I can't find the error, help, please.

import java.util.Scanner; public class BirdSurvey { //main method public static void main(String[] args) { //variable declaration String bird; //create object for BirdSurvey Class BirdSurvey bs=new BirdSurvey(); //create object for scanner class Scanner input= new Scanner(System.in); //prompt user for data of bird System.out.print("Enter the name of bird('done' for stop):"); bird=input.next(); //verify whether the name of bird is done while(!bird.equals("done")) { //add the bird to the BirdSurvey object bs.add(bird); //prompt user for data of bird System.out.print("Enter the name of bird('done' for stop):"); bird= input.next(); } //display the datails of the birds store in the list System.out.println(" the birds store in the list are."); bs.getReport(); //prompt user for a bird name to find its count// System.out.print(" Enter the name of bird:"); bird=input.next(); //display the count result of a bird System.out.println("The number of birds of the" +bird+"type in the list"+bs.getCount(bird)); } } FileBirdSurvey.java public class BirdSurvey { //reference to head node private BirdNode head; //default constructor public BirdSurvey() { //set head to null head= null; } //method of implementation public void add(Object bird) { //if the list is empty if(head==null) head= new BirdNode(bird,null,1); else//if head !=null { //variable to find result boolean isFound= false; //reference to front BirdNode current= head; //repeat the loop to display all items while(current != null && !isFound) { //verify bird info if(current.getBird().equals(bird)) isFound= true; else //go to next node current= current.getNextNode(); } //verify if bird is found if(isFound) current.setCount(current.getCount()+1); else //set new node at the beginning of the list// head= new BirdNode(bird,head,1); } } //getCount method implementation public int getCount(Object bird) { //reference to front BirdNode current= head; //repeat the loop to display all items while(current !=null) { if(current.getBird().equals(bird)) return current.getCount(); //go to next node current= current.getNextNode(); } //return 0 if the bird is not found return 0; } //method to display all items in list //method implementation public void getReport() { //create a reference to the front BirdNode current= head; //repeat loop while(current !=null) { //display item in the list System.out.println("The name of the bid is"+current.getBird()+"and the number of this type of bird is"+current.getCount()+"."); //go to next node current= current.getNextNode(); } } //method to return true if list is empty //isEmpty method implementation public boolean isEmpty() { //return result of (head==null) return(head==null); } //BirdNote class private class BirdNode { //variable declaration private Object BirdName; private BirdNode nextNode; private int count; //default constructor public BirdNode() { birdName= null; nextNode= null; count= 0; } //parameterized constructor public BirdNode(Object newBird,BirdNode nextNewNode, int newCount) { birdName= newBird; nextNode= nextNewNode; count= newCount; } //NextNode method implementation public void setNextNode(BirdNode nextNewNode) { nextNode= nextNewNode; } //get nextnode method implementation public BirdNode getNextNode() { return nextNode; } //bird method implementation public void setBird(String newBird) { birdName= newBird; } //get bird method implementation public Object getBird() { return birdName; } //count method implementation public void setCount(int newCount) { count=newCount; } //get count method implementation public int getCount() { return count; } } }