Pre- and postincrement in Java

Question

I just wanted to create a little Java-Puzzle, but I puzzled myself. One part of the puzzle is:

What does the following piece of code do:

Answer 1

The output is 9 (try it)

int i = 1;
i += ++i + i++ + ++i;

becomes

i = 1 + 2 + 2 + 4