Leaderboard bug

import greenfoot.*;  // (World, Actor, GreenfootImage, Greenfoot and MouseInfo)
import java.io.*;
import java.util.ArrayList;
import java.util.Scanner;

/**
 * Write a description of class Highscores here.
 * 
 * @author (your name) 
 * @version (a version number or a date)
 */
public class Highscores extends Actor
{
    ArrayList <Integer> highscores = new ArrayList <Integer>();
    public int n;

    public Highscores(ArrayList <Integer> highscores) {
        this.highscores = highscores;

        GreenfootImage img = new GreenfootImage(500, 500);
        setImage(img);
    }

    /**
     * Act - do whatever the Highscores wants to do. This method is called whenever
     * the 'Act' or 'Run' button gets pressed in the environment.
     */
    public void act() 
    {
    }

    public void highscore() {
        try
        {
            Scanner output = new Scanner (new File ("highscores.txt"));

        
            while (output.hasNext()) { //adds highscores to an arraylist from a file
                highscores.add(output.nextInt());

            }
            sort(highscores, highscores.size());
            int i = 0;
            if (highscores.size() > 5) {
                while (highscores.size() != 5) { //while loop removes highscores if there are more than 5 highscores
                    highscores.remove(i);
                }
            }

            System.out.println(highscores);

            GreenfootImage img = getImage();
            img.clear();

            Font f = new Font("Invasion2000", false, false, 60);
            img.setFont(f);

            img.setColor(Color.WHITE);
            img.drawString("" + highscores, 250, 50);

            setImage(img);
        }
        catch(IOException e)
        {
            System.err.println("Caught IOException: " + e.getMessage());
        }
    }

    public static void sort(ArrayList <Integer> highscores, int n)
    {
        // Base case
        if (n <= 1) 
            return;

        // Sort first n-1 elements
        sort(highscores, n-1 );

        // Insert last element at its correct position
        // in sorted array.
        int last = highscores.get(n-1);
        int j = n-2;

        /*Move elements of arr[0..i-1], that are
        greater than key, to one position ahead
        of their current position */
        while ((j >= 0) && (highscores.get(j) > last))
        {
            highscores.set(j+1, highscores.get(j));
            j--;
        }
        highscores.set(j+1, last);

    }

    /*public void display(ArrayList highscores) {
    GreenfootImage img = getImage();
    img.clear();

    Font f = new Font("Invasion2000", false, false, 60);
    img.setFont(f);

    img.setColor(Color.WHITE);
    img.drawString("" + highscores.get(0), 250, 50);
    img.drawString("" + highscores.get(1), 250, 150);
    img.drawString("" + highscores.get(2), 250, 250);
    img.drawString("" + highscores.get(3), 250, 350);
    img.drawString("" + highscores.get(4), 250, 450);
    setImage(img);
    }*/
}

import greenfoot.*;  // (World, Actor, GreenfootImage, Greenfoot and MouseInfo)
import java.io.*;
import java.util.ArrayList;
import java.util.Scanner;
/**
 * Write a description of class LeaderboardScreen here.
 * 
 * @author (your name) 
 * @version (a version number or a date)
 */
public class LeaderboardScreen extends World
{
    //Highscores h1 = new Highscores(highscores);
    StartButton s1 = new StartButton();
    /**
     * Constructor for objects of class LeaderboardScreen.
     * 
     */
    public LeaderboardScreen()
    {    
        // Create a new world with 600x400 cells with a cell size of 1x1 pixels.
        super(1250, 750, 1, false);

        //addObject(h1, 600, 300);
    }
    //   File rate = new File("highscores.txt");

    /**
     * Act - do whatever the Rate wants to do. This method is called whenever
     * the 'Act' or 'Run' button gets pressed in the environment.
     */
    public void act(int score) 
    {
        try
        {
            //    FileWriter create = new FileWriter(rate);
            //PrintWriter output = new PrintWriter(create);
            PrintWriter input = new PrintWriter(new BufferedWriter(new FileWriter("highscores.txt", true)));

            input.println(score);

            //display();
            input.close();

        }
        catch(IOException e)
        {
            System.err.println("Caught IOException: " + e.getMessage());
        }

    }

    /*public static void highscore() throws java.io.FileNotFoundException {

    Scanner file = new Scanner (new File ("highscores.txt"));

    ArrayList <Integer> highscores = new ArrayList <Integer>();
    for (int i = 0; i < 5; i++) {
    highscores.add(0); //initializes the array with 5 zero's
    }
    while (file.hasNext()) { //adds highscores to an arraylist from a file
    highscores.add(file.nextInt());
    }
    int r = 0;
    if (highscores.size() > 5) {
    while (highscores.size() != 5) { //while loop removes highscores if there are more than 5 highscores
    highscores.remove(r);
    }
    }
    System.out.println(highscores);
    }

    public void display(ArrayList <Integer> highscores) {
    GreenfootImage img = getImage();
    img.clear();

    Font f = new Font("Invasion2000", false, false, 50);
    img.setFont(f);

    img.setColor(Color.WHITE);
    img.drawString("" + highscores, 30, 30);
    setImage(img);
    }*/
}

public void checkHit() {
        if((isTouching(BottomPipe.class)) || (isTouching(TopPipe.class) || (getY() > getWorld().getHeight()))) {
            Greenfoot.playSound("nani.mp3");  
            GameOver g1 = new GameOver(); 
            getWorld().addObject(g1,getWorld().getWidth() /2, getWorld().getHeight()/2);
            City c1 = new City();
            LeaderboardScreen l1 = new LeaderboardScreen();
            l1.act(City.score);

            City.score = 0;

            //StartButton s2 = new StartButton();
            //getWorld().addObject(s2,getWorld().getWidth() /2, getWorld().getHeight()/2 + 150);

            HomeScreen h1 = new HomeScreen();
            getWorld().removeObject(this);
            Greenfoot.delay(75);
            Greenfoot.setWorld(h1);
            //City c1 = new City();
            //LeaderboardScreen l1 = new LeaderboardScreen();
            //l1.act(c1.score);
            //Greenfoot.stop();

        }

        if (counter >= firstPipe) {
            if (counter1 % 110 == 0) {
                score++;
                Greenfoot.playSound("ping.mp3");
                scoreText.setScore(score);

                //}
            }
            counter1++;
        }

java.util.Collections.swap(highScores, j+1, j);