我制作了其中通用arrayList初始化为＆的Product类 当我从主类中设置Laptop arraylist和Desktop ArrayList时出现问题，如果我添加了5台笔记本电脑，然后又添加了5台台式机，那么5台台式机在5台笔记本电脑上的位置将在第5个索引之后不再使用。在笔记本电脑数据完成后开始。当我通过该类中的getter方法打印“笔记本电脑ArrayList”和“桌面Arraylist”时，只会出现“桌面ArrayList”数据。
对不起，我的英语。如果您听不懂
import java.util.ArrayList;
public class Main {public static void main(String[] args) {
Products P1 = P1=new Products();
Laptop L1= new Laptop(1,"Dell","XPS","i7|2.8GHZ|8th Gen",95000);
Laptop L2= new Laptop(2,"HP","Probook","i5|2.4GHZ|7th Gen",85000);
Laptop L3= new Laptop(3,"Lenovo","Ideapad","i7|2.6 GHZ|7th Gen",80000);
Laptop L4= new Laptop(4,"Sony","Vaio","i5|2.2 GHZ|7th Gen",90000);
Laptop L5= new Laptop(5,"Asus","Zenbook","i3|2.6 GHZ|6th Gen",75000);
Desktop D1 = new Desktop(7,"i5-2.8GHZ","6th Gen","1 TB",16,40000);
Desktop D2 = new Desktop(8,"i7-2.6GHZ","7th Gen","2 TB",32,85000);
Desktop D3 = new Desktop(9,"i5-8500","8th Gen","3 TB",16,90000);
Desktop D4 = new Desktop(10,"i7-7800","7th Gen","1 TB",16,75000);
Desktop D5 = new Desktop(11,"i3-8350","8th Gen","1 TB",32,65000);
ArrayList<Laptop> laptop = new ArrayList<Laptop>();
laptop.add(L1);
laptop.add(L2);
laptop.add(L3);
laptop.add(L4);
laptop.add(L5);
laptop.add(L6);
ArrayList<Desktop> desktop = new ArrayList<Desktop>();
desktop.add(D1);
desktop.add(D2);
desktop.add(D3);
desktop.add(D4);
desktop.add(D5);
for(int i = 0; i<laptop.size(); i++){
P1.setProduct(laptop);
}
for( int j=0;j<desktop.size();j++){
P1.setProduct(desktop);
}
P1.specifyCategory();
}
}
和
import java.util.ArrayList;
import java.util.Scanner;
public class Products<T> extends Category{
private ArrayList<T> product;
public Products() {
}
Products(ArrayList<T> product) {
this.product.addAll(product);
}
void specifyCategory(){
super.categories();
Scanner input4 = new Scanner(System.in);
System.out.println("\t\t\t\t\t\t\tChoose\n\t\t\t\t\t\t\t 1 for Laptop\n\t\t\t\t\t\t\t 2 for Desktop\n\t\t\t\t\t\t\t 3 for Accessories\n\t\t\t\t\t\t\t 4 for Services\n\t\t\t\t\t\t\t 5 for Contact Us");
int no=input4.nextInt();
if(no==1){
System.out.println("\t\t\t\t\t\t\t*\t\t\t\t\t\t\t\t\t1.Laptop\t\t\t\t\t\t\t\t\t\t\t*");
System.out.println(getLaptop());
}
else if(no==2){
System.out.println("\t\t\t\t\t\t\t*\t\t\t\t\t\t\t\t\t2.Desktops\t\t\t\t\t\t\t\t\t\t\t*");
//
System.out.println(getDesktop());
}
else if(no==3){
System.out.println("\t\t\t\t\t\t\t*\t\t\t\t\t\t\t\t\t3.Accessories\t\t\t\t\t\t\t\t\t\t*");
// addAccessoriesInventory();
}
else if(no==4){
System.out.println("\t\t\t\t\t\t\t*\t\t\t\t\t\t\t\t\t5.Services \t\t\t\t\t\t\t\t\t\t\t*");
}
else if(no==5){
System.out.println("\t\t\t\t\t\t\t*\t\t\t\t\t\t\t\t\t6.Contact Us\t\t\t\t\t\t\t\t\t\t*");
}
else{
System.out.println("You have entered incorrect option");
specifyCategory();
}
}
public ArrayList<Laptop> getLaptop(){
return (ArrayList<Laptop>) this.product;
}
public ArrayList<Desktop> getDesktop(){
return (ArrayList<Desktop>) this.product;
}
public void setProduct(ArrayList<T> product) {
this.product = product;
}
}
答案 0 :(得分：0)
我已在下面复制的部分代码中添加了一些注释，希望它有助于显示发生的情况。您的逻辑基本上是
在Main中，您有
// Create a laptop ArrayList and add 5 Laptops
ArrayList<Laptop> laptop = new ArrayList<Laptop>();
laptop.add(L1);
laptop.add(L2);
laptop.add(L3);
laptop.add(L4);
laptop.add(L5);
laptop.add(L6);
// Create a desktop ArrayList and add 5 Desktops
ArrayList<Desktop> desktop = new ArrayList<Desktop>();
desktop.add(D1);
desktop.add(D2);
desktop.add(D3);
desktop.add(D4);
desktop.add(D5);
// Loop 5 times
for(int i = 0; i<laptop.size(); i++){
// pass the laptop arraylist to P1.setProduct method
// The setProduct method replaces the current product list with whatever you pass in
P1.setProduct(laptop);
}
// loop 5 times
for( int j=0;j<desktop.size();j++){
// pass the desktop arraylist to P1.setProduct method
// The setProduct method replaces the current product list with whatever you pass in
P1.setProduct(desktop);
}
在您拥有的产品中
public void setProduct(ArrayList<T> product) {
this.product = product;
}
答案 1 :(得分：0)
@Zash这只是如何存储所有产品的一个示例。
要将所有台式机和笔记本电脑存储在一个产品列表中，您需要使台式机和笔记本电脑类共享一个子类或接口。通常最好是首选接口而不是子类，因此这是一个示例。
public interface Product {
String getDescription();
}
台式机和笔记本电脑类
public class Desktop implements Product {
private String description;
public Desktop(String description) {
this.description = description;
}
public String getDescription() {
return description;
}
}
public class Laptop implements Product {
private String description;
public Laptop(String description) {
this.description = description;
}
public String getDescription() {
return description;
}
}
Products类用于存储所有台式机和笔记本电脑，并且还允许检索其中的列表
import java.util.ArrayList;
import java.util.List;
public class Products {
List<Product> products = new ArrayList<>();
public void addProduct(Product product) {
products.add(product);
}
public List<Product> getProductsOfType(Class productType) {
List<Product> productsOfType = new ArrayList<Product>();
for (Product product : products) {
if (productType.isInstance(product)) {
productsOfType.add(product);
}
}
return productsOfType;
}
}
利用上述内容的主类
public class Main {
public static void main(String[] args) {
Products products = new Products();
products.addProduct(new Laptop("Dell XPS i7|2.8GHZ|8th Gen"));
products.addProduct(new Laptop("HP Probook i5|2.4GHZ|7th Gen"));
products.addProduct(new Desktop("i5-2.8GHZ 6th Gen 1 TB"));
products.addProduct(new Desktop("i7-2.6GHZ 7th Gen 2 TB"));
System.out.println("Desktops : ");
for (Product desktop : products.getProductsOfType(Desktop.class)) {
System.out.println(desktop.getDescription());
}
System.out.println("Laptops : ");
for (Product laptop : products.getProductsOfType(Laptop.class)) {
System.out.println(laptop.getDescription());
}
}
}