如何解决Java中使用数组列表的继承
我在Java中使用简单继承，但无法从父类获取值。我遵循Java中的所有标准，但是返回的是空的。我知道要访问父类，我们必须使用super关键字。但是我的程序中得到了price_ofProducts的空数组。我在哪里弄错了？需要一个方向。这是我的代码：
package project;
import java.util.ArrayList;
public class Main{
public static void main(String args[])
{
Product p = new Product();
p.name_ofProducts.add("laptop");
p.price_ofProducts.add(5000);
p.Quantity_ofProducts.add(3);
p.name_ofProductCompany.add("dell");
p.Product_idNumber.add(287);
p.name_ofProducts.add("Moblie");
p.price_ofProducts.add(3000);
p.Quantity_ofProducts.add(3);
p.name_ofProductCompany.add("Nokia");
p.Product_idNumber.add(3567);
p.name_ofProducts.add("I pad");
p.price_ofProducts.add(9000);
p.Quantity_ofProducts.add(5);
p.name_ofProductCompany.add("hp");
p.Product_idNumber.add(7845);
p.name_ofProducts.add("ispot");
p.price_ofProducts.add(600);
p.Quantity_ofProducts.add(2);
p.name_ofProductCompany.add("Nokia");
p.Product_idNumber.add(233);
p.name_ofProducts.add("Oven");
p.price_ofProducts.add(10000);
p.Quantity_ofProducts.add(5);
p.name_ofProductCompany.add("Orient");
p.Product_idNumber.add(766);
p.name_ofProducts.add("AC");
p.price_ofProducts.add(15000);
p.Quantity_ofProducts.add(5);
p.name_ofProductCompany.add("Haier");
p.Product_idNumber.add(577);
p.dispalyProduct();
// System.out.println("Price of Products Array: " + p.price_ofProducts.get(1));
Transaction tr1 = new Transaction();
tr1.Product_Number();
//p.displayProduct();
}
}
我的产品：
/*
* To change this license header,choose License Headers in Project Properties.
* To change this template file,choose Tools | Templates
* and open the template in the editor.
*/
package project;
import java.util.*;
/**
*
* @author zfhas
*/
public class Product {
protected int Quantity;
protected int price;
protected String name;
protected int id;
protected String company;
protected ArrayList<String> name_ofProducts= new ArrayList<String>();
protected ArrayList<Integer> price_ofProducts = new ArrayList<Integer>();
protected ArrayList<Integer> Quantity_ofProducts = new ArrayList<Integer>();
protected ArrayList<String> name_ofProductCompany = new ArrayList<String>();
protected ArrayList<Integer> Product_idNumber = new ArrayList<Integer>();
public Product()
{
}
public Product(int price,String name,int Quantity,String company,int id)
{
this.Quantity=Quantity;
this.price = price;
this.name = name;
this.company=company;
this.id=id;
}
Product(ArrayList<Integer> price_ofProducts) {
throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods,choose Tools | Templates.
}
// Setter Method
public void setName(String name) {
this.name = name;
}
public void setPrice(int price) {
this.price = price;
}
public void setQuantity(int Quantity)
{
this.Quantity=Quantity;
}
public void setCompany(String company)
{
this.company=company;
}
public void setId(int id)
{
this.id=id;
}
// Getter Methods
public String getName() {
return name;
}
public int getPrice() {
return price;
}
public int getQuantity()
{
return Quantity;
}
public String getCompany()
{
return company;
}
public int getId()
{
return id;
}
public void dispalyProduct()
{
System.out.println("Name\tPrices\tQuantity\tcompany\tid_no");
for(int i=0;i<name_ofProducts.size();i++)
{
System.out.println((i+1)+")"+name_ofProducts.get(i)+""+price_ofProducts.get(i)+"\t"+Quantity_ofProducts.get(i)+"\t"+name_ofProductCompany.get(i)+"\t"+Product_idNumber.get(i));
}
}
}
我的交易类：
/*
* To change this license header,choose Tools | Templates
* and open the template in the editor.
*/
package project;
import java.util.*;
/**
*
* @author zfhas
*/
public class Transaction extends Product{
private int product_Number;
private int calculation;
public Transaction()
{
}
public void setProduct_Number(int product_Number)
{
this.product_Number=product_Number;
}
public int getProduct_Number()
{
return product_Number;
}
//@SuppressWarnings("resource")
public void Product_Number()
{
/*
Products Display
*/
dispalyProduct();
/*
Declaring Variables
*/
int quantity;
int product_number=0;
/*
Performing Transaction
*/
System.out.println("Enter the Number of product that you want to parchased");
Scanner Input = new Scanner(System.in);
product_number= Input.nextInt();
System.out.println("Product Number is: "+product_number);
System.out.println("Enter Quantity");
quantity = Input.nextInt();
System.out.println("Quantity Entered "+quantity);
//System.out.println(super.price_ofProducts);
switch (product_number)
{
case 1:
try {
System.out.println("Price of Product: " + super.price_ofProducts.get(1-1));
calculation = super.price_ofProducts.get(1-1);
System.out.println(calculation);
calculation(calculation,quantity);
System.out.println("It works.");
} catch (Exception e) {
System.out.println("Error: " + e);
}
break;
case 2:
try {
System.out.println("Price of Product: " + super.price_ofProducts.get(2-1));
calculation = super.price_ofProducts.get(2-1);
calculation(calculation,quantity);
} catch(Exception e) {
System.out.println("Error: " + e);
}
break;
case 3:
try{
System.out.println(super.price_ofProducts.get(3-1));
calculation= super.price_ofProducts.get(3-1);
calculation(calculation,quantity);
} catch(Exception e){
System.out.println("Error: " + e);
}
break;
case 4:
try{
calculation= super.price_ofProducts.get(4-1);
calculation(calculation,quantity);
}
catch(Exception e){
System.out.println("Error: " + e);
}
break;
case 5:
try{
calculation=super.price_ofProducts.get(5-1);
calculation(calculation,quantity);
}catch(Exception e){
System.out.println("Error: " + e);
}
break;
case 6:
try{
calculation=super.price_ofProducts.get(6-1);
calculation(calculation,quantity);
}catch(Exception e){
System.out.println("Error: " + e);
}
break;
default:
System.out.println("you entered wrong number");
break;
}
}
public void calculation(int a,int b)
{
int total;
total = a*b;
billDisplay(total);
}
public void billDisplay(int total)
{
System.out.println("your total bill = "+total);
billrecive(total);
}
public void billrecive(int total)
{
@SuppressWarnings("resource")
Scanner Input = new Scanner(System.in);
int enteredMoney=Input.nextInt();
int i=0;
while(i>1)
{
if(enteredMoney==total)
{
displayRecipt();
break;
}
else if (enteredMoney<total)
{
System.out.print("Enter More= ");
int enteredMoney1=Input.nextInt();
enteredMoney+=enteredMoney1;
continue;
}
else if(enteredMoney>total)
{
enteredMoney=enteredMoney-total;
System.out.println("Your remaining are : "+enteredMoney);
displayRecipt();
break;
}
}
}
public void displayRecipt()
{
System.out.println("billing done");
dispalyProduct();
}
public void addProduts(String name,int price,int quantity,int id)
{
name_ofProducts.add(name);
price_ofProducts.add(price);
Quantity_ofProducts.add(quantity);
name_ofProductCompany.add(company);
Product_idNumber.add(id);
}
}
解决方法
Product p和Transaction tr1是两个完全独立的对象实例。
您在p中设置了所有产品，然后通过tr1查询用户。当您问用户选择哪一个时，tr1没有任何相同的产品数据（或根本没有任何数据）。它只显示产品，因为您致电p.dispalyProduct
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