Question

Please please help me with this code please

Purpose: To learn the basics of linked lists

You are to implement 2 classes, Scene and Movie.

Note: Please dont use inbuild linkedList methods and functions

The Scene class has the following fields and methods: p

rivate String event

private Scene nextScene

Public Scene(String event) - A constructor that creates a Scene object with the event set and nextScene set to null

Public Scene(String event, Scene next) - A constructor that creates a Scene object with the event and the nextScene fields set

public Scene getNextScene() - returns the nextScene after the current one

public void setNextScene(Scene newScene) - changes the nextScene to the Scene passed in

public String getEvent() - returns the event from the current scene

Your Movie class has the following fields and methods:

public Scene script- that stores a linked list of Scenes

Public Movie() - A Movie constructor which initializes the script variable to null

public void addScene(String event) - A method that adds a new Scene to the end of the Movie’s script. If there are no Scenes in the script then the Scene added becomes the first Scene in the movie

public void addScene(String event, int pos) - A method that adds a new Scene to the Movie’s script at the position passed in, if there are not at least pos scenes in the movie return and don’t do anything EX: If i try to addScene(“asdf”,8) but there are only 3 scenes in the movie return nothing and don’t add the string Note: The linked list is indexed starting from 0 so we have 0,1,2,3,4...

public Scene removeScene() - A method that removes a Scene from the end of the Movie’s script, and returns the removed object. If there are no Scenes in the script then don’t do anything and return null

public Scene removeScene(int pos) - A method that removes the Scene at the passed in position from the Movie’s script, and returns the removed object. If there is not a Scene at pos then don’t do anything and return null EX: if I try removeScene(8) but there are only 3 scenes in the movie return null Note: The linked list is indexed starting from 0 so we have 0,1,2,3,4...

public String toString() - returns a string where each Scene’s event is separated by a comma and space. Ex: “event1, event2, event3”

You also need to create a Driver class with a main method.

In main:

Create a Movie object

Add Scenes until the Movie is: “Introduction”,”Magic Man”,”Betrayal”,”Climax”,”Evil Defeated”,”Conclusion”

Print out the script of the Movie object using toString()

Remove the “Conclusion” of the Movie

Print out the script of the Movie object using toString()

Add a scene to the end of the movie called “Sequel”

Print out the script of the Movie object using toString()

Remove “Evil Defeated” from the Movie since the sequel retconned it

Print out the script of the Movie object using toString()

Add a Scene called “Prequel” to the beginning of the Movie

Print out the script of the Movie object using toString()

Example Output:

“Introduction”,”Magic Man”,”Betrayal”,”Climax”,”Evil Defeated”,”Conclusion”

“Introduction”,”Magic Man”,”Betrayal”,”Climax”,”Evil Defeated”

“Introduction”,”Magic Man”,”Betrayal”,”Climax”,”Evil Defeated”,”Sequel”

“Introduction”,”Magic Man”,”Betrayal”,”Climax”,”Sequel”

“Prequel”,“Introduction”,”Magic Man”,”Betrayal”,”Climax”,”Sequel”

Answer 1

Hi,

I wrote the whole code in a single class.

class Movie
{
   //Class variables for the Linked List
   private static Scene script;
   private static int numScenes;
  
   public static void main(String [] args)
   {
       System.out.println("/=/=/=/= TESTING /=/=/=/=");
       Movie mov = new Movie();

       //Add Scenes until the Movie is: “Introduction”,”Magic Man”,”Betrayal”,”Climax”,”Evil Defeated”,”Conclusion”
       String[] events = new String[]{"Introduction","Magic Man","Betrayal","Climax","Evil Defeated","Conclusion"};
       for(int i=0; i< events.length; i++)
       {
           mov.addScene(events[i]);
       }
       System.out.println(mov.toString());

       //Remove the “Conclusion” of the Movie
       mov.removeScene();
       System.out.println(mov.toString());

       // Add a scene to the end of the movie called “Sequel”
       mov.addScene("Sequel");
       System.out.println(mov.toString());

       // Remove “Evil Defeated” from the Movie since the sequel retconned it
       mov.removeScene(4);
       System.out.println(mov.toString());

       // Add a Scene called “Prequel” to the beginning of the Movie
       mov.addScene("Prequel", 0);
       System.out.println(mov.toString());
   }
  
   public Movie()
   {
       script = null;
       numScenes = 0;
   }

   public void addScene(String event)
   {
       Scene newScene = new Scene(event);
       if(numScenes == 0)
       {
           script = newScene;
       }
       else
       {
           Scene tempScene = script;
           while(tempScene.nextScene != null)
           {
               tempScene = tempScene.nextScene;
           }
           tempScene.nextScene = newScene;
       }
       numScenes++;
   }
  
   public void addScene(String event, int pos)
   {
       if(numScenes >= pos && pos >= 0)
       {
           Scene newScene = new Scene(event);
           if(numScenes == 0)
           {
               script = newScene;
           }
           else
           {
               Scene tempScene = script;
               if(pos == 0)
               {
                   newScene.nextScene = script;
                   script = newScene;
               }
               else
               {
                   if(pos == numScenes)
                   {
                       // numScenes will be once incremented by addScene(String event) too
                       // So to normalize we decrease it once here
                       addScene(event);
                       numScenes--;
                   }
                   else
                   {
                       int prevPos = pos-1;
                       while(prevPos > 0)
                       {
                           tempScene = tempScene.nextScene;
                           prevPos--;
                       }
                       Scene prevScene = tempScene;
                       Scene nextScene = tempScene.nextScene;
                       prevScene.nextScene = newScene;
                       newScene.nextScene = nextScene;
                   }
               }
           }
           numScenes++;
       }
       else
       {
           System.out.println("Given position should be non-negative and less than or equal to number of scenes.");
       }
   }
  
   public Scene removeScene()
   {
       Scene removedEvent = null;
       if(numScenes > 0)
       {
           if(numScenes == 1)
           {
               removedEvent = script;
               script = null;
           }
           else
           {
               Scene tempScene = script;
               while(tempScene.nextScene.nextScene != null)
               {
                   tempScene = tempScene.nextScene;
               }
               removedEvent = tempScene.nextScene;
               tempScene.nextScene = null;
           }

           numScenes--;
       }
       else
       {
           System.out.println("No scenes to remove");
       }
       return removedEvent;
   }

   public Scene removeScene(int pos)
   {
       Scene removedEvent = null;
       if(numScenes > pos && pos >= 0)
       {
           if(numScenes > 0)
           {
               if(pos == 1)
               {
                   removedEvent = script;
                   script = null;
               }
               else
               {
                   if(pos == numScenes-1)
                   {
                       // numScenes will be once decremented by removeScene() too
                       // So to normalize we increasing it once here
                       removeScene();
                       numScenes++;
                   }
                   else
                   {
                       Scene tempScene = script;
                       int prevPos = pos-1;
                       while(prevPos > 0)
                       {
                           tempScene = tempScene.nextScene;
                           prevPos--;
                       }
                       removedEvent = tempScene.nextScene;
                       // System.out.println("Removing: "+ removedEvent.event);
                       tempScene.nextScene = tempScene.nextScene.nextScene;
                   }
               }

               numScenes--;
           }
           else
           {
               System.out.println("No scenes to remove");
           }
       }
       else
       {
           System.out.println("Given position should be non-negative and less than number of scenes. (If there are 5 scenes, then pos should be between 0 to 4.");
       }
       return removedEvent;
   }
  
   @Override
public String toString() {
       Scene tempScene = script;
       String str = "";
       while(tempScene != null)
       {
           str += "\""+tempScene.event+"\"";
           tempScene = tempScene.nextScene;
           if(tempScene != null)
           {
               str+=",";
           }
       }
       return str;
   }
  
   class Scene
   {
       //Declare class variables
       private Scene nextScene;
       private String event;
      
       public Scene(String e)
       {
           event = e;
           nextScene = null;
       }

       public Scene(String e, Scene next)
       {
           event = e;
           nextScene = next;
       }
      
       public Object getNextScene()
       {
           return nextScene;
       }

       public void setNextScene(Scene newScene)
       {
           nextScene = newScene;
       }

       public String getEvent()
       {
           return event;
       }
   }
}