Java Reference
In-Depth Information
Sample Run: (In this sample run, the user input is shaded.)
Enter first name, last name, age, and weight separated by spaces.
Sheila Mann 23 120.5
Name: Sheila Mann
Age: 23
Weight: 120.5
The preceding program works as follows: The statements in Lines 1 to 4 declare the variables
firstName
and
lastName
of type
String
,
age
of type
int
,and
weight
of type
double
.
The statement in Line 5 is an output statement and tells the user what to do. (Such output
statements are called prompt lines.) As shown in the sample run, the input to the program is:
Sheila Mann 23 120.5
The statement in Line 6 reads and assigns the string
Sheila
to the variable
firstName
;
the statement in Line 7 skips the space after
Sheila
and reads and assigns the string
Mann
to the variable
lastName
. Next, the statement in Line 8 skips the blank after
Mann
and
reads and stores
23
into the variable
age
. Similarly, the statement in Line 9 skips the blank
after
23
and reads and stores
120.5
into the variable
weight
.
The statements in Lines 10, 11, and 12 produce the third, fourth, and fifth lines of the
sample run.
VARIABLE INITIALIZATION
Remember, there are two ways to initialize a variable: by using the assignment statement
and by using a read statement. Consider the following declaration:
int
feet;
int
inches;
Consider the following two sets of code:
(a)
feet = 35;
inches = 6;
System.out.println("Total inches = " + (12 * feet + inches));
(b)
System.out.print("Enter feet: ");
feet = console.nextInt();
System.out.println();
System.out.print("Enter inches: ");
inches = console.nextInt();
System.out.println();
System.out.print("Total inches = " + (12 * feet + inches));
In (a),
feet
and
inches
are initialized using assignment statements, and in (b), these
variables are initialized using input statements. However, each time the code in (a)
executes,
feet
and
inches
are initialized to the same value, unless you edit the source
code, change the value, recompile, and run. On the other hand, in (b), each time the
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