To better understand what an inner class is, I'd suggest reading Sun's Java Tutorial Trail on Inner Classes.
Thanks for the reminding and answer!
I have read this tutorial before. The answer of my question can not be found directly from the tutorial.
Actually I want to ask why in this
if statement the outter class name
Test4 can be used to refer to the
flag. How can you know you can use this format to refer to a outter class's field variable? In which book or in which part of the sun tutorial can you find similar usage like
Test4.this.flag(I can not find a example like this in Sun's inner class tutorial)?