When to call findViewById in an Activity

Question

I am encountering the following issue. I have the following lines of code :

Spinner domainSpinner = (Spinner) findViewById(R.id.domain);
domainSpinner.setVisibi         


        

Answer 1

You should always initialise your views on the OnCreate method in an activity to make sure the view exists when you want to reference it. Like below:

private Spinner domainSpinner;

@Override
    protected void onCreate(final Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        domainSpinner = (Spinner) findViewById(R.id.domain);
    }

Let me know if this helps!

UPDATE: If you need to use the variable outside of the on create method, then declare a global variable and still initialise it on create, then use it where needed.

Answer 2

You can try this. Make sure the domainSpinner is initialized on the Main Thread. Also add a condition for setting visibility only when domainSpinner is not equal to null.

Handler mainHandler = new Handler(context.getMainLooper());
mainHandler.post(new Runnable() {

    @Override
    public void run() {
        Spinner domainSpinner = (Spinner) findViewById(R.id.domain);
        if(domainSpinner!=null) {
           domainSpinner.setVisibility(View.VISIBLE);
        }
    }
});