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gummyw0rm

Fri Mar 15, 2019 9:56 pm


convert switch into an if/else statement

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hi guys i want to switch this code into an if/else statements but am having trouble...


import java.util.Scanner;

public class Playlist {
	public static String title;
	static Scanner scnr = new Scanner(System.in);

	public static void main(String[] args) {  
		Scanner sc=new Scanner(System.in);
		SongEntry song;

		System.out.println("Enter playlist's title:\n");
		title = sc.nextLine();

		song = new SongEntry();

		printMenu(song, sc);


	} 

	public static void menu() {
		System.out.println(title + " PLAYLIST MENU");
		System.out.println("a - Add song");
		System.out.println("d - Remove song");
		System.out.println("c - Change position of song");
		System.out.println("s - Output songs by specific artist");
		System.out.println("t - Output total time of playlist (in seconds)");
		System.out.println("o - Output full playlist");
		System.out.println("q - Quit");
		System.out.println("");
	}

	public static void printMenu(SongEntry songList, Scanner scnr)
	{
		String choice;
		String uniqueID, songName, artistName;
		int songLength;
		boolean select = true;

		SongEntry headObj;
		SongEntry currentObj;
		SongEntry lastObj;

		headObj = new SongEntry();
		lastObj = headObj;

		while(true) {
			menu();

			do {
				System.out.println("Choose an option:");
				choice = scnr.next().trim();

				switch(choice.charAt(0))
				{
				case 'q':
					select = false;                          
					return;
				case 'a':
					scnr.nextLine();    // remove newline character from keyboard
					System.out.println("ADD SONG");
					System.out.println("Enter song's unique ID:");
					uniqueID = scnr.nextLine();
					System.out.println("Enter song's name:");
					songName = scnr.nextLine();
					System.out.println("Enter artist's name:");
					artistName = scnr.nextLine();
					System.out.println("Enter song's length (in seconds):");
					songLength = Integer.parseInt(scnr.nextLine());
					System.out.println("");

					SongEntry song = new SongEntry();
					song.setUniqueID(uniqueID);
					song.setSongName(songName);
					song.setArtistName(artistName);
					song.setSongLength(songLength);
					song.setNext(song);

					// Add the item to linked list
					song.addSong(song);
					lastObj.insertAfter(song);
					lastObj = song;

					menu();
					break;
				case 'd':
					scnr.nextLine();
					System.out.println("REMOVE SONG");
					System.out.println("Enter song's unique ID:");
					uniqueID = scnr.nextLine();

					currentObj = headObj;
					lastObj.deleteSong(currentObj, uniqueID);

					menu();
					break;                
				case 'c':
					scnr.nextLine();   
					System.out.println("CHANGE POSITION OF SONG");
					System.out.println("Enter song's current position:");
					int position = scnr.nextInt();
					System.out.println("Enter new position for song:");
					int newPosition = scnr.nextInt();
					lastObj.changeSongPosition(headObj, position, newPosition);

					menu();
					break;
				case 's':
					scnr.nextLine();
					System.out.println("OUTPUT SONGS BY SPECIFIC ARTIST");
					System.out.println("Enter artist's name:");
					String artistID = scnr.nextLine();                          
					lastObj.findArtist(headObj, artistID);

					menu();
					break;
				case 't':
					scnr.nextLine();     
					System.out.println("OUTPUT TOTAL TIME OF PLAYLIST (IN SECONDS)");
					lastObj.totalTime(headObj);

					menu();
					break;
				case 'o':
					int count = 0;
					currentObj = headObj;
					currentObj = currentObj.getNext(); 
					System.out.println(title + " - OUTPUT FULL PLAYLIST");
					while (currentObj != null) {
						count++;

						currentObj.printSongEntry(currentObj, count);
						currentObj = currentObj.getNext();
					}
					if (count == 0) {
						System.out.println("Playlist is empty\n");
					}

					menu();
					break;                
				} 

			} while (!choice.equals('q'));
		} 

	}

} 



----this is my SongEntry class-----
public class SongEntry {

   // Private fields
   private String uniqueID;      
   private String songName;
   private String artistName;
   private int songLength;
   private SongEntry headNode;       
   private SongEntry currNode;       
   private SongEntry nextNode; 
          
   // Default constructor
   public SongEntry() 
   {
       uniqueID = "none";
       songName = "none";
       artistName = "none";
       songLength = 0;        
   }
  
   // Parameterized constructor
   public SongEntry(String uniqueID, String songName, String artistName, int songLength) {
	  
	   this.uniqueID = uniqueID;
	   this.songName = songName;
	   this.artistName = artistName;
	   this.songLength = songLength;

   }

   public String getID() {
       return uniqueID;
   }
  
   public String getSongName() {
       return songName;
   }
  
   public String getArtistName() {
       return artistName;
   }

   public int getSongLength() {
       return songLength;
   }
   
   public SongEntry getNext() {
       return this.nextNode;
   }
  
   public SongEntry getHead() {
       return this.headNode;
   }
  
   public SongEntry getCurrNode() {
       return this.currNode;
   }

   public void printSongEntry(SongEntry currObj, int count) {      
       System.out.println(count + ".");
       System.out.println("Unique ID: " + this.uniqueID);
       System.out.println("Song Name: " + this.songName);
       System.out.println("Artist Name: " + this.artistName);
       System.out.println("Song Length (in seconds): " + this.songLength);
       System.out.println("");
       return;
   }
   
   public void insertAfter(SongEntry currNode) {
       SongEntry tmpNext;
      
       tmpNext = this.nextNode;
       this.nextNode = currNode;
       currNode.nextNode = tmpNext;
       return;
   }
  
   public void addSong(SongEntry songList) {
       
       SongEntry headObj;   
       SongEntry lastObj;
      
       headObj = new SongEntry();
       lastObj = headObj;      
       lastObj.insertAfter(songList);      
   }
  
   public SongEntry isEmpty() {
       return headNode = null;
   }
 
   public int length(SongEntry head) {
       if (head == null) {
           return 0;
       }
    
       int count = 0;
     
       SongEntry currNode = head;
       while(currNode != null) {
           count++;
           currNode = currNode.getNext();
       }
       return count;
   }
  
   public int findPosition(SongEntry head, String songID) {
       int position = -1;
       int count = 0;
       boolean find = false;
       SongEntry currNode = head;
       int length = length(head);     
       while (find != true) {
           count++;  
           if (count == length - 1) {
               find = true;
           }          
           currNode = currNode.getNext();          
           if (currNode.getID().equals(songID)) {
               position = count;  
               find = true;
           }
       }
       return position;
   }
  
   public String deleteSong(SongEntry head, String songID) {
       
       String songRemoved = "";
       int position = findPosition(head, songID);      
      
       int length = length(head);
       if(position > length || position < 1) { 
           System.out.println("Song not found");
       } 
       else {
      
           SongEntry prevNode = head;
           int count = 1;
               while(count < position ) {
                   prevNode = prevNode.nextNode;
                   count++;
               }
          
           SongEntry curNode = prevNode.nextNode;
           songRemoved = curNode.getSongName();
           prevNode.nextNode = curNode.nextNode;
           curNode.nextNode = null;
           System.out.println(""" + songRemoved + """ + " removed.");
           System.out.println("");
           }
       return songRemoved;
                                          
   } 

   public SongEntry getIndex(SongEntry head, int currPos) {
       if (currPos == 0) return null;

       SongEntry entry = head;
       for (int i = 0; i < currPos; ++i) {
           entry = entry.getNext();
       }
       return entry;
   }
   
  
   public SongEntry changeSongPosition(SongEntry head, int currentPos, int newPos) {
       SongEntry linkedList = head;
       int length = length(head);
       SongEntry currNode = getIndex(linkedList, currentPos);
       String songName = currNode.getSongName();
       SongEntry prevNode = getIndex(linkedList, newPos);
       String prevSongName = prevNode.getSongName();
       System.out.println("Current song is " + songName + " and previous song name is " + prevSongName);
      
       if(newPos < 1)
    	   newPos = 1;
       
       if (head==null){
           return head;
        }
      
        int count = 0;
        while(count < newPos) 
        {
           count++;
        }
      
       return head;
   } 
   public String removeSong(SongEntry head, String songID) { //delete a song
       String songRemoved = "";
       int position = findPosition(head, songID);      
       
       SongEntry prevNode = head;
       int count = 1;
       while(count < position ) {
           prevNode = prevNode.nextNode;
           count++;
       }
      
       SongEntry curNode = prevNode.nextNode;
       songRemoved = curNode.getSongName(); //get name of song
       prevNode.nextNode = curNode.nextNode;
       
       curNode.nextNode = null;
       return songRemoved;     
   } 
  
   public void findArtist(SongEntry head, String artistName) {
       int count = 0;     
       SongEntry currNode = head;  
       while(currNode != null) {
           if(currNode.getArtistName().equals(artistName)) {
               currNode.printSongEntry(currNode, count);
           }
           currNode = currNode.nextNode;
           count++;
       }
   }
  
   public void totalTime(SongEntry head) {
       int time = 0;
       SongEntry currentNode = head;  
       while(currentNode != null) {
           currentNode = currentNode.getNext();
           if (currentNode != null) {
           time = time + currentNode.getSongLength();  
           }  
       }
      
       System.out.println("Total time: " + time + " seconds");                  
       System.out.println("");
   }
   public void setUniqueID(String setUniqueID) {
       this.uniqueID = setUniqueID;
   }
  
   public void setSongName(String setSongName) {
       this.songName = setSongName;
   }
  
   public void setArtistName(String setArtistName) {
       this.artistName = setArtistName;
   }
  
   public void setSongLength(int setSongLgth) {
       this.songLength = setSongLgth;
   }
   public void setNext(SongEntry nextLoc) {
       this.nextNode = nextLoc;
   }
}