如何使用数组而不是数组列表使用用户输入创建对象

Question

当我编译执行时，我得到java.lang.ArrayOutOfBoundsException 。 我如何解决它？ 必须使用array而不是arrayList。 这是BlueJ 。 我正在从台式机和笔记本电脑继承方法，而这两个类正在获取计算机中父类的值。

---

import java.util.Scanner;

public class testComputer {
    public static void main(String args[]) {
        String a;
        Scanner scanner = new Scanner(System.in);
        Desktop[] desk = new Desktop[5];
        Laptop[] lap = new Laptop[5];
        int Desk = 0;
        int Lap = 0;

        do {
            System.out.println("*************** Artificial Intelligence Co.***************");
            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.println("***********************************************************");
            System.out.print("Please enter either 1 to 4: ");
            a = scanner.nextLine();

            if (a.equals("1")) {
                desk[Desk] = new Desktop();
                desk[Desk].setDisplayDesktopInfo();
            } else if (a.equals("2")) {
                lap[Lap] = new Laptop();
                lap[Lap].setDisplayLaptopInfo();
            } else if (a.equals("3")) {
                int i = 0;
                for (i = 0; i <= desk.length; i++) {
                    if (desk.length == i) {
                        System.out.println("================Desktop================");
                        desk[i] = new Desktop();
                        desk[i].getDisplayDeskInfo();
                        System.out.println("");
                    } else {
                        System.out.println("Error!");
                    }
                }

                int j = 0;
                for (j = 0; j <= lap.length; j++) {
                    if (lap.length == j) {
                        System.out.println("================Laptop================");
                        lap[j] = new Laptop();
                        lap[j].getDisplayLapInfo();
                        System.out.println("");
                    } else {
                        System.out.println("Error");
                    }
                }
            } else if (a.equals("4")) {
                System.out.println("Good Bye!");
            }
        } while (!a.equals("4"));

    }
}

import java.util.Scanner;
public class Desktop extends Computer
{    
private static final String alphanumeric_regex_pattern = "^[a-zA-Z0-9]*$";
private String Monitor;

public Desktop()
{

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

void setDisplayDesktopInfo()
{
    Scanner scanner = new Scanner(System.in);
    System.out.println("========================================");
    System.out.println("Information for new Desktop");
    System.out.println("========================================");
    System.out.print("What is the Computer ID: " + "");
    setComputerID(scanner.nextLine());
    System.out.print("What is the Processor Speed: " + "");
    setprocessorSpeed(scanner.nextLine());
    System.out.print("What is the RAM: " + "");
    setRAM(scanner.nextLine());
    System.out.print("What is the Harddisk size: " + "");
    setHarddisk(scanner.nextLine());
    System.out.print("What is the Monitor Type: " + "");
    setMonitor(scanner.nextLine());
    System.out.println("");
    System.out.println("Your information has been added successfully.");
    System.out.print("");
}
void getDisplayDeskInfo()
{
    System.out.println("Computer ID: " + getComputerID());
    System.out.println("Processor Speed: " + getprocessorSpeed());
    System.out.println("RAM: " + getRAM());
    System.out.println("Harddisk: " + getHarddisk());
    System.out.println("Monitor: " + getMonitor());
    System.out.print("");
}

}

import java.util.Scanner;
public class Laptop extends Computer
{
private String Weight;

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

void setDisplayLaptopInfo()
{
    Scanner scanner = new Scanner(System.in);
    System.out.println("========================================");
    System.out.println("Information for new Laptop");
    System.out.println("========================================");
    System.out.print("What is the Computer ID: " + "");
    setComputerID(scanner.nextLine());
    System.out.print("What is the Processor Speed: " + "");
    setprocessorSpeed(scanner.nextLine());
    System.out.print("What is the RAM: " + "");
    setRAM(scanner.nextLine());
    System.out.print("What is the Harddisk size: " + "");
    setHarddisk(scanner.nextLine());
    System.out.print("What is the Weight: " + "");
    setWeight(scanner.nextLine());
    System.out.println("");
    System.out.println("Your information has been added successfully.");
    System.out.print("");
}
void getDisplayLapInfo()
{
    System.out.println("Computer ID: " + getComputerID());
    System.out.println("Processor Speed: " + getprocessorSpeed());
    System.out.println("RAM: " + getRAM());
    System.out.println("Harddisk: " + getHarddisk());
    System.out.println("Weight: " + getWeight());
    System.out.print("");
}

}

*************** Artificial Intelligence Co.***************
Computer Menu
1. Add a new Desktop Information
2. Add a new Laptop Information
3. Display all Computer Information
4. Quit
***********************************************************
Please enter either 1 to 4: 1
========================================
Information for new Desktop
========================================
What is the Computer ID: D001
What is the Processor Speed: 3.3GHZ
What is the RAM: 4GB
What is the Harddisk size: 80GB
What is the Monitor Type: CRT

Your information has been added successfully.
*************** Artificial Intelligence Co.***************
Computer Menu
1. Add a new Desktop Information
2. Add a new Laptop Information
3. Display all Computer Information
4. Quit
***********************************************************
Please enter either 1 to 4: 3
If you see this message means you have not done yet!
If you see this message means you have not done yet!
If you see this message means you have not done yet!
If you see this message means you have not done yet!
If you see this message means you have not done yet!
Error
Error
Error
Error
Error
*************** Artificial Intelligence Co.***************
Computer Menu
1. Add a new Desktop Information
2. Add a new Laptop Information
3. Display all Computer Information
4. Quit
***********************************************************
Please enter either 1 to 4: 4
Good Bye!

Answer 1

如果用户选择3，则在显示信息之前您正在创建一台新的笔记本电脑对象，我删除了这些行，并且您的代码将顽固地生成ArrayIndexOutOfBoundsException ，现在此代码是无错误的，其余的一切由您决定，享受。

import java.util.Scanner;

public class testComputer {
    public static void main(String args[]) {
        String a;
        Scanner scanner = new Scanner(System.in);
        Desktop[] desk = new Desktop[5];
        Laptop[] lap = new Laptop[5];
        int Desk = 0;
        int Lap = 0;

        do {
            System.out.println("*************** Artificial Intelligence Co.***************");
        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.println("***********************************************************");
        System.out.print("Please enter either 1 to 4: ");
        a = scanner.nextLine();

        if (a.equals("1")) {
            desk[Desk] = new Desktop();
            desk[Desk].setDisplayDesktopInfo();
            ++Desk;
        } else if (a.equals("2")) {
            lap[Lap] = new Laptop();
            lap[Lap].setDisplayLaptopInfo();
            ++Lap;
        } else if (a.equals("3")) {
            int i = 0;
            for (i = 0; i < desk.length; i++) {

                    System.out.println("================Desktop================");

                    desk[i].getDisplayDeskInfo();
                    System.out.println("");

            }

            int j = 0;
            for (j = 0; j < lap.length; j++) {

                    System.out.println("================Laptop================");

                    lap[j].getDisplayLapInfo();
                    System.out.println("");

            }
        } else if (a.equals("4")) {
            System.out.println("Good Bye!");
        }
    } while (!a.equals("4"));

}

}