java - 为什么在运行示例程序时出现找不到主要方法的错误？

Question

我正在尝试运行一个程序(顺便说一下，这不是我的程序，并且我试图将其理解为初学者学习基本 Java 的一种方式)，但我从 Eclipse 中收到一个错误，指出:

Error: Main method not found in class Door, please define the main method as: public static void main(String[] args) or a JavaFX application class must extend javafx.application.Application

但是，我在那里看到了 public static void main(String[] args)？我首先创建了一个项目名称为“Door”的 Java 项目，选择了“使用执行环境 JRE:JavaSE-1.8”，然后选择了“将项目文件夹用作源文件和类文件的根目录”。然后，我创建了一个 Java 类，其中 Source 文件夹和名称为“Door”，我选择 public 作为修饰符并且没有选择方法 studs。我是否选择了错误的选项？

代码:

import java.awt.*;
import javax.swing.*;
import java.util.*;
import java.io.*;
import java.awt.event.*;
import java.util.Scanner;

public class TestDoor
{
static Door Door1;
static Door Door2;
static Door Door3;

static Scanner input=new Scanner(System.in);

public static void main(String[] args)
{
    Door1=new Door("Enter");
    Door2=new Door("Exit");
    Door3=new Door("Treasure");

    Door1.setOpen();
    Door1.setUnlocked();
    Door3.setOpen();

    boolean done = false;
    int choice;

    do
    {
        chooseDoor();
        choice = input.nextInt();

        switch(choice)
        {
            case 1:
                DOOR1();
                break;
            case 2:
                DOOR2();
                break;
            case 3:
                DOOR3();
                break;
            case 4:
                System.out.println("\n\n---------- Door Status ----------\n");

                if(Door1.isLocked()==true)
                {
                    System.out.print("ENTER door is LOCKED and ");
                }

                else
                {
                    System.out.print("ENTER door is UNLOCKED and ");
                }

                if(Door1.isClosed()==true)
                {   
                    System.out.print("CLOSED\n\n");
                }

                else
                {
                    System.out.print("OPEN\n\n");
                }

                if(Door2.isLocked()==true)
                {
                    System.out.print("EXIT door is LOCKED and ");
                }

                else
                {
                    System.out.print("EXIT door is UNLOCKED and ");
                }

                if(Door2.isClosed()==true)
                {   
                    System.out.print("CLOSED\n\n");
                }

                else
                {
                    System.out.print("OPEN\n\n");
                }

                if(Door3.isLocked()==true)
                {
                    System.out.print("TREASURE door is LOCKED and ");
                }

                else
                {
                    System.out.print("TREASURE door is UNLOCKED and ");
                }

                if(Door3.isClosed()==true)
                {   
                    System.out.print("CLOSED\n\n");
                }

                else
                {
                    System.out.printf("OPEN\n\n");
                }

                System.out.println("---------- Door Status ----------\n");
                break;
            default:
                System.out.println("<<<< Out of choice range select again >>>>\n");
            }

    }while(!done);
}

public static void Choices()
{
    System.out.println("\n--------- choices ---------\n\n");
    System.out.println("1. OPEN door");
    System.out.println("2. CLOSE door");
    System.out.println("3. LOCK door");
    System.out.println("4. UNLOCK door");
    System.out.println("5. Check current door status");
    System.out.println("6. Go Back to choose another door");
    System.out.print("\n\nEnter Choice: ");
}

public static void chooseDoor()
{
    System.out.println("\n\n--------- Choose Your Door --------\n\n");
    System.out.println("1. Enter door");
    System.out.println("2. Exit door");
    System.out.println("3. Treasure door");
    System.out.println("4. All Door Statuses");
    System.out.print("\n\nEnter Choice: ");
}

public static void DOOR1()
{
    int choice;
    boolean done = false;
    do
    {
        Choices();
        choice=input.nextInt();

        /*for(int i=0;i<6;i++)
        {
            System.out.println();
        }*/

        switch(choice)
        {
            case 1:
                Door1.open();
                break;
            case 2:
                Door1.close();
                break;
            case 3:
                Door1.lock();
                break;
            case 4:
                Door1.unlock();
                break;
            case 5:
                if(Door1.isLocked()==true)
                {
                    System.out.println("---------- The ENTER Door Status ----------\n");
                    System.out.print("Door is LOCKED and ");
                }
                else
                {
                    System.out.println("---------- The ENTER Door Status ----------\n");
                    System.out.print("Door is UNLOCKED and ");
                }
                if(Door1.isClosed()==true)
                {   
                    System.out.print("CLOSED\n\n");
                    System.out.println("---------- The ENTER Door Status ----------\n");
                }
                else
                {
                    System.out.printf("OPEN\n\n");
                    System.out.println("---------- The ENTER Door Status ----------\n");
                }
                break;
            case 6:
                done = true;
                break;
            default:
                System.out.print("<<<< Out of choice range select again >>>>\n");
            }
    }while(!done);
}

public static void DOOR2()
{
    int choice;
    boolean done = false;

    do
    {
        Choices();
        choice=input.nextInt();

            /*for(int i=0;i<6;i++)
            {
                System.out.println();
            }*/
        switch(choice)
        {   
            case 1:
                Door2.open();
                break;
            case 2:
                Door2.close();
                break;
            case 3:
                Door2.lock();
                break;
            case 4:
                Door2.unlock();
                break;
            case 5:
                if(Door2.isLocked()==true)
                {
                    System.out.println("---------- The EXIT Door Status ----------\n");
                    System.out.print("Door is LOCKED and ");
                }
                else
                {
                    System.out.println("---------- The EXIT Door Status ----------\n");
                    System.out.print("Door is UNLOCKED and ");
                }
                if(Door2.isClosed()==true)
                {   
                    System.out.print("CLOSED\n\n");
                    System.out.println("---------- The EXIT Door Status ----------\n");
                }
                else
                {
                    System.out.printf("OPEN\n\n");
                    System.out.println("---------- The EXIT Door Status ----------\n");
                }
                break;
            case 6:
                done = true;
                break;
            default:
                System.out.print("<<<< Out of choice range select again >>>>\n");
        }
    }while(!done);
}

public static void DOOR3()
{
    int choice;
    boolean done = false;

            do
            {
                Choices();
                choice=input.nextInt();

                /*for(int i=0;i<6;i++)
                {
                    System.out.println();
                }*/

                switch(choice)
                {
                    case 1:
                        Door3.open();
                        break;
                    case 2:
                        Door3.close();
                        break;
                    case 3:
                        Door3.lock();
                        break;
                    case 4:
                        Door3.unlock();
                        break;
                    case 5:
                        if(Door3.isLocked()==true)
                        {
                            System.out.println("---------- The TREASURE Door Status ----------\n");
                            System.out.print("Door is LOCKED and ");
                        }
                        else
                        {
                            System.out.println("---------- The TREASURE Door Status ----------\n");
                            System.out.print("Door is UNLOCKED and ");
                        }
                        if(Door3.isClosed()==true)
                        {   
                            System.out.print("CLOSED\n\n");
                            System.out.println("---------- The TREASURE Door Status ----------\n");
                        }
                        else
                        {
                            System.out.printf("OPEN\n\n");
                            System.out.println("---------- The TREASURE Door Status ----------\n");
                        }
                        break;
                    case 6:
                        done = true;
                        break;
                    default:
                        System.out.print("<<<< Out of choice range select again >>>>\n");
                }
            }while(!done);
}
}

Answer 1

看起来您复制了一个不完整的示例。您发布的类使用了 Door 类的对象，该类不存在!在您复制的来源中查找其他片段。这里没有 Door 类。