Don’t implicitly unbox the primitives, use the correct parser method

Discovered by FindBugs.
Use autoboxing instead of creating new Integer objects

Discovered by FindBugs.
Don’t iterate over keys and look up the values, iterate over entries

Discovered by FindBugs.
Don’t use String concatenation in loops, use a StringBuilder

Discovered by FindBugs.
Declare constants as static

Discovered by FindBugs.
Remove unused fields

Discovered by FindBugs.
Remove unused parameter

Discovered by FindBugs.