Android dynamic background

I am somewhat of a new android developer and have a question regarding changing the background dynamically at runtime.

What I want to do is set a background color in a LinearLayout Tag, and later change that background color in my activity class. This code below is not working. Am I missing something or is this the wrong approach for trying to change the background color in a linear layout

LinearLayout lv = (LinearLayout)findViewById(R.id.ChoiceLayout);
 lv.setBackgroundColor(0x000080);
 

Thanks in advance

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