android compiler query

In order to trace some variables in my code I have inserted a line to write the variable name and value to a file. It seems that when I select 'Clean' to build the app sometimes a file which has had changes to the code is not recompiled unless I close and save it first. This mystery has only just appeared开发者_StackOverflow社区 and I am wondering if there is an option somewhere that has been accidentally changed. Does the compiler perhaps only recompile bits of the code in some fashion? Any ideas?

Not sure about this, I've never faced it before.

However, a good common practice Always save your files (Ctrl+S or Ctrl+Shift+S) before doing anything else)