init

MusicPlaylist.java

@@ -0,0 +1,95 @@
+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));
+		}
+	}
+	}