Java Reference
In-Depth Information
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Javadoc also has its own home page on the Javasoft web site at
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.
Summary
In this chapter you have seen all of the basic types of variables available in Java. The discussion of
boolean
variables will be more meaningful in the context of the next chapter since their primary use is
in decision making and modifying the execution sequence in a program.
The important points you have learned in this chapter are:
The integer types are
byte
,
short
,
int
, and
long
, occupying 1, 2, 4, and 8 bytes
respectively.
❑
Variables of type
char
occupy 2 bytes and can store a single Unicode character code.
❑
Integer expressions are evaluated using 64-bit operations for variables of type
long
, and using
32-bit operations for all other integer types. You must therefore add a cast for all assignment
operations storing a result of
type
byte
,
short
, or
char
.
❑
A cast will be automatically supplied where necessary for
op
= assignment operations.
❑
The floating-point types are
float
and
double
, occupying 4 and 8 bytes respectively.
❑
Values that are outside the range of a floating-point type are represented by a special value
that is displayed as either
Infinity
or -
Infinity
.
❑
Where the result of a floating point calculation is indeterminate, the value is displayed as
NaN
.
Such values are referred to as not-a-number.
❑
Variables of type
boolean
can only have either the value true or the value false.
❑
The order of execution of operators in an expression is determined by their precedence. Where
operators are of equal precedence, the order of execution is determined by their associativity.
❑
Exercises
1.
Write a console program to define and initialize a variable of type
byte
to 1, and then successively
multiply it by 2 and display its value 8 times. Explain the reason for the last result.
2.
Write a console program to declare and initialize a
double
variable with some value such as
1234.5678. Then retrieve the integral part of the value and store it in a variable of type
long
,
and the first four digits of the fractional part and store them in an integer of type
short
.
Display the value of the
double
variable by outputting the two values stored as integers.
