java - 删除用户输入的信息

Question

我正在尝试为一些作业制作一个电影数据库。添加删除功能时遇到困难。由于我的 moivecount 变量，我在尝试重新添加另一部电影时陷入困境。如果我删除 movie3(如果我有 4 部电影)，则 moviecount == 3，当我尝试添加另一部电影时，当我需要添加 movie3 时，它会再次要求 movie4。

import java.util.*;
public class Interface {
private void run() 
{


    Scanner console = new Scanner(System.in);
    Movie m1;
    Movie m2;
    Movie m3;
    Movie m4;

    String name, director;
    int size, duration, option;
    int moviecount = 0;

    m1 = new Movie();
    m2 = new Movie();
    m3 = new Movie();
    m4 = new Movie();

do {
    System.out.println("Import new movie:(0), Delete movie from Database (2), View Movies: (3),  Exit (9): ");
    option = console.nextInt();
    switch(option)
    {
        case 0: 
        if(moviecount == 0)
        {
                System.out.print("First Movie: ");
                name = console.next();
                m1.setName (name);
                System.out.print("Director: ");
                director = console.next();
                m1.setDirector (director);
                System.out.print("Size in MB: ");
                size = console.nextInt();
                m1.setSize(size);
                System.out.print("Duration in minutes: ");
                duration = console.nextInt();
                m1.setDuration(duration);
                moviecount++;
                break;


        }

        else if(moviecount == 1)
        {
                System.out.print("Second Movie: ");
                name = console.next();
                m2.setName (name);
                System.out.print("Director: ");
                director = console.next();
                m2.setDirector (director);
                System.out.print("Size in MB: ");
                size = console.nextInt();
                m2.setSize(size);
                System.out.print("Duration in minutes: ");
                duration = console.nextInt();
                m2.setDuration(duration);
                moviecount++;
                break;
        }

        else  if(moviecount == 2)
        {
                System.out.print("Third Movie: ");
                name = console.next();
                m3.setName (name);
                System.out.print("Director: ");
                director = console.next();
                m3.setDirector (director);
                System.out.print("Size in MB: ");
                size = console.nextInt();
                m3.setSize(size);
                System.out.print("Duration in minutes: ");
                duration = console.nextInt();
                m3.setDuration(duration);
                moviecount++;
                break;
        }

        else  if(moviecount == 3)
        {
                System.out.print("Fourth Movie: ");
                name = console.next();
                m4.setName (name);
                System.out.print("Director: ");
                director = console.next();
                m4.setDirector (director);
                System.out.print("Size in MB: ");
                size = console.nextInt();
                m4.setSize(size);
                System.out.print("Duration in minutes: ");
                duration = console.nextInt();
                m4.setDuration(duration);
                moviecount++;
                break;
        }

        else
        {
                System.out.print("Too many movies currently stored \n" );
                break;
        }

        case 2: System.out.print("Which movie to delete? (1), (2), (3), (4) \n");
        option = console.nextInt();
        switch(option)
        {
           case 1:  m1.setName(null);
                    m1.setDirector(null);
                    m1.setSize(0);
                    m1.setDuration(0);
                    System.out.print("Movie 1 deleted! ");
                    moviecount--;
                    break;           

           case 2:  m2.setName(null);
                    m2.setDirector(null);
                    m2.setSize(0);
                    m2.setDuration(0);
                    moviecount--;
                    break;

           case 3:  m3.setName(null);
                    m3.setDirector(null);
                    m3.setSize(0);
                    m3.setDuration(0);
                    moviecount--;
                    break;

           case 4:  m4.setName(null);
                    m4.setDirector(null);
                    m4.setSize(0);
                    m4.setDuration(0);
                    moviecount--;
                    break;

        }

        case 3: System.out.print("Movies stored in database: \n");
                System.out.print(m1.getName()+"\n"); 
                System.out.print(m2.getName()+"\n");
                System.out.print(m3.getName()+"\n");
                System.out.print(m4.getName()+"\n");










    } 
}
    while(option!=9);



}
public static void main(String[] args){
Interface intFace = new Interface();
intFace.run();
}
}

Answer 1

问题出在你的设计上。您遇到这个问题是因为您实际上并没有将电影存储在任何地方。您只需创建 4 个不同的电影对象并将它们打印出来。如果您更改了打印语句的顺序，它们的顺序将会不同。

您将需要添加某种数据结构 - 任何数组、列表或某种其他类型的集合来存储您的电影。

例如，您可以创建一个列表来存储您的电影数据。

    //create new List called movieList
    List movieList = new ArrayList();

    //add movies to the list
    movieList.add(m1);
    movieList.add(m2);
    movieList.add(m3);
    movieList.add(m4);


    //remove movies from the list by position
    movieList.remove(0);
    movieList.remove(1);
    movieList.remove(2);
    movieList.remove(3);

您可以使用列表的 add() 方法将电影添加到列表中，并使用 remove() 方法将其删除。请记住，remove 会删除您提供的索引处的元素，并且索引从 0 开始。

因此，例如要删除第一部电影，您可以调用 movieList.remove(0)。第二部电影的索引为 1，依此类推。