java - Shuffle 在 Java 中不工作

Question

我正在尝试为一个项目编写代码。该项目包括添加、删除、打乱和重新排序(移动)字符串。 我目前陷入随机播放状态。我正在使用 import java.util.Collections 并且我陷入困境。我的意思是通过使用下面的代码我得到一个异常:

private static void ShuffleTrack(int[] array) {
    Collections.swap(mp3Player, 0, 1);  
    System.out.println(""+mp3Player);
}

这是我遇到的异常:

Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
    at java.util.ArrayList.rangeCheck(ArrayList.java:653)
    at java.util.ArrayList.get(ArrayList.java:429)
    at java.util.Collections.swap(Collections.java:497)
    at mp3Player.ShuffleTrack(mp3Player.java:78)
    at mp3Player.main(mp3Player.java:40)

我在实际程序中没有收到任何错误，只是在控制台中收到任何错误。

这是代码

import java.util.Scanner;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;

public class mp3Player {
public static Scanner in=new Scanner(System.in);

public static ArrayList<Track> mp3Player = new ArrayList<Track>();

public static void main(String[] args ){
    //declare variables
    int menu = 0;

do{ 
    System.out.println("***WELCOME***");
    System.out.println(" This is my MP3 Album ");
    System.out.println("Please Choose one of the following options:");
    System.out.println("1.Add a Track");
    System.out.println("2.Search for a Track");
    System.out.println("3.Delete an exisiting Track");
    System.out.println("4.Shuffle Tracks");
    System.out.println("5.Reorder Tracks");

    menu = in.nextInt(); //Record user choice

    switch(menu){
    case 1:
        InsertTrack();
        break;

    //case 2:
        //SearchTrack();
    //  break;

    //case 3: 
        //DeleteTrack();
        //break;

    case 4: 
        ShuffleTrack(null);
        //break;

    case 5:
        //ReorderTrack();
        //break;


    }//end of switch

} while(menu !=0); //End of loop

} // End of static void

private static void InsertTrack(){

    Track newtrack = new Track();

    System.out.println("Track Number: ");
    int Tracknumber = in.nextInt();

    System.out.println("Artist Name: ");
    String TrackArtist = in.next();

    System.out.println("Track Name: ");
    String TrackName = in.next();

    System.out.println("Track Duration: ");
    String TrackDuration = in.next();

    System.out.println("Your Track has been added.");

    newtrack.setTrack(Tracknumber, TrackArtist, TrackName, TrackDuration);

}//End of InsertTrack

private static void ShuffleTrack(int[] array){

    Collections.shuffle(Arrays.asList(mp3Player));

    }//End Of ShuffleTrack  


    //Set Attributes
    private String InsertTrack ="";
    private String SearchTrack ="";
    private String DeleteTrack = "";
    private String ShuffleTrack = "";
    private String ReorderTrack = "";

    // Setting Methods
    public void setMp3(String InsertTrack, String SearchTrack, String DeleteTrack, String ShuffleTrack, String ReorderTrack){


        this.InsertTrack = InsertTrack;
        this.SearchTrack = SearchTrack;
        this.DeleteTrack = DeleteTrack;
        this.ShuffleTrack = ShuffleTrack;
        this.ReorderTrack = ReorderTrack;

    }// End of Method

    public String getInsertTrack(){
        return InsertTrack;
    }
    public String getSearchTrack(){
        return SearchTrack;
    }
    public String getDeleteTrack(){
        return DeleteTrack;
    }
    public String getShuffleTrack(){
        return ShuffleTrack;
    }
    public String ReorderTrack(){
        return ReorderTrack;
    }

}//类(class)结束

Answer 1

为什么不简单地使用Collections.shuffle()？

它看起来像这样:

Collections.shuffle(Arrays.asList(array));