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import java.util.*;
public class MusicPlaylist {
private Queue<String> playlist;
private Stack<String> history;
public MusicPlaylist() {
playlist = new LinkedList<>();
history = new Stack<>();
}
// add song to playlist according to user input
// no return
public void addSong(String songToAdd) {
System.out.print("Enter song name: ");
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 void playSong() {
// 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 void printHistory() {
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();
}
public void clearHistory() {
playlist.clear();
}
// delete from history according to user input, starting either from most recent or oldest history
// return modified history
public void deleteFromHistory(int numToDelete) {
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 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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