findViewByID returns null

Question

First of all: yes, I read all the other threads on this topic. And not only those from this site... (you see, I'm a little frustrated)

Most of them come with the advice to use android:id instead of just id in the XML file. I did.

From others, I learned, that View.findViewById works different than Activity.findViewById. I handled that, too.

In my location_layout.xml, I use:

<FrameLayout .... >
    <some.package.MyCustomView ... />

    <LinearLayout ... >
        <TextView ...
            android:id="@+id/txtLat" />
        ...
    </LinearLayout>
</FrameLayout>

In my Activity I do:

...
setContentView( R.layout.location_layout );

and in my custom view class:

... 
TextView tv = (TextView) findViewById( R.id.txtLat );

which returns null. Doing this, my Activity works fine. So maybe it's because of the Activity.findViewById and View.findViewById differences. So I stored the context passed to the customs view constructor locally and tried:

...
TextView tv = (TextView) ((Activity) context).findViewById( R.id.txtLat );

which also returned null.

Then, I changed my custom view to extend ViewGroup instead View and changed the location_layout.xml to let the TextView be a direct child of my custom view, so that the View.findViewById should work as supposed. Suprise: it didn't solve anything.

So what the heck am I doing wrong?

I'll appreciate any comments.

This may occur if the project is corrupted too. I fixed it by cleaning the project — Pacerier, Feb 14 '12 at 10:07
@Pacerier "Clean project" solved my problem too. It seems Dropbox corrupted the project. — Kohki Mametani, Jan 02 '20 at 23:14

CommonsWare · Accepted Answer · 2015-10-12T16:58:32.023

304

which returns null

Possibly because you are calling it too early. Wait until onFinishInflate(). Here is a sample project demonstrating a custom View accessing its contents.

edited Oct 12 '15 at 16:58

answered Jul 16 '10 at 12:07

CommonsWare

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77

OMG! Cant believe I spend days on something so trivial. I moved setContentView() above the findViewById() call and that did t he trick. thanks! – agentcurry Jan 26 '12 at 20:35
2

@CommonsWare it that the correct project? I do not see onFinishInflate anywhere in https://github.com/commonsguy/cw-advandroid/tree/master/Animation/SlidingPanel/ – likejudo Oct 12 '15 at 16:43
1

@likejiujitsu: It might have had that back in 2010. I have updated the link to a newer project that has `onFinishInflate()`. – CommonsWare Oct 12 '15 at 16:58
6

I have my setContentView called before findViewById and it is still null. I am referencing an EditText – Neon Warge Feb 13 '16 at 09:58
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Always link to fixed GitHub commits (e.g. https://github.com/commonsguy/cw-omnibus/tree/bbf4a50e02cdf3b45cfb2bb74a6c75a7931224e9/Jank/ThreePaneBC ) and never delete repos or rebase ;-) – Ciro Santilli OurBigBook.com Feb 14 '16 at 16:22
If you're in a Fragment, call getView() for the top-level View: http://stackoverflow.com/questions/6495898/findviewbyid-in-fragment – technocrat Oct 27 '16 at 02:27
1

`public void onActivityCreated(Bundle savedInstanceState)` I just call it inside here if I need to call it when the activity is created if using inside of a fragment class – Justin Mitchell Nov 07 '16 at 00:07

score 168 · Answer 2 · edited Nov 17 '11 at 09:44

168

Possibly, you are calling findViewById before calling setContentView? If that's the case, try calling findViewById AFTER calling setContentView

edited Nov 17 '11 at 09:44

eeerahul

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answered Nov 17 '11 at 09:33

Bayram Boyraz

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1

Such an easy mistake tot make but unfortunately this is what I had done. The debugger is no use since it said the error was at my new intent line not in the actual new activity I was calling. Thanks! – edude05 Apr 13 '12 at 01:23
8

Actually I had this error because I was calling setContentView pointing to the wrong view ... unfortunately the compiler doesn't catch this type of error. – HeatfanJohn Feb 12 '13 at 16:23
Yes, I have deleted setContentView by mistake and didn't understand why my program started to crush. – Ronen Festinger Jul 15 '16 at 18:23

score 106 · Answer 3 · answered Nov 05 '11 at 04:06

106

Make sure you don't have multiple versions of your layout for different screen densities. I ran into this problem once when adding a new id to an existing layout but forgot to update the hdpi version. If you forget to update all versions of the layout file it will work for some screen densities but not others.

answered Nov 05 '11 at 04:06

Joe

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THANKS! That was it. (In my case I have multiple versions for different Android version). I forget about it all the time although I put a gigantic comment on top and bottom of every layout file. I wish the compiler would make an error or big warning if this happens. – tiktak Jan 20 '13 at 12:28
Ding ding ding, thank you so much! Was bending my brain over this lol – Zach Apr 19 '19 at 00:17
I spent 1.5 man days to figure out this. Only your explaination solves my problem (not setContentView / findViewById sequence issue as many Google results told me) Thanks!! – oOEric Sep 25 '20 at 08:09

score 37 · Answer 4 · answered Jun 02 '15 at 17:57

37

FindViewById can be null if you call the wrong super constructor in a custom view. The ID tag is part of attrs, so if you ignore attrs, you delete the ID.

This would be wrong

public CameraSurfaceView(Context context, AttributeSet attrs) {
        super(context);
}

This is correct

public CameraSurfaceView(Context context, AttributeSet attrs) {
        super(context,attrs);
}

answered Jun 02 '15 at 17:57

repkap11

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I made this mistake when I created my custom view. Thank you, repkap11. – Andrew F. Aug 09 '16 at 17:47

Neil Townsend · Answer 5 · 2014-12-23T14:13:18.173

19

Alongside the classic causes, mentioned elsewhere:

Make sure you've called setContentView() before findViewById()
Make sure that the id you want is in the view or layout you've given to setContentView()
Make sure that the id isn't accidentally duplicated in different layouts

There is one I have found for custom views in standard layouts, which goes against the documentation:

In theory you can create a custom view and add it to a layout (see here). However, I have found that in such situations, sometimes the id attribute works for all the views in the layout except the custom ones. The solution I use is:

Replace each custom view with a FrameLayout with the same layout properties as you would like the custom view to have. Give it an appropriate id, say frame_for_custom_view.

In onCreate:

setContentView(R.layout.my_layout);
FrameView fv = findViewById(R.id.frame_for_custom_layout);
MyCustomView cv = new MyCustomView(context);
fv.addView(cv);

which puts the custom view in the frame.

edited Dec 23 '14 at 14:13

answered Dec 20 '14 at 09:06

Neil Townsend

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This helped me: "Make sure that the id you want is in the view or layout you've given to setContentView()". What to do when it's a subview however? Tried getting the parent view then do parentView.findById() but it's still returning null – NaturalBornCamper Dec 23 '17 at 18:26
@naturalborncamper if you post a separate question with example code I’ll have a look at it. – Neil Townsend Dec 24 '17 at 09:18
Thanks Neil, I already posted and someone pointed a better way to do this, although it's not working exactly how it should be so I had to use a different strategy: https://stackoverflow.com/questions/47955376/get-subview-of-loaded-view-group-inside-a-drawer/47955507 – NaturalBornCamper Dec 25 '17 at 20:25

score 16 · Answer 6 · answered Jan 14 '13 at 15:04

In my case, I had 2 activites in my project, main.xml and main2.xml. From the beginning, main2 was a copy of main, and everything worked well, until I added new TextView to main2, so the R.id.textview1 became available for the rest of app. Then I tried to fetch it by standard calling:

TextView tv = (TextView) findViewById( R.id.textview1 );

and it was always null. It turned out, that in onCreate constructor I was instantiating not main2, but the other one. I had:

setContentView(R.layout.main);

instead of

setContentView(R.layout.main2);

I noticed this after I arrived here, on the site.

score 12 · Answer 7 · answered Jun 18 '14 at 00:24

12

    @Override
protected void onStart() {
         // use findViewById() here instead of in onCreate()
    }

answered Jun 18 '14 at 00:24

Jonathan

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score 6 · Answer 8 · answered Jul 09 '16 at 02:19

FWIW, I don't see that anyone solved this in quite the same way as I needed to. No complaints at compile time, but I was getting a null view at runtime, and calling things in the proper order. That is, findViewById() after setContentView(). The problem turned out that my view is defined in content_main.xml, but in my activity_main.xml, I lacked this one statement:

<include layout="@layout/content_main" />

When I added that to activity_main.xml, no more NullPointer.

The problem with copy pasting a Fragment is that you forget to change some things sometimes... being the correct layout to inflate one of them. Thanks! — Pablo Quemé, Jan 05 '18 at 23:31

score 6 · Answer 9 · answered Jan 23 '12 at 22:25

A answer for those using ExpandableListView and run into this question based on it's title.

I had this error attempting to work with TextViews in my child and group views as part of an ExpandableListView implementation.

You can use something like the following in your implementations of the getChildView() and getGroupView() methods.

        if (convertView == null) {
            LayoutInflater inflater =  (LayoutInflater) myContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = inflater.inflate(R.layout.child_layout, null);
        }

I found this here.

score 5 · Answer 10 · answered Apr 21 '14 at 20:03

5

I'm pretty new to Android/Eclipse, by mistake I added the UI stuff to activity_main.xml instead of fragment_main.xml. Took me some hours to figure that out...

answered Apr 21 '14 at 20:03

kungfooman

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score 3 · Answer 11 · answered Jul 16 '14 at 16:09

I had this same problem. I was using a third-party library that allows you to override their adapter for a GridView and to specify your own layout for each GridView cell.

I finally realized what was happening. Eclipse was still using the library's layout xml file for each cell in the GridView, even though it gave no indication of this. In my custom adapter, it indicated that it was using the xml resource from my own project even though at runtime, it wasn't.

So what I did was to make sure my custom xml layouts and ids were different from those still sitting in the library, cleaned the project and then it started reading the correct custom layouts that were in my project.

In short, be careful if you're overriding a third-party library's adapter and specifying your own layout xml for the adapter to use. If your layout inside your project has the same file name as that in the library, you might encounter a really difficult-to-find bug!

score 3 · Answer 12 · answered Mar 29 '15 at 14:41

In my particular case, I was trying to add a footer to a ListView. The following call in onCreate() was returning null.

TextView footerView = (TextView) placesListView.findViewById(R.id.footer);

Changing this to inflate the footer view instead of finding it by ID solved this issue.

View footerView = ((LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE)).inflate(R.layout.footer_view, null, false);

score 3 · Answer 13 · answered Jun 15 '16 at 17:54

Just wanted to throw my specific case in here. Might help someone down the line.

I was using the directive in my Android UI XML like this:

Parent view:

<FrameLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:tag="home_phone"
    android:background="@color/colorPrimary">

    ...

    <include
        layout="@layout/retry_button"
        android:visibility="gone" />

Child view (retry_button):

<com.foo.RetryButton
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/retry"
    android:layout_gravity="center"
    android:orientation="vertical"
    android:layout_width="100dp"
    android:layout_height="140dp">

.findViewById(R.id.retry) would always return null. But, if I moved the ID from the child view into the include tag, it started working.

Fixed parent:

<FrameLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:tag="home_phone"
    android:background="@color/colorPrimary">

    ...

    <include
        layout="@layout/retry_button"
        android:id="@+id/retry"
        android:visibility="gone" />

Fixed child:

<com.foo.RetryButton
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_gravity="center"
    android:orientation="vertical"
    android:layout_width="100dp"
    android:layout_height="140dp">

score 2 · Answer 14 · answered Nov 26 '12 at 10:44

2

In my case, I was using ExpandableListView and I had set android:transcriptMode="normal". This was causing few children in expandable group to disappear and I used to get NULL exception when ever I used scroll the list.

answered Nov 26 '12 at 10:44

Jeevan

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score 2 · Answer 15 · answered Jan 27 '14 at 14:48

For me I had two xml layouts for the same activity - one in portrait mode and one in landscape. Of course I had changed the id of an object in the landscape xml but had forgotten to make the same change in the portrait version. Make sure if you change one you do the same to the other xml or you will not get an error until you run/debug it and it can't find the id you didn't change. Oh dumb mistakes, why must you punish me so?

score 2 · Answer 16 · answered Jun 26 '14 at 09:49

2

Set the activity content from a layout resource. ie.,setContentView(R.layout.basicXml);

answered Jun 26 '14 at 09:49

Ajay Takur

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score 2 · Answer 17 · answered Mar 30 '15 at 08:48

In addition of the above solutions you make sure the
tools:context=".TakeMultipleImages" in the layout is same value in the mainfest.xml file :
android:name=".TakeMultipleImages" for the same activity element. it is occur when use copy and paste to create new activity

score 2 · Answer 18 · answered Aug 31 '15 at 06:46

I have the same problem, but I think its worth sharing with you guys. If you have to findViewById in custom layout, for example:

public class MiniPlayerControllBar extends LinearLayout {
    //code
}

you cannot get the view in constructor. You should call findViewById after view has inflated. Their is a method you can override onFinishInflate

score 2 · Answer 19 · answered Nov 26 '17 at 19:20

2

My case is none like above, no solutions worked. I assume my view was too deep into layout hierarchy. I moved it one level up and it was not null anymore.

answered Nov 26 '17 at 19:20

Deividas Strioga

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I have the same problem, one level higher can also be found.. that's quite annoying and I'd like to know why it's happening as I can't make my menu like I want it to – NaturalBornCamper Dec 23 '17 at 17:17
Well deep layout hierarchies are anti pattern, almost always there is a cleaner solution. Are you talking about overflow menu in toolbar, or navigation drawer? – Deividas Strioga Dec 25 '17 at 12:03
Navigation drawer, I already posted another question actually, except that adding a menu item inside a group is not working, just adds it at the end of all the items: https://stackoverflow.com/questions/47955376/get-subview-of-loaded-view-group-inside-a-drawer/47955507#47955507 – NaturalBornCamper Dec 25 '17 at 20:27

Suragch · Answer 20 · 2016-01-19T14:44:44.613

In my case I had inflated the layout but the child views were returning null. Originally I had this:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_history);

    footerView = ((LayoutInflater) getApplicationContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE)).inflate(R.layout.listview_footer, null, false);
    pbSpinner = (ProgressBar) findViewById(R.id.pbListviewFooter);
    tvText = (TextView) findViewById(R.id.tvListviewFooter);
    ...
}

However, when I changed it to the following it worked:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_history);

    footerView = ((LayoutInflater) getApplicationContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE)).inflate(R.layout.listview_footer, null, false);
    pbSpinner = (ProgressBar) footerView.findViewById(R.id.pbListviewFooter);
    tvText = (TextView) footerView.findViewById(R.id.tvListviewFooter);
    ...
}

The key was to specifically reference the already inflated layout in order to get the child views. That is, to add footerView:

footerView.findViewById...

score 1 · Answer 21 · answered Oct 24 '15 at 20:52

INFLATE THE LAYOUT !! (which contains the id)

In my case findViewById() returned null, because the layout in which the element was written, was not inflated...

Eg. fragment_layout.xml

<ListView
android:id="@+id/listview">

findViewById(R.id.listview) returned null, because I had not done inflater.inflate(R.layout.fragment_layout, ..., ...); before it.

Hope this answer helps some of y'all.

score 1 · Answer 22 · edited Dec 13 '18 at 03:18

1

It crashed for me because one of fields in my activity id was matching with id in an other activity. I fixed it by giving a unique id.

In my loginActivity.xml password field id was "password". In my registration activity I just fixed it by giving id r_password, then it returned not null object:

password = (EditText)findViewById(R.id.r_password);

edited Dec 13 '18 at 03:18

Vega

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answered Dec 13 '18 at 02:09

Jageloo Yadav

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score 0 · Answer 23 · answered Apr 11 '14 at 15:49

0

In my experience, it seems that this can also happen when your code is called after OnDestroyView (when the fragment is on the back stack.) If you are updating the UI on input from a BroadCastReceiver, you ought to check if this is the case.

answered Apr 11 '14 at 15:49

Tad

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score 0 · Answer 24 · edited May 23 '17 at 11:33

0

findViewById also can return null if you're inside a Fragment. As described here: findViewById in Fragment

You should call getView() to return the top level View inside a Fragment. Then you can find the layout items (buttons, textviews, etc)

edited May 23 '17 at 11:33

Community

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answered Oct 27 '16 at 02:26

technocrat

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score 0 · Answer 25 · answered Jul 27 '18 at 05:24

In my case, findViewById returned null when I moved the call from a parent object into an adapter object instantiated by the parent. After trying tricks listed here without success, I moved the findViewById back into the parent object and passed the result as a parameter during instantiation of the adapter object. For example, I did this in parent object:

 Spinner hdSpinner = (Spinner)view.findViewById(R.id.accountsSpinner);

Then I passed the hdSpinner as a parameter during creation of the adapter object:

  mTransactionAdapter = new TransactionAdapter(getActivity(),
        R.layout.transactions_list_item, null, from, to, 0, hdSpinner);

score 0 · Answer 26 · edited Mar 13 '19 at 10:35

I was facing a similar problem when I was trying to do a custom view for a ListView.

I solved it simply by doing this:

public View getView(int i, View view, ViewGroup viewGroup) {

    // Gets the inflater
    LayoutInflater inflater = LayoutInflater.from(this.contexto);

    // Inflates the layout
    ConstraintLayout cl2 = (ConstraintLayout) 
    inflater.inflate(R.layout.custom_list_view, viewGroup, false);

    //Insted of calling just findViewById, I call de cl2.findViewById method. cl2 is the layout I have just inflated. 
     TextView tv1 = (TextView)cl2.findViewById(cl2);

score 0 · Answer 27 · answered May 31 '20 at 10:48

Ways to debug and find the issue:

Comment out all findViewById in your activity.
Comment out everything except onCreate and setContentView
Run the project and see if any layout is set

In my case, I was using activity_main.xml in both my app module and also my library module. So when I performed the above steps, instead of the layout which I designed in the library, the layout inside app module was inflated.

So I changed the activity_main.xml file name to activity_main_lib.xml.

So make sure you do not have any duplicate layout names in your whole project.

AtomicBoolean · Answer 28 · 2022-02-03T15:06:08.617

0

The issue for me was that I had two layouts with the same file name activity_main.xml. (The layouts were in different libraries but in the same app) The issue was solved by renaming one of them to a unique name.

edited Feb 03 '22 at 15:06

answered Feb 03 '22 at 15:00

AtomicBoolean

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score 0 · Answer 29 · answered Feb 24 '22 at 08:38

0

For me it returned null because the given control was (programmatically) hidden. When I put a condition to call findViewByID(id) only when the control is visible, it started working again.

answered Feb 24 '22 at 08:38

Attila

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score 0 · Answer 30 · answered Jul 25 '22 at 09:15

0

For me it was only null when using Evaluate Expression or the Debug Watch View of the IDE.

answered Jul 25 '22 at 09:15

Jennifer Kiesel

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user1506104 · Answer 31 · 2023-02-18T00:18:49.723

0

I had the same .xml file in two seprate modules that had the same view id in it.

app/src/main/res/layout/header.xml
supportModule/src/main/res/layout/header.xml

Both layouts had TextViews with the same id @+id/tv_prompt.

My TextView tvPrompt = findViewById(R.id.tv_prompt); always returned null. I had to rename my other xml file to header_main.xml to fix the issue.

edited Feb 18 '23 at 00:18

answered Jan 24 '23 at 12:26

user1506104

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score 0 · Answer 32 · answered Jul 26 '23 at 13:55

I am using Flamingo 2022.2.1 Patch 2 (Build #AI-222.4459.24.2221.10121639, built on May 12, 2023)

In my case this was happening because for some reason I had TWO activity_main.xml objects under my layout folder. One was "Activity_main.xml" and the other was "(v31)activity_main.xml".

Of course, (v31)activity_main.xml didn't contain the button I was trying to use with findViewById and as a result it came back null.

I've no idea where "(v31)activity_main.xml" came from, but after I did a safe delete and removed it, the problem was gone.

Hope this helps someone in the future!

score -1 · Answer 33 · answered May 24 '16 at 17:51

-1

My fix was to just clean the project.

answered May 24 '16 at 17:51

Liangjun

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score -1 · Answer 34 · answered Oct 06 '17 at 06:05

-1

I've tried all of the above nothing was working.. so I had to make my ImageView static public static ImageView texture; and then texture = (ImageView) findViewById(R.id.texture_back); , I don't think it's a good approach though but this really worked for my case :)

answered Oct 06 '17 at 06:05

Tabish

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sorry, i think static view is bad idea – vuhung3990 Jun 25 '18 at 09:29

findViewByID returns null

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