1. Kenia Álava

2. There are a bunch of guys that are used very often in programming and requires special
treatment. Types can be considered as "primitive", the reason for this special treatment is
that to create a new object, a simple variable small, not efficient. To these primitive types,
Java uses the technique used in C and C + +, that is, instead of creating the new variable
creates a variable "automatic" is not a reference.
Java determines the size of each primitive type. These sizes do not change from one
machine to another architecture. This invariability of the sizes is one of the reasons of
portability java.
Kenia Álava

3. Defaults primitive members
When a primitive data type as a member of a class, Java guarantees that you will be
assigned a default value if it fails to boot:
The defaults are only the values that Java guarantees when the variable is used as a class
member. This ensures that the member variables of primitive type always be initialized
(something C + + does not do), reducing a source of potential errors. However, this initial
value may not be correct or even legal for the program you are writing. It is best to always
initialize variables explicitly.
This warranty does not apply to initialize local variables, those that are not class fields.
Kenia Álava