Java Reference
In-Depth Information
Display 5.3
Another Class with a
main
Added
(part 2 of 2)
37
public static double
toCelsius(
double
degreesF)
38 {
39
40
return
5*(degreesF - 32)/9;
41 }
42
public static void
main(String[] args)
43 {
44
double
degreesF, degreesC;
45
46 Scanner keyboard =
new
Scanner(System.in);
47 System.out.println("Enter degrees Fahrenheit:");
48 degreesF = keyboard.nextDouble();
49
50 degreesC = toCelsius(degreesF);
51
52 Temperature temperatureObject =
new
Temperature(degreesC);
53 System.out.println("Equivalent Celsius temperature is"
54 + temperatureObject.toString());
55 }
56 }
Because this is in the definition of the
class
Temperature,
this is equivalent to
Temperature
.
toCelsius(degreesF).
Because
main
is a static method,
toString
must have a
specified calling object such as
temperatureObject.
Sample Dialogue
Enter degrees Fahrenheit:
212
Equivalent Celsius temperature is 100.0 C
Self-Test Exercises
1. Is the following legal? The class
RoundStuff
is defined in Display 5.1 .
RoundStuff roundObject =
new
RoundStuff();
System.out.println("A circle of radius 5.5 has area"
+ roundObject.area(5.5);
2. In Display 5.1, we did not define any constructors for the class
RoundStuff
. Is
this poor programming style?
3. Can a class contain both static and nonstatic (that is, regular) methods?
4. Can you invoke a nonstatic method within a static method?
5. Can you invoke a static method within a nonstatic method?
6. Can you reference an instance variable within a static method? Why or why not?
