用Java中的编辑数组替换原始数组

Posted 2023-02-14

【中文标题】用Java中的编辑数组替换原始数组

【英文标题】：Replacing original array with edited array in Java

【发布时间】：2022-01-17 09:33:50

【问题描述】：

一旦数组被编辑（添加或删除电影）并且用户返回主菜单再次列出电影，编辑后的数组不会输出。有没有办法在每次操作完成时替换数组以便打印出一个新数组？输出：https://imgur.com/Etm1uXB

*我们不允许在这个作业中使用 ArrayLists

public static void listMovies()  
    String[]movies = "This is Us","Ghostbusters","Shrek","Interstellar","Pacific Rim";
    
    for(int i=0; i<movies.length; i++) 
        System.out.println((i+1)+") "+movies[i]);
    
    returnToMenu();

private static void addMovies(String[]movies)  
    reenterUser(); 
    String[]moreMovies = new String[movies.length+1];

    for(int i=0; i<movies.length; i++) 
        moreMovies[i]=movies[i];
    
    
    Scanner input = new Scanner(System.in);
    
    System.out.println("Add a movie: ");
    moreMovies[moreMovies.length-1]=input.nextLine();
    System.out.println("You have added a movie!");
    
    System.out.println("This is an updated list of movies available at the rental store: ");
    
        printMovies(moreMovies); 
        returnToMenu(); 

【问题讨论】：

您可能希望为此使用 ArrayList。

没有“原始数组”。您在每次通话时都会创建一个新的。您可能希望将其存储在字段中。

【参考方案1】：

我同意 MAK 成员的观点，就像他在评论中所说的那样，您的代码的理想解决方案是用 ArrayList 实例或 Vector 实例（基本相同）替换数组“电影”，以便您可以添加或删除像你一样的元素。

【讨论】：

正如目前所写，您的答案尚不清楚。请edit 添加其他详细信息，以帮助其他人了解这如何解决所提出的问题。你可以找到更多关于如何写好答案的信息in the help center。

【参考方案2】：

对于使用静态方法的用例，最好的解决方案是拥有一个不在方法之间传递的电影列表。这样，列表始终是最新的，不需要替换，事情也不会消失。当我们这样做时，如果您使用列表List<String> movies 而不是数组String[] movies，您的代码将更易于管理和使用。我在下面添加了 cmets 来解释它是如何工作的：

//Move the movie list outside of the method so it becomes a class variable that every method can use.
//It also needs to be static to match your methods.
//Change the type to a List to allow you to easily add more movies.
public static List<String> movies = new ArrayList<>(Arrays.asList("This is Us", "Ghostbusters", "Shrek", "Interstellar", "Pacific Rim"));

//Call this method whenever you want to print the list
public static void listMovies() 
    //iterate list and print movies, we need to use `movies.size()` to get the length of a list
    for(int i=0; i<movies.size(); i++) 
        //use the "get(i)" method to get a movie form the list
        System.out.println((i+1)+") "+movies.get(i));
    
    //returnToMenu();


//This method does not need an input anymore now that we have a class variable that stores the movies
private static void addMovies()  
    //I am not sure what this line does
    //reenterUser();

    Scanner input = new Scanner(System.in);
    
    System.out.println("Add a movie: ");
    //Add the new movie to the list using the add method "movies.add(value)"
    movies.add(input.nextLine());
    System.out.println("You have added a movie!");
    
    System.out.println("This is an updated list of movies available at the rental store: ");
    
    //Print out the updated movie list:
    listMovies();

    //Return to the menu
    returnToMenu(); 

要打印当前和最新的电影列表，您可以调用更新后的listMovies(); 方法。