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// Nik Johnson
// 1-31-2024
// TA: Andy Ruan
import java.util.*;
// music playlist manager with functionality to add and play songs while keeping track of play history,
// which can be cleared, or deleted from in batches
public class MusicPlaylist {
public static void main(String[] args) {
Scanner console = new Scanner(System.in);
Queue<String> playlist = new LinkedList<>();
Stack<String> history = new Stack<>();
System.out.println("Welcome to the CSE 122 Music Playlist!");
String destination = navigator(console);
while (!destination.equalsIgnoreCase("Q")) {
if (destination.equalsIgnoreCase("A")) {
addSong(console, playlist);
} else if (destination.equalsIgnoreCase("P")) {
playSong(playlist, history);
} else if (destination.equalsIgnoreCase("Pr")) {
printHistory(history);
} else if (destination.equalsIgnoreCase("C")) {
clearHistory(history);
} else if (destination.equalsIgnoreCase("D")) {
deleteFromHistory(console, history);
}
destination = navigator(console);
}
}
// menu function, called initially and after any other functions
// return String for use in main menu loop
public static String navigator(Scanner console) {
System.out.println("(A) Add song");
System.out.println("(P) Play song");
System.out.println("(Pr) Print history");
System.out.println("(C) Clear history");
System.out.println("(D) Delete from history");
System.out.println("(Q) Quit");
System.out.println();
System.out.print("Enter your choice: ");
String destination = console.nextLine();
return destination;
}
// add song to playlist according to user input
// no return
public static void addSong(Scanner console, Queue<String> playlist) {
System.out.print("Enter song name: ");
String songToAdd = console.nextLine();
playlist.add(songToAdd);
System.out.println("Successfully added " + songToAdd);
System.out.println();
System.out.println();
}
// play song at the front of the playlist
// no return
public static void playSong(Queue<String> playlist, Stack<String> history) {
// if user attempts to play song when playlist is empty, throw exception
if (playlist.isEmpty()) throw new IllegalStateException();
String songToPlay = playlist.remove();
System.out.println("Playing song: " + songToPlay);
history.push(songToPlay);
System.out.println();
System.out.println();
}
// print history of played songs
// return unmodified history after printing it
public static void printHistory(Stack<String> history) {
int size = history.size();
// if there is no history and user attempts to print history, throw exception
if (history.isEmpty()) throw new IllegalStateException();
String[] historyArray = new String[size];
if (size != 0) {
for (int i = (size - 1); i >= 0; i--) {
historyArray[i] = history.pop();
System.out.println(" " + historyArray[i]);
}
for (int n = 0; n < size; n++) {
history.push(historyArray[n]);
}
}
System.out.println();
System.out.println();
}
// clear history when called
// return empty history
public static void clearHistory(Stack<String> history) {
history.clear();
}
// delete from history according to user input, starting either from most recent or oldest history
// return modified history
public static void deleteFromHistory(Scanner console, Stack<String> history) {
int size = history.size();
List<String> historyArrayList = new ArrayList<>();
if (!history.isEmpty()) {
for (int i = 0; i < size; i++) {
historyArrayList.add(history.pop());
}
}
System.out.println("A positive number will delete from recent history.");
System.out.println("A negative number will delete from the beginning of history.");
System.out.print("Enter number of songs to delete: ");
int numToDelete = Integer.parseInt(console.nextLine());
int absNum = Math.abs(numToDelete);
if (absNum > size) {
throw new IllegalArgumentException();
}
System.out.println();
if (size != 0 && absNum != 0) {
if (absNum == size) {
historyArrayList.clear();
} else if (numToDelete < 0) {
int lastIndex = size - 1;
for (int n = lastIndex; n >= (size - absNum); n--) {
historyArrayList.remove(n);
}
} else if (numToDelete > 0) {
for (int i = 0; i < numToDelete; i++) {
historyArrayList.remove(0);
}
}
}
for (int n = (historyArrayList.size() - 1); n >= 0; n--) {
history.push(historyArrayList.get(n));
}
}
}
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