[英]Instance Variables (object from another class)
我有一個主要的Test類,另外兩個主要的類(Book,Order類)代表一些特定的對象。 在班級Test中,我創建了5個Book對象。 現在,我想創建兩個使用Order類中的方法的Order對象。 具體來說,請使用setCustomerName(),SetCustomerAddress(),toString(),getTotlaPrice()和addBook()。在我為setCustomerName()和SetCustomerAddress()設置了吸氣劑和吸氣劑后,在測試類中沒有錯誤。 我的問題是,如何在Order類中創建5個Book實例變量,如果調用了它們(使用addBook()從Test類中),將用在Test類中創建的Book對象的成員數據(或參數)填充它們,因此我可以在同一個類的其他方法中使用它們。例如,在類Test中,如果我調用addBook(b1),則Order類中的addBook()方法應初始化或填充Book實例變量之一(我猜想這是一個對象?)是按順序創建的,使用Test類中引用的成員數據(使用b#1-5)。 這是兩個類。 我沒有把Book類放進去,因為它只是創建Book對象。 很感謝任何形式的幫助!
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
添加一個List<Book>
並將其初始化:
public class Order {
List<Book> books = new ArrayList<>();
public String addBook(Book book){
books.add(book);
return "0";
}
...
}
然后,您只需在訂單類中迭代books
以獲取總價,將其轉換為String,...
您可以在Order類中添加一個List,類似
private List<Book> books = new ArrayList<Book>();
您的方法可能類似於:
public String addBook(Book book){
books.add(book);
return "Book added";
}
這樣您就可以按訂單處理,添加,刪除和更新圖書!
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