case I was accidentally returning a child view from within Layout.onCreateView() as shown below:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v= inflater.inflate(R.layout.activity_deliveries, container, false);
RecyclerView rv = (RecyclerView) v.findViewById(R.id.deliver_list);
return rv; // <- here's the issue
}
The solution was to return the parent view (v) instead of the child view (rv).

I found another fix:
if (mView.getParent() == null) {
myDialog = new Dialog(MainActivity.this);
myDialog.setContentView(mView);
createAlgorithmDialog();
} else {
createAlgorithmDialog();
}
Here i just have an if statement check if the view had a parent and if it didn't Create the new dialog, set the contentView and show the dialog in my "createAlgorithmDialog()" method.
This also sets the positive and negative buttons (ok and cancel buttons) up with onClickListeners.

In my case, I had an adapter which worked with a recyclerView, the items that were being passed to the adapter were items with their own views.
What was required was just a LinearLayout to act as a container for every item passed, so what I was doing was to grab the item in the specified position inside onBindViewHolder then add it to the LinearLayout, which was then displayed.
Checking the basics in docs,
When an item scrolls off the screen, RecyclerView doesn't destroy its
view
Therefore, with my items, when I scroll towards a direction, then change towards the opposite direction - fast, the racently displayed items have not been destroyed, meaning, the items are still associated with the LinearLayout container, then on my end, I'm trying to attach to another container, which ends up with a child having a parent already.
My solution was to check if the specified item has a parent, if it has, I assign it to a variable, then call parentVar.removeView(item), then assign the new parent.
Here's the sample code(Problematic Adapter):
override fun onBindViewHolder(holder: QuestionWidgetViewHolder, position: Int) {
holder.linearLayoutContainer.removeAllViewsInLayout()
val questionWidget: QuestionWidget =
dataSource[position]
questionWidget.setValueChangedListener(this)
holder.linearLayoutContainer.addView(questionWidget)/*addView throws error once in a while*/
}
inner class QuestionWidgetViewHolder(mView: View) :
RecyclerView.ViewHolder(mView) {
val linearLayoutContainer: LinearLayout =
mView.findViewById(R.id.custom_question_widget_container)
}
Content of the R.id.custom_question_widget_container:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/custom_question_widget_container"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="10dp"
android:orientation="vertical"
android:padding="10dp" />
So, the questionWidget seems to have been retaining the parent for almost 4 steps outside visibility, and when I scroll to the opposite direction fast, I would encounter it still with its parent, then I'm attempting to add it to another container.
Here's the fix - option 1:
override fun onBindViewHolder(holder: QuestionWidgetViewHolder, position: Int) {
holder.linearLayoutContainer.removeAllViewsInLayout()
val questionWidget: QuestionWidget =
dataSource[position]
questionWidget.setValueChangedListener(this)
val initialWidgetParent : ViewParent? = questionWidget.parent
//attempt to detach from previous parent if it actually has one
(initialWidgetParent as? ViewGroup)?.removeView(questionWidget)
holder.linearLayoutContainer.addView(questionWidget)
}
Another better solution - option 2:
override fun onBindViewHolder(holder: QuestionWidgetViewHolder, position: Int) {
holder.linearLayoutContainer.removeAllViewsInLayout()
val questionWidget: QuestionWidget =
dataSource[position]
questionWidget.setValueChangedListener(this)
val initialWidgetParent : ViewParent? = questionWidget.parent
//if it's in a parent container already, just ignore adding it to a view, it's already visible
if(initialWidgetParent == null) {
holder.linearLayoutContainer.addView(questionWidget)
}
}
Actually, it's much of asking the child if it has a parent before adding it to a parent.

I tried all the things that you guys suggested, with no luck.
But, I managed to fix it by moving all my binding initializations from onCreate to onCreateView.
onCreate(){
binding = ScreenTicketsBinding.inflate(layoutInflater)
}
MOVE TO
onCreateView(...){
binding = ScreenTicketsBinding.inflate(layoutInflater)
}

You can use this methode to check if a view has children or not .
public static boolean hasChildren(ViewGroup viewGroup) {
return viewGroup.getChildCount() > 0;
}

My case was different the child view already had a parent view i am adding the child view inside parent view to different parent. example code below
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="#dimen/lineGap"
>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#color/black1"
android:layout_gravity="center"
android:gravity="center"
/>
</LinearLayout>
And i was inflating this view and adding to another LinearLayout, then i removed the LinaarLayout from the above layout and its started working
below code fixed the issue:
<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="center"
android:textColor="#color/black1" />

It happened with me when I was using Databinding for Activity and Fragments.
For fragment - in onCreateView we can inflate the layout in traditional way using inflater.
and in onViewCreated method, binding object can be updated as
binding = DataBindingUtil.getBinding<FragmentReceiverBinding>(view) as FragmentReceiverBinding
It solved my issue

In my case, I was doing this (wrong):
...
TextView content = new TextView(context);
for (Quote quote : favQuotes) {
content.setText(quote.content);
...
instead of (good):
...
for (Quote quote : favQuotes) {
TextView content = new TextView(context);
content.setText(quote.content);
...

If you are working with MaterialAlertDialog, this worked for me:
(yourChildView.parent as? ViewGroup)?.removeView(yourChildView)

If in your XML you have layout with id "root" It`s problem, just change id name