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    lt FrameLayout       gt       lt some package MyCustomView       gt        lt LinearLayout      gt           lt TextView                 android id    id txtLat    gt                   lt  LinearLayout gt   lt  FrameLayout gt    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

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Set the activity content from a layout resource  ie  setContentView R layout basicXml

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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

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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

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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

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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

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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

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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

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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     lt include layout   layout content main    gt    When I added that to activity main xml  no more NullPointer

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

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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

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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

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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    lt 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  gt                 lt include         layout   layout retry button          android visibility  gone    gt    Child view  retry button     lt 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  gt     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    lt 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  gt                 lt include         layout   layout retry button          android id    id retry          android visibility  gone    gt    Fixed child    lt 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  gt

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My fix was to just clean the project

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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

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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

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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

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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

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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   lt ListView android id    id listview  gt    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

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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

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Override protected void onStart                 use findViewById   here instead of in onCreate

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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

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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

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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

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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

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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

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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

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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

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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

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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

[android] findViewByID returns null

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