SCJA - Fundamental object oriented concepts 1.1

In my next few blogs i'll be preparing notes on each objective in the Sun Certified Java Associate Beta exam, which i'm planning to take on July 1st.

1.1)Describe, compare, and contrast primitives (integer, floating point, boolean, and character), enumeration types, and objects
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The first important step is to break down the classification of integral types:

---------Integral -> (Integer)byte, short,int,long(Character) char
Primitive Types in Java -----------Float ->Float,Double
---------Boolean --> boolean

Primitive data types represent a range of values in the programming language. If you want to represent these types as objects, then there are corresponding wrapper types viz. Integer,Float,Long etc.

The range of primitive data type is worth memorizing, (I used the table from Mughal and Rassmussen)

ENUMERATION TYPES:

The enumerated type is a new introduction in J2SE 5.0 . Its a type whose legal values consist of a set of constants:

Eg: enum cars(MCLAREN,RENAULT,FERRARI,TOYOTA,BMW,HONDA,SAUBER,JORDAN);

You would use enum types whenever you would want to represent a fixed setof constants (known to you at compile type). Unlike C++ enum in Java is a Class!! Not convincing enough right?! Ok Check this out:

public enum FormulaTeams{
MCLAREN (Raikkonen,Montoya);
RENAULT (Alonso,Fisichella);
FERRARI (Schumacher,Barrichelo);
TOYOTA (Trulli,Schumacher);
BMW (Webber,Heidfeld);
HONDA (Button,Sato);
SAUBER(Villnueave,Massa);
JORDAN (Karthikeyan,Montiero);

private final String driver1;
private final String driver2;

//Note that the constructor is private, it has to be!
FormulaTeams(String driver1,String driver2)
{
this.driver1=driver1;
this.driver2=driver2;
}

public String d1() {return driver1;}
public String d2() {return d2;}

}

public static void main(String args[])
{
for(FormulaTeams f: f.values()){
System.out.println("Standings at the End of 2005");
System.out.println("Driver 1"+f.d1()+"Driver 2"+f.d2());
}
}

Pretty cool huh? try doing the same in 1.4 (I know you'll be using a data structure from java.util.*) . Ok you'll find a better more Object Oriented example here:
http://java.sun.com/docs/books/vmspec/2nd-edition/html/Concepts.doc.html#24465


}




A Few Caveats:

a) Integer datatypes are signed integers and are represented by their 2's complement.
b) character values are all unsigned integers that denote 2^16 characters in the unicode character set.
c)Floating point representation can be 32 or 64 bit in width, due to size for representation being finite, most results of floating point computations are finite. To ensure consistency for these approximations across all JVM implementations you can use the "strictfp " modifier.
http://java.sun.com/docs/books/vmspec/2nd-edition/html/Concepts.doc.html#24465
d)There's one limitation of enum types: although enum types are classes, you cannot define a hierarchy of enums. In other words, it's not possible for one enum type to extend another enum type (That wouldn't make sense anyhow)