设置一个值是否比检查存在性和仅设置不存在（例如在此Android / Java代码中）要快？

Question

Example:

That code is run each time, when the listAdapter requests a new row:

if (textViewTitle != null)
          textViewTitle.setTypeface(Controller.getInstance().widgetSettings.getBoldTypeface());

vs.

if (textViewTitle != null 
    && textViewTitle.getTypeface() != null
    && textViewTitle.getTypeface().equals(Controller.getInstance().widgetSettings.getBoldTypeface()))
          textViewTitle.setTypeface(Controller.getInstance().widgetSettings.getBoldTypeface());

Answer 1

It depends entirely on how costly the creation and equality operation are. It should be trivial to benchmark as needed if performance is that important.

If performance isn't so important, then the former is far more readable, and conveys just as much information about the intention of the code as the latter.

Answer 2

确保textViewTitle始终引用某些内容，因此您无需检查其是否存在。

Answer 3

Maybe setTypeface is more than just setting a property, for example causes redrawing? In this case you would like to avoid calling it unless it changes something.
BTW in second code if original typeface is not set, it won't be set. I'm not sure if it's intended.