Question

您好我正在尝试创建一个程序，以便在用户输入特定对象的新信息时创建新对象。目前我有这个。

import java.util.Scanner;
public class Main
{
    public static void main (String args[]) 
{
    String input;
    Scanner scanner = new Scanner(System.in);
    do
    {
        System.out.println("Computer Menu");  
        System.out.println("1. Add a new Desktop Information");
        System.out.println("2. Add a new Laptop Information");
        System.out.println("3. Display all Computer Information");
        System.out.println("4. Quit");

        System.out.print("Please enter either 1 to 4: "); 
        input =(scanner.nextLine());
        if (input.equals("1"))
        {
            Desktop desktop1 = new Desktop();
            System.out.println("Please enter Desktop ID: ");
            desktop1.setID (scanner.nextLine());
            System.out.println("Please enter Desktop Processor Speed: ");
            desktop1.setProcess (Double.parseDouble(scanner.nextLine()));
            System.out.println("Please enter Desktop RAM: ");
            desktop1.setRam (Double.parseDouble(scanner.nextLine()));
            System.out.println("Please enter Desktop Harddisk Space: ");
            desktop1.setDisk (Double.parseDouble(scanner.nextLine()));
            System.out.println("Please enter Desktop Monitor Type: ");
            desktop1.setMonitor (scanner.nextLine());
            System.out.println("Please enter Desktop Price: ");
            desktop1.setPrice (Double.parseDouble(scanner.nextLine()));
            desktop1.displayComputer();
        }
        else if (input.equals("2"))
        {
            Laptop laptop1 = new Laptop();
            System.out.println("Please enter Laptop ID: ");
            laptop1.setID (scanner.nextLine());
            System.out.println("Please enter Laptop Processor Speed: ");
            laptop1.setProcess (Double.parseDouble(scanner.nextLine()));
            System.out.println("Please enter Laptop RAM: ");
            laptop1.setRam (Double.parseDouble(scanner.nextLine()));
            System.out.println("Please enter Laptop Harddisk Space: ");
            laptop1.setDisk (Double.parseDouble(scanner.nextLine()));
            System.out.println("Please enter Laptop Weight: ");
            laptop1.setWeight (Double.parseDouble(scanner.nextLine()));
            System.out.println("Please enter Laptop Price: ");
            laptop1.setPrice (Double.parseDouble(scanner.nextLine()));
            laptop1.displayComputer();
         }

计算机超级

public class Computer
{
    String ID;
    double process;
    double ram;
    double disk;
    double price;

    void setID (String _id)
    {
        ID = _id;
    }
    void setProcess (double _Process)
    {
        process = _Process;
    }
    void setRam (double _Ram)
    {
        ram = _Ram;
    }
    void setDisk (double _Disk)
    {
        disk = _Disk;
    }
    void setPrice (double _Price)
    {
        price = _Price;
    }

    String getID()
    {
        return ID;
    }
    double getProcess()
    {
        return process;
    }
    double getRam()
    {
        return ram;
    }
    double getDisk()
    {
        return disk;
    }
    double getPrice()
    {
        return price;
    }

    void displayComputer()
    {
        System.out.println("Computer ID: " + getID());
        System.out.println("Processor Speed: " + getProcess());
        System.out.println("RAM: " + getRam());
        System.out.println("Harddisk: " + getDisk());
        System.out.println("Price: " + getPrice());
    }
}

桌面子类

public class Desktop extends Computer
{
    String monitor;

    void setMonitor (String _Monitor)
    {
        monitor = _Monitor;
    }
    String getMonitor()
    {
        return monitor;
    }

    void displayComputer()
    {
        System.out.println("Computer ID: " + getID());
        System.out.println("Processor Speed: " + getProcess());
        System.out.println("RAM: " + getRam());
        System.out.println("Harddisk: " + getDisk());
        System.out.println("Monitor Type: " + getMonitor());
        System.out.println("Price: " + getPrice());
        System.out.println("");
    }
}

笔记本电脑子课程

public class Desktop extends Computer
{
    double Weight;

    void setWeight(String _Weight)
    {
        Weight= _Weight;
    }
    String getWeight()
    {
        return Weight;
    }

    void displayComputer()
    {
        System.out.println("Computer ID: " + getID());
        System.out.println("Processor Speed: " + getProcess());
        System.out.println("RAM: " + getRam());
        System.out.println("Harddisk: " + getDisk());
        System.out.println("Weight: " + getWeight());
        System.out.println("Price: " + getPrice());
        System.out.println("");
    }
}

所以有一个班级和2个子班级，但我认为这不重要。因此，如果我输入1，它应该为Desktop创建一个新对象，如果我输入2，它将为Laptop创建一个新对象。当我输入3时，它应该显示所有创建的对象。我不知道如何让他们中的任何一个工作，请帮助。

Answer 1

根据您提供的限制信息，我尝试解决问题：

我没有在Desktop和Laptop类中添加任何属性，在两个类中都覆盖了toString方法，即


public class Laptop {
    public String toString() {
        return "Laptop [getClass()=" + getClass() + ", hashCode()="
                + hashCode() + ", toString()=" + super.toString() + "]";
    }
}


public class Desktop {
    public String toString() {
        return "Desktop [getClass()=" + getClass() + ", hashCode()="
                + hashCode() + ", toString()=" + super.toString() + "]";
    }
}

您的主要方法如下：

public static void main (String args[]) 
    {
        String input;
        Scanner scanner = new Scanner(System.in);
        List<Object> listOfObject = new ArrayList<>();
        do
        {
            System.out.println("Computer Menu");  
            System.out.println("1. Add a new Desktop Information");
            System.out.println("2. Add a new Laptop Information");
            System.out.println("3. Display all Computer Information");
            System.out.println("4. Quit");

            System.out.print("Please enter either 1 to 4: "); 
            input =(scanner.nextLine());
            if (input.equals("1")){
                Desktop desktop1 = new Desktop();
                listOfObject.add(desktop1);
            }else if (input.equals("2")){
                Laptop laptop1 = new Laptop();
                listOfObject.add(laptop1);
             }else if(input.equals("3")){
                 for(Object obj : listOfObject){
                     if(obj instanceof Desktop){
                        Desktop d1 = (Desktop)obj;
                        System.out.println(d1.toString());
                     }else if(obj instanceof Laptop){
                         Laptop l1 = (Laptop)obj;
                         System.out.println(l1.toString());
                     }
                 }
             }
        }while(!input.equals("4"));
    }

Answer 2

假设您有一个名为Computer的类/接口，笔记本电脑和桌面将从该接口扩展。

1）添加一个列表来存储计算机实例。

List<Computer> computers = new ArrayList<Computer>()

2）采取行动＆＃34; 1＆＃34;和＆＃34; 2＆＃34;添加到该列表，例如

computers.add(desktop1);

3）采取行动＆＃34; 3＆＃34;打印出清单。这假设您已实现toString（）

for (Computer computer : computers) {
   System.out.println(computer);
}

使用用户输入创建新对象[JAVA]

2 个答案: