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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Question
Chapter 2, Problem 38E
Program Plan Intro
Question reference:Â Refer to Chapter 2, Exercise 2.38 to modify the method named printTicket of the class TicketMachine.
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Whentheuserenters!!,themostrecentcommandinthehistoryisexecuted.In the example above, if the user entered the command:
Osh> !!
The ‘ls -l’ command should be executed and echoed on user’s screen. The command should also be placed in the history buffer as the next command.
Whentheuserentersasingle!followedbyanintegerN,theNthcommandin the history is executed. In the example above, if the user entered the command:
Osh> ! 3
The ‘ps’ command should be executed and echoed on the user’s screen. The command should also be placed in the history buffer as the next command.
Error handling:
The program should also manage basic error handling. For example, if there are no commands in the history, entering !! should result in a message “No commands in history.” Also, if there is no command corresponding to the number entered with the single !, the program should output "No such command in history."
Activity No.
Activity
Time (weeks)
Immediate Predecessors
1
Requirements collection
3
2
Requirements structuring
4
1
3
Process analysis
3
2
4
Data analysis
3
2
5
Logical design
50
3,4
6
Physical design
5
5
7
Implementation
6
6
c. Using the information from part b, prepare a network diagram. Identify the critical path.
2. UNIX Shell and History Feature [20 points]
This question consists of designing a C program to serve as a shell interface that
accepts user commands and then executes each command in a separate process. A
shell interface gives the user a prompt, after which the next command is entered.
The example below illustrates the prompt osh> and the user's next command:
cat prog.c. The UNIX/Linux cat command displays the contents of the file
prog.c on the terminal using the UNIX/Linux cat command and your program
needs to do the same.
osh> cat prog.c
The above can be achieved by running your shell interface as a parent process.
Every time a command is entered, you create a child process by using fork(),
which then executes the user's command using one of the system calls in the
exec() family (as described in Chapter 3). A C program that provides the general
operations of a command-line shell can be seen below.
#include
#include
#define MAX LINE 80 /* The maximum length command */
{
int…
Chapter 2 Solutions
Objects First with Java: A Practical Introduction Using BlueJ (6th Edition)
Ch. 2 - Create a TicketMachine object on the object bench...Ch. 2 - What value is returned if you get the machine's...Ch. 2 - Prob. 3ECh. 2 - Prob. 4ECh. 2 - Create another ticket machine for tickets of a...Ch. 2 - Prob. 6ECh. 2 - Does it matter whether we write...Ch. 2 - Prob. 8ECh. 2 - Put back the word public, and then check whether...Ch. 2 - From your earlier experimentation with the ticket...
Ch. 2 - Prob. 11ECh. 2 - Prob. 12ECh. 2 - Prob. 13ECh. 2 - Prob. 14ECh. 2 - In the following field declaration from the...Ch. 2 - Prob. 16ECh. 2 - Prob. 17ECh. 2 - To what class does the following constructor...Ch. 2 - How many parameters does the following constructor...Ch. 2 - Prob. 20ECh. 2 - Suppose that the class Pet has a field called name...Ch. 2 - Challenge exercise The following object creation...Ch. 2 - Compare the header and body of the getBalance...Ch. 2 - If a call to getPrice can be characterized as...Ch. 2 - If the name of getBalance is changed to getAmount,...Ch. 2 - Prob. 26ECh. 2 - Try removing the return statement from the body of...Ch. 2 - Compare the method headers of getPrice and...Ch. 2 - Do the insertMoney and printTicket methods have...Ch. 2 - Create a ticket machine with a ticket price of...Ch. 2 - How can we tell from just its header that setPrice...Ch. 2 - Complete the body of the setPrice method so that...Ch. 2 - Prob. 33ECh. 2 - Is the increase method a mutator? If so, how could...Ch. 2 - Prob. 35ECh. 2 - Write down exactly what will be printed by the...Ch. 2 - Add a method called prompt to the TicketMachine...Ch. 2 - Prob. 38ECh. 2 - What about the following version?
Ch. 2 - Prob. 40ECh. 2 - Add a showPrice method to the TicketMachine class....Ch. 2 - Create two ticket machines with differently priced...Ch. 2 - Modify the constructor of TicketMachine so that it...Ch. 2 - Give the class two constructors. One should take a...Ch. 2 - Implement a method, empty, that simulates the...Ch. 2 - Prob. 46ECh. 2 - Predict what you think will happen if you change...Ch. 2 - Rewrite the if-else statement so that the method...Ch. 2 - Prob. 49ECh. 2 - In this version of printTicket, we also do...Ch. 2 - Is it possible to remove the else part of the...Ch. 2 - After a ticket has been printed, could the value...Ch. 2 - So far, we have introduced you to two arithmetic...Ch. 2 - Write an assignment statement that will store the...Ch. 2 - Write an assignment statement that will divide the...Ch. 2 - Prob. 56ECh. 2 - Modify your answer to the previous exercise so...Ch. 2 - Why does the following version of refundBalance...Ch. 2 - What happens if you try to compile the...Ch. 2 - What is wrong with the following version of the...Ch. 2 - Add a new method, emptyMachine, that is designed...Ch. 2 - Rewrite the printTicket method so that it declares...Ch. 2 - Challenge exercise Suppose we wished a single...Ch. 2 - List the name and return type of this method:
Ch. 2 - Prob. 65ECh. 2 - Write out the outer wrapping of a class called...Ch. 2 - Write out definitions for the following fields:
Ch. 2 - Write out a constructor for a class called Module....Ch. 2 - Prob. 69ECh. 2 - Correct the error in this method:...Ch. 2 - Write an accessor method called getName that...Ch. 2 - Write a mutator method called setAge that takes a...Ch. 2 - Write a method called printDetails for a class...Ch. 2 - Draw a picture of the form shown in Figure 2.3,...Ch. 2 - Prob. 75ECh. 2 - Create a Student with name "djb" and id "859012"....Ch. 2 - Prob. 77ECh. 2 - Challenge exercise Modify the getLoginName method...Ch. 2 - Consider the following expressions. Try to predict...Ch. 2 - Open the Code Pad in the better-ticket-machine...Ch. 2 - Now add the following in the Code Pad:...Ch. 2 - Add the following: t1.InsertMoney500; What would...Ch. 2 - Prob. 83ECh. 2 - Prob. 84ECh. 2 - Add a field, pages, to the Book class to store the...Ch. 2 - Are the Book objects you have implemented...Ch. 2 - Add a method, printDetails, to the Book class....Ch. 2 - Add a further field, refNumber, to the Book class....Ch. 2 - Modify your printDetai 1 s method to include...Ch. 2 - Prob. 90ECh. 2 - Add a further integer field, borrowed, to the Book...Ch. 2 - Prob. 92ECh. 2 - Prob. 93ECh. 2 - Prob. 94E
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