Objects First with Java: A Practical Introduction Using BlueJ (6th Edition)
6th Edition
ISBN: 9780134477367
Author: David J. Barnes, Michael Kolling
Publisher: PEARSON
expand_more
expand_more
format_list_bulleted
Concept explainers
Videos
Textbook Question
Chapter 4, Problem 34E
In the findFirst method, the loop's condition repeatedly asks the flies collection how many files it is storing. Does the value returned by size vary from one check to the next? If you think the answer is no, then rewrite the method so that the number of files is determined only once and stored in a local variable prior to execution of the loop. Then use the local variable in the loop's condition rather than the call to size. Check that this version gives the same results. If you have problems completing this exercise, try using the debugger to see where things are going wrong.
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
In Java
I did an insert method for my program, but I want to make sure its correct, please check it and fix if theres any errors
the code
public void insert(E key) throws DuplicateItemException { BSTNode<E> child = new BSTNode(key); if ( root == null ) { root = child; } else { BSTNode<E> parent = insertionPoint(key); } try { BSTNode<E> parent = insertionPoint(key); if (key.compareTo(parent.getKey()) < 0){ parent.setLeftChild(child); } else if (key.compareTo(parent.getKey()) > 0) { parent.setRightChild(child); } } catch (DuplicateItemException ex) { throw ex; } }
We know that the first file name is stored at index zero in the ArrayList, and the list stores the file names as strings, so could we write the body of listAllFiles along the following lines? System.out.println(files.get(0)); System.out.println(files.get(1)); System.out.println(files.get(2)); etc. How many println statements would be required to complete the method?
Why not create a single Collection data type that includes methods to add items, remove most recently inserted items, remove least recently inserted items, remove random items, iterate, return the collection's item count, and any other actions we might need? Then we could build each one in a single class that many clients could use.
ans in 10 min
Chapter 4 Solutions
Objects First with Java: A Practical Introduction Using BlueJ (6th Edition)
Ch. 4 - Prob. 1ECh. 4 - What happens if you create a new MusicOrganizer...Ch. 4 - Prob. 3ECh. 4 - Prob. 4ECh. 4 - Write a declaration of a local variable called...Ch. 4 - Prob. 6ECh. 4 - Write assignments to the library, cs101. and track...Ch. 4 - If a collection stores 10 objects, what value...Ch. 4 - Write a method call using get to return the fifth...Ch. 4 - Prob. 10E
Ch. 4 - Write a method call to add the object held in the...Ch. 4 - Write a method call to remove the third object...Ch. 4 - Suppose that an object is stored at index 6 in a...Ch. 4 - Add a method called checklndex to the...Ch. 4 - Write an alternative version of checkIndex called...Ch. 4 - Rewrite both the 1istFi1e and removeFi1e methods...Ch. 4 - Prob. 17ECh. 4 - Prob. 18ECh. 4 - We know that the first file name is stored at...Ch. 4 - Prob. 20ECh. 4 - Create a MusicOrganizer and store a few file names...Ch. 4 - Create an ArrayList<String> in the Code Pad by...Ch. 4 - If you wish, you could use the debugger to help...Ch. 4 - Challenge exercise The for-each loop does not use...Ch. 4 - Prob. 25ECh. 4 - Prob. 26ECh. 4 - Prob. 27ECh. 4 - Write out the header of a for-each loop to process...Ch. 4 - Suppose we express the first version of the key...Ch. 4 - Write a while loop (for example, in a method...Ch. 4 - Write a while loop to add up the values 1 to 10...Ch. 4 - Write a method called sum with a while loop that...Ch. 4 - Challenge exercise Write a method isPrime (int n)...Ch. 4 - In the findFirst method, the loop's condition...Ch. 4 - Prob. 35ECh. 4 - Have the MusicOrganizer increment the play count...Ch. 4 - Prob. 37ECh. 4 - Prob. 38ECh. 4 - Prob. 39ECh. 4 - Prob. 40ECh. 4 - Complete the numberOfMembers method to return the...Ch. 4 - Prob. 42ECh. 4 - Prob. 43ECh. 4 - Prob. 44ECh. 4 - Challenge exercise Write a method to play every...Ch. 4 - Prob. 46ECh. 4 - Prob. 47ECh. 4 - Add a close method to the Auction class. This...Ch. 4 - Add a getUnsold method to the Auction class with...Ch. 4 - Suppose the Auction class includes a method that...Ch. 4 - Rewrite getLot so that it does not rely on a lot...Ch. 4 - Prob. 52ECh. 4 - Prob. 53ECh. 4 - Prob. 54ECh. 4 - Prob. 55ECh. 4 - Open the products project and complete the...Ch. 4 - Implement the findProduct method. This should look...Ch. 4 - Implement the numberInStock method. This should...Ch. 4 - Prob. 59ECh. 4 - Challenge exercise Implement a method in...Ch. 4 - Java provides another type of loop: the do-while...Ch. 4 - Prob. 85ECh. 4 - Prob. 86ECh. 4 - Find out about Java's switch-case statement. What...
Additional Engineering Textbook Solutions
Find more solutions based on key concepts
The ________ object is assumed to exist and it is not necessary to include it as an object when referring to it...
Web Development and Design Foundations with HTML5 (8th Edition)
Corporate Sales A corporation has six divisions, each responsible for sales to different geographic locations. ...
Starting Out with C++: Early Objects (9th Edition)
What is the value of the program counter in the Vole immediately after executing the instruction 0xB0CD?
Computer Science: An Overview (12th Edition)
What is the highest decimal number that can be represented by each of the following numbers of binary digits (b...
Digital Fundamentals (11th Edition)
Consider the following C program void fun (void) { int a, b, c; / defiinition.1 / . . . while (. . .) int b, c,...
Concepts Of Programming Languages
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, computer-science and related others by exploring similar questions and additional content below.Similar questions
- Thank you very much for explaining the absyract concept, it was very helpful and easier to understanc after you explained it. Today we are asked to modify the GridWriter class by adding additional collection style functionality, to throw an exception in case of an error. The GridWriter class should get two new methods: public int size() should return the number of GridItems stored in the GridWriter public GridItem get(int index) should return the stored GridItems by index. Consider the following code. The first line creates a GridWriter object. Then two items are added to the GridWriter. The index of the items will be 0, and 1. Notice how the for loop uses the size and get methods to print out the areas of the two items GridWriter gw = new GridWriter(40, 50); gw.add(new MyCircle(10, 10, 9)); gw.add(new MyRectangle(40, 0, 10, 10)); for (int i = 0; i < gw.size(); i++) { System.out.println(gw.get(i).getArea()); } Once you have these two methods working you…arrow_forwardAnswer the given question with a proper explanation and step-by-step solution. Write a method that takes in an array of Point2D objects, and then analyzes the dataset to find points that are close together. Be sure to review the Point2D API. In your method, if the distance between any pair of points is less than 10, display the distance and the (x,y)s of each point. For example, "The distance between (3,5) and (8,9) is 6.40312." The complete API for the Point2D ADT may be viewed at http://www.ime.usp.br/~pf/sedgewick-wayne/algs4/documentation/Point2D.htmlLinks to an external site.. Do not compare a point to itself! Try to write your program directly from the API - do not review the ADT's source code. (Don't worry too much about your answer compiling - focus on using an API from its documentation.) Your answer should include only the method you wrote, do not write a complete program.arrow_forwardIn python. Please do not copy elsewhere as it is all incorrect, and include docstring so that I can understand the information so I can apply the methods to future problems. Thanks. import the **json** module.Write a class named SatData that reads a [JSON file containing data on 2010 SAT results for New York City](https://data.cityofnewyork.us/api/views/zt9s-n5aj/rows.json?accessType=DOWNLOAD) and writes the data to a text file in CSV format. That same JSON file will be provided as a local file in Gradescope named **sat.json**. Your code does not need to access the internet.CSV is a very simple format - just commas separating columns and newlines separating rows (see note below about commas that are part of field names). You'll see an example of CSV format below. There is a csv module for Python, but you will not use it for this project.Your class should have:* an init method that reads the file and stores it in whatever data member(s) you prefer. Any data members of the SatData class…arrow_forward
- You are to implement removeHead, and removeTail and you also have to create the following functions (for visual purposes of the detail explanation, header and trailer sentinels are described as h and t respectively): IMPORTANT NOTE: For all the methods that has the pos parameter i.e. addAt, removeAt, move, make sure to access that specified position from whichever is nearer - the head or the tail - similar to what we have done in the get method. Example DoublyLinkedList: h <-> 10 <-> 30 <-> 40 <-> 50 <-> t int add(int num) This will add the element num into the last element of the linked list and return the position of the newly-added element. In the above example, having add(60) will return 5 as it is the fifth position in the list. int remove(int num) This will remove the first instance of the element and return the position of the removed element. In the above example, having remove(40) will return 3 as 40 was the third element in the linked list…arrow_forwardYou are given a text file (Words.txt) containing 50 words that will be hard to make out because they have been littered with punctuation. Your task is to: • Create a new file called Words2.txt, from Words.txt, which contains all the strings from the previous file, with their position, but with all the punctuation removed. (You must create some sort of method that can loop through the words to do this, you are not allowed to use Regex Patterns) Hint: This might come in handy String punctuation = "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~"; • You must find the first longest word that appears in the text file with their position retained as well as indicating the number of characters therein, the formatting for this can be seen in Table 1.arrow_forwardPlease written by computer source Has to return string//ToDo 4 add a getter method - getYear - to return just the Year value of the date // see other filepublic String getYear() { //To Do }arrow_forward
- There are multiple test files for this project. My program must handle not only the expected file but also files with missing records, missing data, bad data, no records, and no file. Please help me with my Python code. def read_data(filename): try: with open(filename, "r") as file: return file.read() except FileNotFoundError: print("Error: Please provide an input file ") return "" except Exception as ex: print("Error:",ex) return "" def extract_data(tags, strings): data = [] start_tag = f"<{tags}>" end_tag = f"</{tags}>" while start_tag in strings: try: start_index = strings.find(start_tag) + len(start_tag) end_index = strings.find(end_tag) if end_index == -1: break value = strings[start_index:end_index] if value: data.append(value) strings = strings[end_index + len(end_tag):] except Exception as…arrow_forwardshows the UserManagement class that contains the main methodof our program. It creates and adds several users, allows the user to search forthem interactively, and then prints all of the users in the collection.arrow_forwardImprove the method printList to print out the details of all publications ordered on the category of the publications, and then on the title within each category. Note: currently there are only 2 categories, i.e. Book and Journal, but the project may be expended by adding other categories, e.g. Newspaper etc. Here are my four classes. public class Database {private ArrayList<Publication> publicationList; // An array list collection of publications /*** Create a new database*/public Database() {publicationList = new ArrayList<Publication>();} /*** Add a publication** @param publication The publication to be added*/public void addPublication(Publication publication) {if (publicationList.contains(publication)) {System.out.println("This publication has already been added to the list: " + publication);} else {publicationList.add(publication);}} /*** Get the total number of publications** @return The total number of publications*/public int getTotal() {return…arrow_forward
- In the Utils class provided to you in this exercise, please fill in the details for a method called swapArray(). You can either upload a file or use the Edit tab to submit your work. The VPL tester will pass an arbitrary array of type integer to your method, along with the value of the locations in the array of two values that need to be swapped (exchanged). For instance, in the illustration below, the method swapArray is told to swap the values in positions 0 and 2 of an array made up of {10, 20, 30, 40, 50}. The three input parameters to the method are the array, as well as the two array indices (i and j) that control which elements to swap. Your task is to write the contents of the method that can execute this swap.arrow_forwardC++ Given the commands below, what do they do? for (position = 1 through aList.getLength()/2) { a = aList.getEntry(aList.getLength()-position+1) aList.setEntry(aList.getEntry(aList.getLength()-position+1)) aList.setEntry(a,position) } A. randomize the entries B. sort the entries C. reverse the order of the entries D. count how many entries there arearrow_forwardThe code given below represents a saveTransaction() method which is used to save data to a database from the Java program. Given the classes in the image as well as an image of the screen which will call the function, modify the given code so that it loops through the items again, this time as it loops through you are to insert the data into the salesdetails table, note that the SalesNumber from the AUTO-INCREMENT field from above is to be inserted here with each record being placed into the salesdetails table. Finally, as you loop through the items the product table must be update because as products are sold the onhand field in the products table must be updated. When multiple tables are to be updated with related data, you should wrap it into a DMBS transaction. The schema for the database is also depicted. public class PosDAO { private Connection connection; public PosDAO(Connection connection) { this.connection = connection; } public void…arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Microsoft Visual C#Computer ScienceISBN:9781337102100Author:Joyce, Farrell.Publisher:Cengage Learning,
Microsoft Visual C#
Computer Science
ISBN:9781337102100
Author:Joyce, Farrell.
Publisher:Cengage Learning,
Constants, Variables, Data types, Keywords in C Programming Language Tutorial; Author: LearningLad;https://www.youtube.com/watch?v=d7tdL-ZEWdE;License: Standard YouTube License, CC-BY