这是如果我的第一个问题在stackoverflow。我通常可以自己找到答案,但我遇到了这个问题。我有两个对象,“书”和“期刊”。这些是“发布”类的子类。现在,我正在尝试将3个“Book”实例和3个“Periodical”实例添加到ArrayList。我无法弄清楚如何做到这一点。 。将对象添加到ArrayList
有了这个当前的代码,我得到一个错误“找到加(图书,图书,图书,期刊,期刊,期刊)没有合适的方法
下面是当前的代码:
import java.util.ArrayList;
import java.util.Date;
public class DriverProgram {
public static void main(String[] args) {
// Instantiate 3 instances of each object.
Book book1 = new Book(1234, 1, "James", 100, "Hello", "Berkwood Inc.", new java.util.Date(), "History");
Book book2 = new Book(2345, 2, "Ralph", 200, "Goodbye", "Shackles Co.", new java.util.Date(), "English");
Book book3 = new Book(3456, 3, "Julia", 300, "Hello Again", "Trustin Inc.", new java.util.Date(), "History");
Periodical periodical1 = new Periodical("Daily", "Dylan", "History 101", "History Inc.", new java.util.Date(), "History");
Periodical periodical2 = new Periodical("Weekly", "Jannette", "Mathematics 101", "Mathematics Inc.", new java.util.Date(), "Mathematics");
Periodical periodical3 = new Periodical("Monthly", "Patricia", "Science 101", "Science Inc.", new java.util.Date(), "Science");
// Create an array list of the Publication class type, and add the objects to it.
ArrayList <Publication> publications = new ArrayList<Publication>();
publications.add(book1, book2, book3, periodical1, periodical2, periodical3);
// Pass the array list to a method to loop through it and display the toString methods.
displayObjects(publications);
} // End of main
static void displayObjects (ArrayList<Publication> publications) {
// Loop through array list and display the objects using the toString methods.
for (Publication p : publications) {
System.out.print(p.toString());
} // End of for each loop
} // End of displayObjects
} // End of DriverProgram class
我也试着改变:
publications.add(book1, book2, book3, periodical1, periodical2, periodical3);
要这样:
publications.add(book1);
publications.add(book2);
publications.add(book3);
publications.add(periodical1);
publications.add(periodical2);
publications.add(periodical3);
它摆脱了我的程序编译器错误,但它只是打印“periodical3”对象,6次。我不确定我做错了什么。有什么建议么?先谢谢你! :)
编辑:
这里是我的书类:
public class Book extends Publication{
private static int isbn = 0;
private static int libraryOfCongressNbr = 0;
private static String author = "";
private static int nbrOfPages = 0;
// Constructor for Book class with parameters for each attribute.
public Book(int newISBN, int newLibraryOfCongressNbr, String newAuthor, int newNbrOfPages, String newTitle, String newPublisher, java.util.Date newPublicationDate, String newSubject) {
super(newTitle, newPublisher, newPublicationDate, newSubject);
isbn = newISBN;
libraryOfCongressNbr = newLibraryOfCongressNbr;
author = newAuthor;
nbrOfPages = newNbrOfPages;
}
/////////////////////////////////////////////////////// Getters ///////////////////////////////////////////////////////
int getISBN() {
return isbn;
}
int getLibraryOfCongressNbr() {
return libraryOfCongressNbr;
}
String getAuthor() {
return author;
}
int getNbrOfPages() {
return nbrOfPages;
}
/////////////////////////////////////////////////////// Setters ///////////////////////////////////////////////////////
void setISBN(int newISBN) {
isbn = newISBN;
}
void setLibraryOfCongressNbr(int newLibraryOfCongressNbr) {
libraryOfCongressNbr = newLibraryOfCongressNbr;
}
void setAuthor(String newAuthor) {
author = newAuthor;
}
void setNbrOfPages(int newNbrOfPages) {
nbrOfPages = newNbrOfPages;
}
//toString method for Book class
public String toString() {
StringBuilder result = new StringBuilder();
result.append("\nISBN: " + isbn + "\n");
result.append("\nPublisher: " + libraryOfCongressNbr + "\n");
result.append("\nAuthor: " + author + "\n");
result.append("\nNumber of Pages: " + nbrOfPages + "\n");
result.append("--------------------------------------------------------- ");
return super.toString() + result.toString();
} // End of toString
} // End of Book class
我的期刊类是相同的,但这里是我的出版类:
import java.util.Date;
public abstract class Publication {
// Data fields.
private static String title = "";
private static String publisher = "";
private static java.util.Date publicationDate;
private static String subject = "";
// Constructor for Publication class with parameters for each attribute.
public Publication(String newTitle, String newPublisher, java.util.Date newPublicationDate, String newSubject){
title = newTitle;
publisher = newPublisher;
publicationDate = newPublicationDate;
subject = newSubject;
}
/////////////////////////////////////////////////////// Getters ///////////////////////////////////////////////////////
String getTitle() {
return title;
}
String getPublisher() {
return publisher;
}
java.util.Date getPublicationDate() {
return publicationDate;
}
String getSubject() {
return subject;
}
/////////////////////////////////////////////////////// Setters ///////////////////////////////////////////////////////
void setTitle(String newTitle) {
title = newTitle;
}
void setPublisher(String newPublisher) {
publisher = newPublisher;
}
void setPublicationDate(java.util.Date newPublicationDate) {
publicationDate = newPublicationDate;
}
void setSubject(String newSubject) {
subject = newSubject;
}
//toString method for Publication class
public String toString() {
StringBuilder result = new StringBuilder();
result.append("\nTitle: " + title + "\n");
result.append("\nPublisher: " + publisher + "\n");
result.append("\nPublication Date: " + publicationDate + "\n");
result.append("\nSubject: " + subject + "\n");
return result.toString();
} // End of toString
} // End of Publication class
让我知道,如果你需要别的东西!
编辑x2:对不起,我意识到我的帖子越来越长。
因此,我已经从我的类变量或“数据字段”中删除了我在代码中调用它们的所有“静态”关键字。然后,我将我的代码更改回此代码:
ArrayList <Publication> publications = new ArrayList<Publication>();
publications.add(book1);
publications.add(book2);
publications.add(book3);
publications.add(periodical1);
publications.add(periodical2);
publications.add(periodical3);
它的工作原理!它执行它应该!我只有一个问题,虽然,这似乎代码,因为没有工作:
publications.add(book1, book2, book3, periodical1, periodical2, periodical3);
有一个较短的方式来添加所有的对象与出的ArrayList做逐一?
从'Publication'类(及其子类)内的所有字段中移除'static'。 –
这是相当多的猜测:)。可能是真的。你可以发布你的“出版”和“书”类吗? – Tunaki
最有可能重复[为什么我的ArrayList包含添加到列表中的最后一个项目的N个副本?](http://stackoverflow.com/q/19843506/1393766) – Pshemo