Data Types and Conditional Statements - Learning Java Through Games - page 17

TABLE 2 . 1 :

Java primitive types.

( Type ) ( Size ) ( Values )

1 byte -128 to 127

byte

short 2 bytes -32,768 to 32,767

int 4 bytes -2,147,483,648 to 2,147,483,647

long 8 bytes -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807

10 96 to 10 96

4 bytes −

float

10 384 to 10 384 8 bytes −

double

1bit

true of false boolean

2 bytes 0 to 65,535

char

letter. For example, the following code declares, sets, and prints the value of an integer
variable.

int i;
i=3;
System. out . println ( i ) ;

The first line declares the variable i to be of type integer. The second line assigns the
number 3 to the variable. The third line prints the value of the variable. The first two lines
can be combined as follows.

int i=3;

Note that several variables can be declared on the same line. For example, the following
is a valid statement.
int i=3, j =4;

However, we can define multiple variables in a single line only when all the variables are
of same type.
Note that a computer is not all powerful, that is, it cannot represent an arbitrary number.
For example, we all know that there are infinitely many real numbers, while the main
memory of a computer is finite. This is why Java defines primitive variable types that take
a fixed amount of memory. For example, the byte type can be used to store a small integer,
while the long type can be used to store up to a 19-digit integer. Most of the time, we want
to store an integer that is not very big (less than 10 digits) and we will use the type int .
Note that most types allow for both negative and positive integers to be stored. Usually,
the first bit of the binary representation of a number indicates if the number is positive or
negative.
There is a special syntax that is needed in Java to represent a long number. The letter
“L” must be appended to the end of the number. For example, a variable of a long type
canbedefinedasfollows.
long ssn = 999333222L;

A float and a double must have a decimal point. For example, the number 3 is perceived
as an int , while the number 3.0 is considered a double .A float must also have the letter
F after it. Here is an example of declaring a variable of type float .
float pi = 3.1415F;

A byte is a number that is represented by a single byte (8 bits). A hexadecimal number
can be specified by using the 0x prefix. For example, consider the following code snippet.

byte x=0x2F;
System. out . println (x) ;