Java 创建一个方法，每次调用时打印数组列表的不同随机项？
我正在制作一个模拟媒体播放器程序，允许用户输入、编辑、删除和查看所有曲目。很基本，我知道。但我想添加一个功能，允许在每次选择“播放随机歌曲”时打印数组列表中的随机条目，以模拟音乐播放器的随机播放功能。 所以我的方法是Java 创建一个方法，每次调用时打印数组列表的不同随机项？,java,random,arraylist,indexing,output,Java,Random,Arraylist,Indexing,Output,我正在制作一个模拟媒体播放器程序，允许用户输入、编辑、删除和查看所有曲目。很基本，我知道。但我想添加一个功能，允许在每次选择“播放随机歌曲”时打印数组列表中的随机条目，以模拟音乐播放器的随机播放功能。 所以我的方法是 public void playRandom() { System.out.println("Now Playing: " + *insert code here?* ") } 我有3个代表曲目名称、曲目年份和曲目艺术家的数组列表，但是当我在屏幕上打印时，我希望它以这样的方式
public void playRandom()
{
System.out.println("Now Playing: " + *insert code here?* ")
}
//imports the Random mechanism
import java.util.Random;
//imports the scanner
import java.util.Scanner;
public class MainClass extends UserInput {
public String nextInt;
public static void main(String[] args) {
//Links to the UserInput class to create an object that stores
//user input
UserInput ui = new UserInput();
//Creates new scanner object
Scanner input = new Scanner(System.in);
//Declares the int "opt" so it can be used in the menu
int opt;
//Calls Methods Class so methods can be used below
Methods methodsFunctions = new Methods();
//initial prompt only displayed when program is first ran
System.out.println("Welcome to your music library");
//Usig a do while loop so that the program keeps running until
//a specific condition is met, in this case it's when 0 is selected.
do
{
//Menu Prompts printed to the screen for the user to select from
System.out.println("........ \n");
System.out.println("Press 0 to Exit\n");
System.out.println("Press 1 to Add a Song\n");
System.out.println("Press 2 to View All Songs\n");
System.out.println("Press 3 to Remove a Song\n");
System.out.println("Press 4 to Edit Song Information\n");
System.out.println("Press 5 to Play Random Song\n");
System.out.println("Press 6 to Delete All Songs\n");
//Monitors the next Int the user types
opt = input.nextInt();
//"if" statements
if (opt == 0)
{
//This corresponds to the condition of the while loop,
//The program will exit and print "Goodbye!" for the user.
System.out.println("Goodbye!");
}
else if (opt == 1)
{
//This method allows the user to add a song to the library.
//With the format being Title, Artist, Year.
methodsFunctions.addEntry();
}
else if (opt == 2)
{
//This method prints the contents of the Array List to the screen
methodsFunctions.viewAll();
}
else if (opt == 3)
{
//This method allows the user to remove an indiviual song from
//their music library
methodsFunctions.removeOne();
}
else if (opt == 4)
{
//This method allows the user to edit the data of a particular
//and then prints the new value on screen
methodsFunctions.editItem();
}
else if (opt == 5)
{
//This method will print out "Now playing" followed by a random
//song to simulate a music player's shuffle effect.
//methodsFunctions.RandomSong();
System.out.println("Now Playing ");
}
else if (opt == 6)
{
//This method will clear all contents of the library.
//It will ask the user to confirm their choice.
methodsFunctions.clearAll();
}
else
{
//If the user selects an incorrect number, the console will
//tell the user to try again and the main menu will print again
System.out.println("Incorrect Entry, please try again");
}
} //do-while loop
while (opt > 0);
}
}
package ca1;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.Scanner;
public class Methods extends UserInput
{
Scanner input = new Scanner (System.in);
//Declare array lists
List<String> songName = new ArrayList<>();
List<String> songArtist = new ArrayList<>();
List<Integer> songYear = new ArrayList<>();
UserInput ui = new UserInput();
private Random newRandom;
public void clearAll(){
System.out.println("Are you sure?");
System.out.print("1: Yes \n2: No" + "\n");
System.out.print("");
int confirmDelete=input.nextInt();
if (confirmDelete == 1){
songName.clear();
songYear.clear();
System.out.println("Your music library has been cleared");
}
}
public void viewAll(){
System.out.println("\n");
for (int i = 0; i < songName.size(); i++){
int counter=i+1;
System.out.println(counter+": "+songArtist.get(i)+" - "+ songName.get(i)+ " (" +songYear.get(i)+") ");
}
System.out.println("\n");
}
public void addEntry(){
//System.out.print("Enter Name: ");
String newName = ui.getString("Enter the name of the track");
songName.add(newName);
String newArtist = ui.getString("Who performs this track");
songArtist.add(newArtist);
System.out.print("What year was the track released? ");
int newYear=input.nextInt();
songYear.add(newYear);
System.out.println("\n" + "Thank you, " +songName.get(songName.size()-1) + " has been added to the library.");
System.out.println("\n" + "Press 2 to view your library." + "\n");
/*
System.out.println("\n"+songName.get(songName.size()-1));
System.out.println("\n"+songArtist.get(songArtist.size()-1));
System.out.println("\n"+songYear.get(songYear.size()-1));
*/
}
public void removeOne(){
System.out.println(" Which song would you like to delete? (1 to "+songName.size()+")");
viewAll();
int remove=input.nextInt();
if (remove >songName.size()){
System.out.println("Invalid ");
}
else {
remove--;
System.out.println("Are you sure you would like to delete "+songArtist.get(remove)+" - "+songName.get(remove)+" (" +songYear.get(remove)+ ") from your music library?");
System.out.print("1: Yes \n2: No" + "\n");
int confirmDelete=input.nextInt();
if (confirmDelete == 1){
songArtist.remove(remove);
songName.remove(remove);
songYear.remove(remove);
System.out.println(songName.get(remove)+ " has just been removed from your music library");
// viewAll();
}
}
}
public void playRandom()
{
String RandomSong = (SongName.random);
System.out("Now playing + " RandomSong);
}
public void editItem(){
viewAll();
System.out.println("Choose the song you want to edit (1 to "+songName.size()+")");
//prints out the contents of library with first entry being index 1
//The library is numbered and goes as far as the index of the last entry
int edit=input.nextInt();
if (edit >songName.size()){
System.out.println("Invalid Selection");
//if user selects a number that corresponds to an index that's not
//In the array list, they will be shown an error.
}
else{
edit--;
System.out.println("\n" + "Enter New Track Name: ");
input.nextLine();
String editName=input.nextLine();
songName.set(edit,editName);
//Edits the songName value of the Song object selected
System.out.println("\n" + "Enter New Artist ");
String editArtist=input.nextLine();
songArtist.set(edit,editArtist);
//Edits the songArtist value of the Song object selected
System.out.println("\n" + "Enter New Year:");
int editYear;
editYear = input.nextInt();
songYear.set(edit,editYear);
//Edits the songName value of the Song object selected
System.out.print("\n" + "Your changes have been saved:" + "\n");
System.out.print("\n" + "This is your current library");
viewAll();
}
}
}
包装ca1；
导入java.util.ArrayList；
导入java.util.List；
导入java.util.Random；
导入java.util.Scanner；
公共类方法扩展了UserInput
{
扫描仪输入=新扫描仪（System.in）；
//声明数组列表
List songName=new ArrayList（）；
List songArtist=new ArrayList（）；
List songYear=新数组列表（）；
UserInput ui=newuserinput（）；
私有随机新随机；
public void clearAll（）{
System.out.println（“你确定吗？”）；
系统输出打印（“1:是\n2:否”+“\n”）；
系统输出打印（“”）；
int confirmDelete=input.nextInt（）；
如果（confirmDelete==1）{
songName.clear（）；
宋年；
System.out.println（“您的音乐库已被清除”）；
}
}
public void viewAll（）{
System.out.println（“\n”）；
对于（int i=0；isongName.size（））{
System.out.println（“无效”）；
}
否则{
删除--；
System.out.println（“您确定要从您的音乐库中删除“+SongArtister.get（remove）+”-“+songName.get（remove）+”（“+songYear.get（remove）+”）吗？”）；
系统输出打印（“1:是\n2:否”+“\n”）；
int confirmDelete=input.nextInt（）；
如果（confirmDelete==1）{
歌曲艺术家。移除（移除）；
songName.remove（移除）；
宋年。移除（移除）；
System.out.println（songName.get（remove）+“刚刚从音乐库中删除”）；
//viewAll（）；
}
}
}
公共图书馆
{
String RandomSong=（SongName.random）；
系统输出（“正在播放+”随机歌曲）；
}
公共无效编辑项（）{
viewAll（）；
System.out.println（“选择要编辑的歌曲（1到“+songName.size（）+”））；
//打印出库的内容，第一个条目是索引1
//该库已编号并一直到最后一个条目的索引
int edit=input.nextInt（）；
如果（编辑>songName.size（））{
System.out.println（“无效选择”）；
//如果用户选择了一个与索引不一致的数字
//在数组列表中，它们将显示一个错误。
}
否则{
编辑--；
System.out.println（“\n”+”输入新曲目名称：”）；
input.nextLine（）；
String editName=input.nextLine（）；
songName.set（编辑，编辑名称）；
//编辑选定乐曲对象的songName值
System.out.println（“\n”+“输入新艺术家”）；
字符串editArtist=input.nextLine（）；
songArtist.set（编辑，编辑艺术家）；
//编辑选定歌曲对象的SongArtister值
System.out.println（“\n”+”进入新年：”；
国际编辑年；
editYear=input.nextInt（）；
songYear.set（编辑，编辑年）；
//编辑选定乐曲对象的songName值
System.out.print（“\n”+”您的更改已保存：“+”\n”）；
System.out.print（“\n”+“这是您当前的库”）；
viewAll（）；
}
}
}
public void playRandom()
{
int randomnumber =(int)(Math.random() * (length-1));
System.out.println("Now Playing: " + arrayOfSongName[randomnumber]);
}