Objects First with Java: A Practical Introduction Using BlueJ (6th Edition)
6th Edition
ISBN: 9780134477367
Author: David J. Barnes, Michael Kolling
Publisher: PEARSON
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Expert Solution & Answer
Chapter 3, Problem 44E
Explanation of Solution
Given: The mail-system project.
To find: The steps to create an object of class MailServer and then create two objects of class MailClient and set the name of instance as sophie and juan. The name of the user in the MailClient should be “Sophie� and “Juan�. After that, invoke the method named sendMailItem of Sophie’s instance in order to send the message to the user named Juan.
Solution:
In order to create an object of MailServer class, it is necessary to right click on the MailServer class and then click on new MailServer(); and then click on “ok� button.
A rectangular box will appear on BlueJ indicating that it is an object.
Similarly, an object of another class named MailClient can be created.
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In this exercise, you are going to build on your Circleclass from the previous exercise.
You are going to add 2 method, areaDifference and perimeterDifference. Both methods take a doubleradius of a second circle and return the difference from the current circle.
For example, if you create a Circle object with a radius of 4 and call areaDifference(3), you will return the diffence between the area of a circle with radius 4 and the area of a circle with a radius of 3. perimeterDifferencewould be the same.
Make sure you create at least one Circle and test and print the results of your methods.
in java
In this exercise, you are going to build on your Circleclass from the previous exercise.
You are going to add 2 method, areaDifference and perimeterDifference. Both methods take a doubleradius of a second circle and return the difference from the current circle.
For example, if you create a Circle object with a radius of 4 and call areaDifference(3), you will return the diffence between the area of a circle with radius 4 and the area of a circle with a radius of 3. perimeterDifferencewould be the same.
Make sure you create at least one Circle and test and print the results of your methods.
given: public class Circle{private double radius;public Circle(double theRadius){radius = theRadius;}// Add a method called area that returns the area of a circle// using Math.PIpublic double area(){return Math.PI*radius*radius;}// Add a method called perimeter that returns the perimeter of a// circle using Math.PIpublic double perimeter(){return Math.PI*2*radius;}}
Chapter 3 Solutions
Objects First with Java: A Practical Introduction Using BlueJ (6th Edition)
Ch. 3 - Prob. 1ECh. 3 - At what time (s) can a class diagram change? How...Ch. 3 - At what time(s) can an object diagram change? How...Ch. 3 - Write a definition of a field named tutor that can...Ch. 3 - Prob. 5ECh. 3 - Create a second NumberDisplay object with a limit...Ch. 3 - Select Show Code Pad from the View menu. Create a...Ch. 3 - What error message do you see in the Code Pad if...Ch. 3 - What error message do you see in the Code Pad if...Ch. 3 - What happens when the setValue method is called...
Ch. 3 - Prob. 11ECh. 3 - Prob. 12ECh. 3 - Which of the following expressions return...Ch. 3 - Write an expression using boolean variables a and...Ch. 3 - Write an expression using boolean variables a and...Ch. 3 - Consider the expression (a && b). Write an...Ch. 3 - Does the getDisplayValue method work correctly in...Ch. 3 - Prob. 18ECh. 3 - In Exercise 2.79 you were asked to investigate...Ch. 3 - Explain the modulo operator. You may need to...Ch. 3 - What is the result of the expression 83?Ch. 3 - Try out the expression in the Code Pad. Try other...Ch. 3 - Prob. 23ECh. 3 - Prob. 24ECh. 3 - Explain in detail how the increment method works.
Ch. 3 - Rewrite the increment method without the modulo...Ch. 3 - Open the clock-display project and create a...Ch. 3 - Prob. 28ECh. 3 - Prob. 29ECh. 3 - Prob. 30ECh. 3 - Look at the second constructor in C1ockDisplay's...Ch. 3 - Prob. 32ECh. 3 - Given a variable Printer p1; which currently holds...Ch. 3 - Open the house project from Chapter 1 and review...Ch. 3 - Prob. 35ECh. 3 - Does the Picture class contain any internal method...Ch. 3 - Remove the following two statements from the draw...Ch. 3 - Prob. 38ECh. 3 - Prob. 39ECh. 3 - Assume a class Tree has a field of type Triangle...Ch. 3 - Prob. 41ECh. 3 - Open the mail-system project, which you can find...Ch. 3 - Prob. 43ECh. 3 - Prob. 44ECh. 3 - Open the editor for the MailClient class and set a...Ch. 3 - Step one line forward in the execution of the...Ch. 3 - Prob. 47ECh. 3 - Prob. 48ECh. 3 - Prob. 49ECh. 3 - Set a breakpoint in the first line of the sendMai1...Ch. 3 - Use a combination of code reading, execution of...Ch. 3 - Use the debugger to investigate the clock-display...Ch. 3 - Prob. 53ECh. 3 - Prob. 54ECh. 3 - Prob. 55ECh. 3 - Describe the changes that would be required to the...Ch. 3 - Write the code for the timeTick method in...Ch. 3 - Discuss whether the current design of the...Ch. 3 - Challenge exercise In the current design of...
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