In Java int and String conversion

int converted to a String

• Use the static method of Integer
  • Integer.toString (int num); a null value will throw a NullPointerException
• Use the static method of String
  • String.valueOf (int num); return null "null"
• num + ""; produced two string objects, the slowest

String into int

• Interger.parseInt (String str) static method does not produce objects
• Integer.valueOf (String str) .intValue (); generating an object corresponding to a new Interger.valueOf (String str)