为什么我的代码总是出现“Indexoutofbounds”错误？

Question

这是我第一次，请多多包涵。 我正在为一个学校项目创建一个java流媒体服务应用程序，您可以在其中从给定的目录创建不同电影和系列的播放列表。我为菜单创建了一个用于创建播放列表的方法，但我不断收到“Indexoutofbounds”错误。

这是创建播放列表的菜单方法：

void createPlayListMenu() {
        System.out.println();
        System.out.println("CREATE PLAYLIST -----------------");
        System.out.print("Name of your playlist: ");

        
        String name = In.nextLine();
        int playListID = this.videoPlayer.createNewPlayList(name);

        
        PlayList p = this.videoPlayer.getPlayList(playListID);

        while (true) {
            System.out.println("What would you like to do?");
            System.out.println("  1. Add a movie");
            System.out.println("  2. Add a Series");
            System.out.println("  3. Save the playlist");
            System.out.println();

            
            int choice = In.nextInt();

            if (choice == 1) {
                PlayList movies = this.videoPlayer.listMovies();
                this.videoPlayer.displayPlayList(movies);

                int movieChoice = In.nextInt();
                if (movieChoice >= 0 && movieChoice < movies.trackIndexes.size()) {
                    p.addMovieOrSeries(movies.trackIndexes.get(movieChoice));
                    System.out.println("Added " + this.videoPlayer.getTrack(movies.trackIndexes.get(movieChoice))
                            + " to playlist");
                } else {
                    System.out.println("Invalid movie choice");
                }
            } else if (choice == 2) {
                PlayList series = this.videoPlayer.listSeries();
                this.videoPlayer.displayPlayList(series);

                int seriesChoice = In.nextInt();
                if (seriesChoice >= 0 && seriesChoice < series.trackIndexes.size()) {
                    p.addMovieOrSeries(series.trackIndexes.get(seriesChoice));
                    System.out.println("Added " + this.videoPlayer.getTrack(series.trackIndexes.get(seriesChoice))
                            + " to playlist");
                } else {
                    System.out.println("Invalid series choice");
                }
            } else if (choice == 3) {
                System.out.println("Added " + p.name + " to playlist");
                break;
            } else {
                System.out.println("Pick an option 1, 2, or 3");
            }
        }
    }

每当我尝试运行代码时，都会收到此错误：

Exception in thread "main" java.lang.IndexOutOfBoundsException: Index 2 out of bounds for length 1
        at java.base/jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:64)
        at java.base/jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:70)
        at java.base/jdk.internal.util.Preconditions.checkIndex(Preconditions.java:266)
        at java.base/java.util.Objects.checkIndex(Objects.java:361) 
        at java.base/java.util.ArrayList.get(ArrayList.java:427)    
        at VideoPlayer.getPlayList(App.java:466)
        at App.createPlayListMenu(App.java:133)
        at App.userPlayListsMenu(App.java:112)
        at App.runMainMenu(App.java:35)
        at App.main(App.java:14)

如果您需要更多详细信息或其余代码，我可以提供。

Answer 1

索引越界异常意味着您正在尝试访问超出数组范围的索引。在我看来，您对 createNewPlaylist 的调用返回 2 作为 id，但视频播放器内部的 ArrayList 的长度只有 1。

该错误可能存在于您的 VideoPlayer 类中。当您调用 createNewPlayList 时，ArrayList 现在会适当增长，或者返回的索引不正确。由于您在此代码片段中只调用了一次 createNewPlaylist，我猜问题是后者 - 在这种情况下索引可能应该是 0 而不是 2。