(1)The following is invalid. Why?
public void myMethod(int one) {
return (one + one);
}
(2)Which of the following methods are class methods?
public static void one( ) { . . . }
publicinttwo ( ) { . . . }
private static int three ( ) { . . . }
public float four ( ) { . . . }
(3)If the data member feeRate is declared private, is the following statement valid? Why?
FeeCharge = currencyChanger.feeRate;
(4)Do Exercise 4 of Chapter 4 (page 183).
Determine the output of the given program.
Hint: draw the state of memory diagram to solve the problem.
/*
Chapter 4 Exercise 4
*/
import javabook.*;
class Exercise4_4
{
public static void main( String[ ] args )
{
Question4 q4;
q4 = new Question4( );
q4.start( );
}
}
class Question4
{
private int x, y, z;
private MainWindow mainWindow;
private OutputBoxoutputBox;
public void start ( )
{
intx, y;
setup();
x = y = 10;
modify(x, y);
printout();
}
private void setup( )
{
mainWindow = new MainWindow( );
outputBox= new OutputBox(mainWindow);
mainWindow.setVisible( true );
outputBox.setVisible( true );
x = 100;
y = 200;
z = 300;
}
private void modify( int x, int y)
{
z = x + y;
x = z;
y = 2 * z;
}
private void printout( )
{
outputBox.printLine("x = " + x);
outputBox.printLine("y = " + y);
outputBox.printLine("z = " + z);
}
}
(5)Write an application that computes the area of a donut region (the shaded area) given the radius of the inner and outer circles.
Guidelines:
1,Define an instantiable Donut class which accepts the radius of the inner and outer circles when creating the Donut object. The Donut class should include the following:
-
private instance variable innerRadius
-
private instance variable outerRadius
-
a proper constructor
-
private instance method circleArea with one parameter radius. The method returns the area of the circle of specified radius.
-
public instance method getDonutArea with no parameter. The method returns the area of the donut by using the method circleArea.
2,Write an application that accepts the inner radius and outer radius of the donut from the user, and output the area of the donut.
(6.)
Refer to Ex 13 in chapter 4. Write an instantiable WeightConverter class. An instance of this class is created by passing the gravity of an object relative to the earth’s gravity. For example, the moon’s gravity is approximately 0.167 of the earth’s gravity, so we create a WeightConverter instance for the moon as
WeightConverter
moonWeight;
moonWeight = new WeightConverter(0.167);
An instance of this class can also be created without specifying the relative gravity, but assigned at a later time as
WeightConverter
PlanetWeight;
planetWeight = new WeightConverter( );
. . .
planetWeight.setFactor(1.3);
To compute how much you wiegh on the moon, you pass your wieght on earth to the convert method as
yourMoonWeight = moonWeight.convert( 160 );
Define the WeightConverter class. Write an application that inputs the user’s weight on earth and outputs his/her weight on Mercury, Venus, Jupiter, Saturn and a planet of the user’s choice. (See Exercise 12 of chapter 3, page 132) Use the values in the table below:
Planet
Multiply the earth Weight by
Mercury
0.4
Venus
0.9
Jupiter
2.5
Saturn
1.1
Your planet
input your own factor
Guidelines:
A demonstration of the program is given as WeightConverterMain.class and WeightConverter.class in folder apLab7. You may also refer to the CurrencyConverter example in chapter 4.
Deadline:
You have to finish Question 6 BEFORE the next lab session and your program will be inspected in the next lab session.
|
