Question

Sorry in advance in case this is a stupid question!

I was playing around with a couple of things in Android, and I was experimenting with changing elements at run time which were specified in the xml file.

Button buttonSetup = (Button) findViewById(R.id.buttonSetup);
buttonSetup.setTextSize(40);

However, I noticed that this crashed the application if you make the changes before –

setContentView(R.layout.main);

What is the reason for this? (Sorry if I’m missing something obvious! I think my brain has gone into hibernation for Winter!)

I had thought it would be best practice to alter elements before setContentView, so that if you alter a lot of elements (say half a dozen or so attributes over half a dozen elements) it is not obvious to the user with things changing on screen.

Thanks!

Answer 1

Easy answer:

Your xml-Layout is inflated by calling setContentView.
Before you haven’t inflated it, the Activity doesn’t know about the XML.

You can manually inflate a View with this code:

LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
LinearLayout myLayout = (LinearLayout) inflater.inflate(R.layout.nameOfXML, null);

and later set the View to this inflated layout with

setContentView(myLayout);