[英]Instance Variables (object from another class)
我有一个主要的Test类,另外两个主要的类(Book,Order类)代表一些特定的对象。 在班级Test中,我创建了5个Book对象。 现在,我想创建两个使用Order类中的方法的Order对象。 具体来说,请使用setCustomerName(),SetCustomerAddress(),toString(),getTotlaPrice()和addBook()。在我为setCustomerName()和SetCustomerAddress()设置了吸气剂和吸气剂后,在测试类中没有错误。 我的问题是,如何在Order类中创建5个Book实例变量,如果调用了它们(使用addBook()从Test类中),将用在Test类中创建的Book对象的成员数据(或参数)填充它们,因此我可以在同一个类的其他方法中使用它们。例如,在类Test中,如果我调用addBook(b1),则Order类中的addBook()方法应初始化或填充Book实例变量之一(我猜想这是一个对象?)是按顺序创建的,使用Test类中引用的成员数据(使用b#1-5)。 这是两个类。 我没有把Book类放进去,因为它只是创建Book对象。 很感谢任何形式的帮助!
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
public class Test
{
public static void main(String args[]) throws ParseException
{
SimpleDateFormat fmt = new SimpleDateFormat(Book.DATE_FORMAT);
// Creating Book-objects...
Book b1 = new Book(1, "Homo Faber", "Max Frisch", fmt.parse("01.01.1957"), -10);
Book b2 = new Book(2, "Harry Potter", "J.K. Rowling", fmt.parse("25.7.2000"), 45);
Book b3 = new Book(3, "Krieg und Frieden", "Leo Tolstoi", fmt.parse("24.01.1867"), 29);
Book b4 = new Book(4, "Freedom", "Jonathan Franzen", fmt.parse("08.06.2010"), 39);
Book b5 = new Book(5, "Goedel, Escher, Bach", "Douglas Hofstadter", fmt.parse("05.11.1979"), 42);
// Creating two orders containing theses books...
Order order = new Order();
order.setCustomerName("Sophie Muster");
order.setCustomerAddress("Mittelstrasse 10, 3011 Bern");
order.addBook(b1);//Here i want to fill one of the Book instance variables (i guess this is an object to?) created
order.addBook(b2);//in the Order class with the member data of the
order.addBook(b3);//Book objects referenced (with b#1-5) which i have created above.
order.addBook(b4);
order.addBook(b4);
order.addBook(b5);
System.out.println(order);
System.out.print("\n");
Order order2 = new Order();
order2.setCustomerName("Woody Allen");
order2.setCustomerAddress("5th Avenue 7, 10001 New York");
order2.addBook(b5);
System.out.println(order2);
}
}
。
public class Order {
private static int idCounter;
private int id;
private String customerName;
private String customerAddress;
// The Constructor
public Order(int tmpId, String tmpCustomerName,String tmpCustomerAddress){
if (idCounter == 1);{
id = 1;}
if (idCounter == 2){
id = 2;}
if (idCounter == 3);{
id = 3;}
if (idCounter == 4){
id = 4;}
if (idCounter == 5){
id = 5;}
customerName = tmpCustomerName;
customerAddress = tmpCustomerAddress;
}
public Order() {
id = 0;
customerName = "-";
customerAddress = "-";
}
// The methods
public String toString()
{
return id + ", " + customerName + ", " + customerAddress;
}
public String addBook(){
//HERE with this method i want to add some of the Book objects i have made in Test class
// ?? Book b1 = Test.b1(); ??
return "0";
}
public int getTotalPrice(){
return 0;
}
public String getCustomerName()
{
return customerName;
}
public String setCustomerName(String tmpCustomerName){
customerName = tmpCustomerName;
return customerName;
}
public String getCustomerAddress()
{
return customerAddress;
}
public String setCustomerAddress(String tmpCustomerAddress){
customerAddress = tmpCustomerAddress;
return customerAddress;
}
}
您只需在Order
添加一个List<Book>
并将其初始化:
public class Order {
List<Book> books = new ArrayList<>();
public String addBook(Book book){
books.add(book);
return "0";
}
...
}
然后,您只需在订单类中迭代books
以获取总价,将其转换为String,...
您可以在Order类中添加一个List,类似
private List<Book> books = new ArrayList<Book>();
您的方法可能类似于:
public String addBook(Book book){
books.add(book);
return "Book added";
}
这样您就可以按订单处理,添加,删除和更新图书!
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