Java Reference
In-Depth Information
}
As you can see, the new version is more compact and does not use an
if-else
construct.
However, the rewrite only applies when one of two different values is assigned to the same
variable based on the validity of a condition.
2.8 Summary
The chapter presented an introduction to Java programming. Using an integrated devel-
opment environment, such as NetBeans, simplifies the development process. NetBeans not
only helps us identify compiler errors instantly, but also allows us to execute our program
line by line and monitor how the variables change (a.k.a., debug the program).
The cornerstones of any program are the variables. They can be thought as the “memory”
of the program. Throughout the execution of the program, we use variables to save important
data. Java allows us to create variables that store characters, integers, reals, and strings,
among others. Note that every type has a restriction. For example, we cannot store a number
that is bigger than three billion inside a variable of type
int
. Similarly, we can only store a
finite number of different real numbers inside a variable of type
double
and loss of precision
is common. Sometimes, the value of a variable can be supplied from the keyboard. In other
cases, the value of a variable can be the result of some computation. As we saw, we can
even assign a variable to be equal to a random number.
Managing the control flow is an important part of every program. For example, some-
times we want to branch our program based on the value of a condition. In this case, we
can use an
if
statement. Similarly, we can use a
switch
statement when we want to check
if a variable is equal to one of several values, where a
switch
statement can only be used
on integers, characters, and strings. A conditional operator is used when we want to assign
one of two values to a variable based on the validity of a Boolean condition.
2.9 Syntax
⇒
Declares the variable
i
to be an integer.
int i
i=3
⇒
Assignsthevalue3tothevariable
i
.
double d
⇒
Declares the variable
d
to be a double.
d = 32.22
⇒
Assigns the value 32.22 to the variable
d
.
char c
⇒
Declares the variable
c
to be a character.
c='a'
⇒
Assigns the value
a
to the variable
c
.
'
'
long l = 2342412L
⇒
Declares the variable
l
to be of type
long
and assigns the
value 2342412 to it.
float f = 22432.222F
⇒
Declares the variables
f
to be of type
float
and assigns
the value 22432.222 to it.
