Here is my program. All i'm trying to do is print the ArrayList at the end and it won't, what am i doing wrong I'm trying to use mls.ToString() but thats not working. Please tell me what i did wrong. PS this is homework and thanks for the help.
import java.util.ArrayList;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
ArrayList<Book> mls = new ArrayList<Book>();
String userAuthor;
String userTitle;
int userYearPub;
int userPageCount;
String answer;
int numberAnswer;
int choice;
do {
Scanner in = new Scanner(System.in);
System.out.println("Please enter the author of the book.");
userAuthor = in.next();
System.out.println();
System.out.println("Please enter the title of the book.");
userTitle = in.next();
System.out.println();
System.out.println("Please enter the year the book was published.");
userYearPub = in.nextInt();
System.out.println();
System.out.println("Please enter the number of pages of the book.");
userPageCount = in.nextInt();
System.out.println();
Book usersBook = new Book(userAuthor, userTitle, userYearPub, userPageCount);
System.out.println(usersBook.ToString());
System.out.println();
do {
System.out.println("If you want to change anything press one of the following options: ");
System.out.println('1' + " Author.");
System.out.println('2' + " Title.");
System.out.println('3' + " Year it was published.");
System.out.println('4' + " Number of pages");
System.out.println('5' + " Quit");
System.out.println();
choice = in.nextInt();
if (choice == 1) {
System.out.println("Please enter the new author:");
answer = in.next();
usersBook.setAuthor(answer);
}
if (choice == 2) {
System.out.println("Please enter the new title:");
answer = in.next();
usersBook.setTitle(answer);
}
if (choice == 3) {
System.out.println("Please enter the new year:");
numberAnswer = in.nextInt();
usersBook.setYearPub(numberAnswer);
}
if (choice == 4) {
System.out.println("Please enter the new pages count:");
numberAnswer = in.nextInt();
usersBook.setPages(numberAnswer);
}
if (choice == 5) {
break;
}
System.out.println();
System.out.println("Is this correct?");
System.out.println('1' + " yes");
System.out.println('2' + " no");
choice = in.nextInt();
if (choice == 1) break;
}while (choice == 2);
mls.add(usersBook);
System.out.println(usersBook.ToString());
System.out.println();
System.out.println("Do you want to input another book?");
System.out.println("If so press 1, if not press 2.");
choice = in.nextInt();
System.out.println(mls.ToString());
} while (choice == 1);
}
}
Here is the Book class.
public class Book {
private String author;
private String title;
private int yearPub;
private int pages;
public Book(String Author, String Title, int YearPub, int Pages)
{
this.author = Author;
this.title = Title;
this.yearPub = YearPub;
this.pages = Pages;
}
public String ToString()
{
return "The Author of this book is " + author +
"\nThe title of this book is " + title +
"\nThe year published is " + yearPub +
"\nThe number of pages is " + pages;
}
public void setAuthor(String newSring)
{
author = newSring;
}
public void setTitle(String newString)
{
title = newString;
}
public void setYearPub(int newValue)
{
yearPub = newValue;
}
public void setPages(int newValue)
{
pages = newValue;
}
}
mls
is not a Book
. It is an ArrayList<Book>
. You need to fetch the books from the list before calling ToString()
. Something like the following:
for(int i = 0; i < mls.size(); i++) {
System.out.println(mls.get(i).ToString());
}
You are triying to access the method ToString
of a List
of books "mls"
, which hasn't such method, your variable is not a book is a list of books.
You have to replace "mls.ToString()"
for "usersBook.ToString()"
in order to access your method.
PS: You should rename your method with lowercase toString
, in Java all objects implicitly inherit that method, you can/shall override it.
Problem is line with:
System.out.println(mls.ToString());
ArrayList don't have ToString() method. ArrayList have toString() method.
Solution is:
System.out.println(mls.toString());
or
System.out.println(mls);
You musn't use toString() method, it will be automatically called.
And second problem is that your toString() method in Book class should look like:
@Override
public String toString() {
return "The Author of this book is " + author +
"\nThe title of this book is " + title +
"\nThe year published is " + yearPub +
"\nThe number of pages is " + pages;
}
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