findViewByID returns null

user_393827 0
Viewed 202626

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.

android-view android
32 Answers

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.

user_62811600

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);
user_19428050

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)

user_11349610

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);
user_53223370

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);
user_111964640

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.

user_77107390

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.

user_15490460

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.

user_113449360

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

user_145772030

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 :)

user_83114410
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