Java Reference
In-Depth Information
Self-Test Exercises
10. Which of the following may be used as variable names in Java?
rate1, 1stPlayer, myprogram.java, long,
TimeLimit, numberOfWindows
11. Can a Java program have two different variables named
number
and
Number
?
12. Give the declaration for two variables called
feet
and
inches
. Both variables are
of type
int
and both are to be initialized to zero in the declaration.
13. Give the declaration for two variables called
count
and
distance
.
count
is of type
int
and is initialized to zero.
distance
is of type
double
and is initialized to
1.5
.
14. Write a Java assignment statement that will set the value of the variable
distance
to the value of the variable
time
multiplied by
80
. All variables are of type
int
.
15. Write a Java assignment statement that will set the value of the variable
interest
to the value of the variable
balance
multiplied by the value of the variable
rate
.
The variables are of type
double
.
16. What is the output produced by the following lines of program code?
char
a, b;
a = 'b';
System.out.println(a);
b = 'c';
System.out.println(b);
a = b;
System.out.println(a);
Assignment Compatibility
As a general rule, you cannot store a value of one type in a variable of another type.
For example, the compilers will object to the following:
int
intVariable;
intVariable = 2.99;
The problem is a type mismatch. The constant
2.99
is of type
double
and the variable
intVariable
is of type
int
.
There are some special cases where it is permitted to assign a value of one type to a
variable of another type. It is acceptable to assign a value of an integer type, such as
int
, to a variable of a floating-point type, such as the type
double
. For example, the
following is both legal and acceptable style:
assigning
int
values
to
double
variables
double
doubleVariable;
doubleVariable = 2;
The preceding will set the value of the variable named
doubleVariable
equal to
2.0
.