我在这里设计一个商店系统，它主要是一个媒体商店，包含视频游戏，DVD和CD等项目。我遇到的问题是我想将同一对象的不同实例（在本例中为VideoGames）存储到链表中。它似乎有效，但是当我输出List时，它只输出输入到列表中的最后一项，并重复自身以查找应该在列表中的对象数量。
我知道要查看很多代码，但任何帮助都会非常值得赞赏。
以下是addVideoGame类的代码：
import java.util.*;
import java.io.*;
public class addVideoGame extends VideoGames implements java.io.Serializable{
public static VideoGames game = new VideoGames();
public static VideoGames eGame = new VideoGames();
public static LinkedList <VideoGames> games = new LinkedList<>();
private static int vgChoice = 0;
public static int vgCount = 0;
public static int vgAmount = 0;
public static void vgMenu(){
IBIO.output("1: Add a new videogame to the list.");
IBIO.output("2: View the contents of the list.");
IBIO.output("3: Save the contents of the list to the local area.");
IBIO.output("4: Load in data from a local file.");
IBIO.output("5: Return to the main menu.");
vgChoice = IBIO.inputInt("Make your choice: ");
if(vgChoice == 1){
vgAmount = IBIO.inputInt("How many games would you like to add to the database?: ");
for(int x = 0; x < vgAmount; x = x + 1){
VideoGames vg = new VideoGames();
vg.setTitle(IBIO.inputString("Enter the title of the game: "));
vg.setPublisher(IBIO.inputString("Enter the publisher of the game: "));
vg.setDeveloper(IBIO.inputString("Enter the developer of the game: "));
vg.setAgeRating(IBIO.inputInt("Enter the age rating of the game: "));
vg.setGenre(IBIO.inputString("Enter the genre of the game: "));
vg.setQuantity(IBIO.inputInt("Enter the available quantity of the game: "));
game = vg;
games.add(vg);
IBIO.output(" ");
}
vgMenu();
} else if(vgChoice == 2){
IBIO.output("Current amount of games in the list: " + games.size());
System.out.println(Arrays.toString(games.toArray()));
vgMenu();
} else if(vgChoice == 3){
try{
FileOutputStream fileOut = new FileOutputStream("I:\\IB\\Computer Science\\TheStore\\games.txt");
ObjectOutputStream out = new ObjectOutputStream(fileOut);
out.writeObject(game);
out.close();
fileOut.close();
IBIO.output("Data has been saved to: I:\\IB\\Computer Science\\TheStore\\games.txt");
vgMenu();
} catch(IOException i){
i.printStackTrace();
}
} else if(vgChoice == 4){
eGame = null;
for(int x = 0; x < games.size(); x = x + 1){
try{
FileInputStream fileIn = new FileInputStream("I:\\IB\\Computer Science\\TheStore\\games.txt");
ObjectInputStream in = new ObjectInputStream(fileIn);
eGame = (VideoGames) in.readObject();
in.close();
fileIn.close();
} catch (IOException i){
i.printStackTrace();
return;
} catch(ClassNotFoundException c){
IBIO.output("VideoGames class not found");
c.printStackTrace();;
return;
}
IBIO.output("Object Details: " + eGame.toString());
vgMenu();
}
} else if(vgChoice == 5){
IBIO.output("Returning to main menu: ");
AccessMenus.adminMenu();
}
}
}
如果有人需要它们，这里有两个用于导航程序的接口类：
public class TheStore {
static String password; //Variable created to hold and check the value of password against the correct value.
public static boolean privilege = false; //Variable created to distinguish the difference between a normal user and a user with administrator privileges.
public static void main(String[] args) {
IBIO.output("Welcome to The Store!");
IBIO.output("Please make sure that you enter the correct password for your given privileges.");
password = IBIO.inputString("Enter password: ");
if(password.equalsIgnoreCase("admin")){ //Checks the entered value against the correct value.
privilege = true; //Sets global boolean value to true, so that admin access is granted.
IBIO.output(" ");
AccessMenus.adminMenu();//If password is correct, loads admin menu.
} else if(password.equalsIgnoreCase("user")){
privilege = false; //Keeps admin access off, so that unauthorised changes cannot be made.
IBIO.output(" ");
AccessMenus.userMenu();//If correct, loads user menu.
} else {
IBIO.output("The password is incorrect. Exiting program.");
System.exit(1); //If an incorrect password is entered, the program will close.
} //close else
}//close main
}//close class TheStore
第二个：
public class AccessMenus{
public static int choice;//Variable which will hold the value, which corresponds to an action depending on what value is entered.
public AccessMenus(){ //Null argument constructor, to set values to 0.
AccessMenus.choice = 0;
}
public AccessMenus(int c){ //Single argument constructor.
AccessMenus.choice = c;
}
public static void userMenu(){
IBIO.output("1: Sell a product.");
IBIO.output("2: Register a customer in the Loyalty programme.");
IBIO.output("3: Stock check.");
IBIO.output("4: Log out.");
IBIO.output(" ");
IBIO.output("Please make your choice: ");
choice = IBIO.inputInt();
if(choice == 1){
//Go to Sales class.
} else if(choice == 2){
//Go to CustomerRegister class.
} else if(choice == 3){
//Open the StockCheck class.
} else if(choice == 4){
IBIO.output("Logging out.");
System.exit(1);
} else {
IBIO.output("Invalid choice. Returning to menu.");
userMenu(); //If the value entered does not correspond to any action, the program will treat it as invalid and return to the menu.
}//close else
}//close userMenu
public static void adminMenu(){
IBIO.output("1: Sell a product.");
IBIO.output("2: Go to the specific object menus.");
IBIO.output("3: Stock check.");
IBIO.output("4: Order more stock.");
IBIO.output("5: Register a customer in the Loyalty programme.");
IBIO.output("6: Check Loyalty members.");
IBIO.output("7: Create databases.");
IBIO.output("8: Log out.");
IBIO.output(" ");
IBIO.output("Please make your choice: ");
choice = IBIO.inputInt();
if(choice == 1){
//Go to Sales class.
} else if(choice == 2){
int createChoice = 0;
IBIO.output("1: Video Games.");
IBIO.output("2: DVD.");
IBIO.output("3: CD.");
createChoice = IBIO.inputInt("Enter choice: ");
if(createChoice == 1){
addVideoGame.vgMenu();
} else if(createChoice == 2){
//Go to addDVD class.
} else if(createChoice == 3){
//Go to addCD class.
} else {
IBIO.output("Invalid input.");
adminMenu();
}
} else if(choice == 3){
//Go to StockCheck class.
} else if(choice == 4){
//Go to StockOrder class.
} else if(choice == 5){
//Go to CustomerRegister class.
} else if(choice == 6){
//Go to LoyaltyCheck class.
} else if(choice == 7){
//Go to DatabaseCreation class.
} else if(choice == 8){
IBIO.output("Logging out.");
System.exit(1);
} else {
IBIO.output("Invalid input. Returning to menu.");
adminMenu();
} //end else
}//close AdminMenu
}//close AccessMenus
此外，这里是VideoGames对象类，包含访问器和mutator方法以及主要字段：
public class VideoGames implements java.io.Serializable {
//Instance variables
public static String title;
public static int ageRating;
public static String genre;
public static String publisher;
public static String developer;
public static int quantity;
public VideoGames(){ //null argument constructor
VideoGames.title = null;
VideoGames.ageRating = 0;
VideoGames.genre = null;
VideoGames.publisher = null;
VideoGames.developer = null;
VideoGames.quantity = 0;
}//end VideoGames null argument constructor
public VideoGames(String t, int aG, String g, String p, String d, int q){ //6-argument constructor
VideoGames.title = t;
VideoGames.ageRating = aG;
VideoGames.genre = g;
VideoGames.publisher = p;
VideoGames.developer = d;
VideoGames.quantity = q;
}//end VideoGames 6-arguement constructor
public VideoGames(VideoGames game){
game = new VideoGames();
}
@Override
public String toString(){
return "\nTitle: " + title + " " + "\nPublisher: " + publisher + " " + "\nDeveloper: " + developer + " " + "\nAge Rating: " + ageRating + " " + "\nGenre: " + genre + " " + "\nQuantity: " + quantity + "\n ";
}
//Accessor and Mutator methods
public static String getTitle(){
return title;
}
public static void setTitle(String t){
title = t;
}
public static int getAgeRating(){
return ageRating;
}
public static void setAgeRating(int ag){
ageRating = ag;
}
public static String getGenre(){
return genre;
}
public static void setGenre(String g){
genre = g;
}
public static String getPublisher(){
return publisher;
}
public static void setPublisher(String p){
publisher = p;
}
public static void setDeveloper(String d){
developer = d;
}
public static String getDeveloper(){
return developer;
}
public static void setQuantity(int q){
quantity = q;
}
public static int getQuantity(){
return quantity;
}//end method setDeveloper
}//end class VideoGames
再次，非常感谢任何帮助。
答案 0 :(得分：1)
我有太多代码可以正常通过，但听起来像（并且快速扫描似乎确认）您只创建一个VideoGames对象。每当您更改该对象中的任何字段时，它都会更改该单个对象中的字段。
然后将同一个VideoGames对象多次添加到列表中，但这些都是对同一对象的单独引用。
而VideoGames应该被称为VideoGame，并且包含一个游戏的数据，然后您应该创建new VideoGame()并在每次向列表中添加一个游戏时进行设置。
请记住，列表只包含对象的引用，而不包含对象本身。
每个VideoGames对象就像一条街上的房子。目前你建造了一所房子，并在那栋房子的门上不断涂上不同的颜色，而不是建造多个房屋，并在每个房子的门上涂上不同的颜色。
当您添加相同的房子时，您的列表只是一个地址列表，只有4次列表重复相同的地址。
所以你在做：
在地块1中建造房屋
现在你走到列表中，你看到三个条目 - 但是当你去看门颜色时，他们都说红色。
答案 1 :(得分：0)
您在VideoGames -class中使用静态成员。 这个值会影响所有对象，例如
public class X {
public static int y;X() { }
public
}
X x1 = new X();
x1.y = 1;
X x2 = new X();
x2.y = 2;
System.out.println("x1.y" + x1.y); // 2
System.out.println("x2.y" + x2.y); // 2
答案 2 :(得分：0)
VideoGames类的字段都是静态的。静态字段属于Class，JVM的方法区域只有一个内存空间。当你执行for循环：
VideoGames vg = new VideoGames();
您创建了一个VideoGames实例，但是当您执行set method时：
vg.setTitle(IBIO.inputString("Enter the title of the game: "));
vg.setPublisher(IBIO.inputString("Enter the publisher of the game: "));
vg.setDeveloper(IBIO.inputString("Enter the developer of the game: "));
vg.setAgeRating(IBIO.inputInt("Enter the age rating of the game: "));
vg.setGenre(IBIO.inputString("Enter the genre of the game: "));
vg.setQuantity(IBIO.inputInt("Enter the available quantity of the game: "));
您收到的数据将设置为方法区域中的静态字段。您之前设置的值将由您设置的值覆盖。当您打印列表的值时。您将从方法区域中的静态字段中获取值。
所以， 但是当我输出List时，它只输出输入到列表中的最后一项，并重复自身以查找应该在列表中的对象数量。
希望能帮到你。 抱歉我的英语不好。