some simple vim commands

undo : u
redo : Ctrl+R
delete: d<number of lines to delete>d
copy : y<number of lines to copy>y
indent: <number of lines to indent>>>

Why call system.out.flush()?

following question in stackoverflow addresses this question very well.

http://stackoverflow.com/questions/7166328/when-why-to-call-system-out-flush-in-java