Triangle using nested loops:
http://javablogx.blogspot.com/2014/02/dr...
Hollow Triangle:
http://javablogx.blogspot.com/2014/10/ho...
Floyds Triangle:
http://www.javacodex.com/Math-Examples/F...
Pascal Triangle:
http://www.javacodex.com/Math-Examples/P...
Like this?
http://ideone.com/4rBrG4