Converted to Junit4
Made final fields static
Use System.arraycopy for efficiency
Avoid creating new Boolean (Boolean.valueOf is better)
Hide utility class constructor
Inefficient String buffering
Iterating over entrySet() is more efficient
Iterating over entrySet() is more efficient (additional optimisation)
Avoid String concatenation within a loop
Avoid inefficient Number constructor, valueOf not required since auto-boxing covers use case
Converting inner classes to static inner classes
Removing unnecessary boxing
Removing unnecessary local before return
Removed unnecessary case change (just use ignore case)
Various fixes (redundant variables, improved iteration etc)
String.indexOf(char) is faster than String.indexOf(String)
Applied String.contains() for better semantics
Avoid == with String values
Check return value from attempted file creation
Remove unnecessary boxing
Remove infinite recursive loop
equals() comparing different types
Correcting double assignments (highlighted missing assignment)