Data encoding

1. Primitive datatypes in Java are:

• char that represents unicode character and are encoded with 2 octects, eg. char c='X';
• int encoded with 4 octets and that corresponds to integers with:
  • arithmetic operators (+,-,/,%) and
  • relational operators (==,!=,<,<=...)
• long are also integer values but use 8 octets.
• float that represents real numbers and are encoded with 4 octets, e.g. float pi=3.13F;
• double that represents double precision real numbers and are encoded with 8 octets
• byte that corresponds to 1 octet
• boolean represents true/false values and are encoded with 1 octet

2. All the primitive datatype are associated to a corresponding class called wrapper for the type, e.g. Char for char, Integer for int, etc. The classes then propose all program to manipulate the primitive value as illustrated below:

String  str = Integer.toString( 12 );
int     val = Integer.parseInt(str);
Integer obj = Integer.valueOf(val);
System.out.println(obj.compareTo(new Integer(1)));
// -1 = inferior, 0 = equal, 1 = superior