Fix boxing of already boxed values

This is a useless operation since any boxed value will first be
auto-unboxed before boxing the value again. If done inside an inner loop
such code may cause performance problems.
Fix manual array to collection copy
Fix redundant String constructor call
Fix string concatenation in StringBuffer.append()

Such calls may profitably be turned into chained append calls on the
existing StringBuffer/Builder/Appendable, saving the cost of an extra
StringBuffer/Builder allocation.
Replace StringBuffer with String

These may be replaced with java.lang.String expressions which results in
simpler and possibly more efficient code
Fix pointless aithmetic expressions
Fix unnecessary boxing/unboxing
Remove redundant local variables
Remove continue and return
Remove unecessary semicolon
Fix unnecessary bitwise operations