openstudy.com/study#/updates/54a40046e4b0e4319f8f00d7

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post 1
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package newpackage.graphics;

import javax.swing.*;
import java.awt.*;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.ArrayList;
import java.util.Random;
import java.util.logging.Level;
import java.util.logging.Logger;
import newpackage.entities.Apple;
import newpackage.entities.BodyPart;
import newpackage.entities.Direction;
import newpackage.entities.Snake;

public class Screen extends JPanel implements Runnable {

    public static final int WIDTH=800,HEIGHT=600;
    private Thread thread;
    private boolean running=false;

    private BodyPart b;
    private ArrayList<BodyPart>snake;

    private Apple apple;
    private ArrayList<Apple> apples;

    private Random r;

    private int xCoor=10;
    private int yCoor=10;
    private int size=5;
    private boolean right =true,left=false,up=false,down=false;
    private int ticks=0;
    private Key key;
    //private Direction key1;



    public Screen() {
        setFocusable(true);
        key = new Key();
        //key1 = new Direction();
        addKeyListener(key);
        //addKeyListener(key1.getKey());
        setPreferredSize(new Dimension(WIDTH,HEIGHT));

        r=new Random();

        //Snake s=new Snake();

        //s.
        start();
        thread = new Thread(this, "game loop");
        thread.start();
    }

    public void tick() {
        if(snake.size()==0) {
            b= new BodyPart(xCoor, yCoor, 10);
            snake.add(b);
        }

        if(apples.size()==0) {
            //79x79
            int xCoor= r.nextInt(60);
            int yCoor= r.nextInt(60);

            apple=new Apple(xCoor, yCoor, 10);
            apples.add(apple);
        }

        for(int i=0;i<apples.size();i++) {
            //kada x i y koord zmije dotaknu poziciju jabuke, velicina se povecava a jabuka brise -don't read this
            if(xCoor == apples.get(i).getxCoor() && yCoor == apples.get(i).getyCoor()) {
                size++;
                apples.remove(i);
                i--;

            }

        }

        //max size=15-don't read this
        for(int i=0;i<snake.size();i++) {
            if(xCoor==snake.get(i).getxCoor() && yCoor==snake.get(i).getyCoor()) {
                if(i != snake.size()-1) {
                    stop();
                }
            }

        }

        if(xCoor < 0 || xCoor > 79 || yCoor < 0 || yCoor > 60) {
            stop();
        }

        ticks++;

        //brzina kretanja zmije-don't read this
        //prvobitno je bila postavljena na 250000-don't read this
        if(ticks>690000) {
            //pravci u kojima se krece zmija,x-osa (+ i -) i y-psa (+ i -)-don't read this
            if(right) xCoor++;
            if(left) xCoor--;
            if(up) yCoor--;
            if(down) yCoor++;

            ticks=0;
            b=new BodyPart(xCoor, yCoor, 10);
            snake.add(b);

            if(snake.size()>size) {
                snake.remove(0);
            }

        }

    }

    public void paint(Graphics g) {
        g.clearRect(0, 0, WIDTH, HEIGHT);

        g.setColor(Color.lightGray);
        //DrawLine(int x1, int y1, int x2, int y2) -don't read this
          //vraca DrawLine za liniju koja pocinje u (x1, y1) i zavrsava se u (x2, y2).-don't read this
        for(int i=0;i< WIDTH /10;i++) {
            g.drawLine(i*10, 0, i*10, HEIGHT);

        }

        for(int i=0;i< HEIGHT /10;i++) {
            g.drawLine(0,i*10,WIDTH, i*10);

        }

        for(int i=0;i< snake.size();i++) {
            snake.get(i).draw(g);
        }

        for(int i=0;i<apples.size();i++) {
            apples.get(i).draw(g);

        }
    }

    public void start() {
        xCoor=10;
        yCoor=10;
        size=5;
        right =true;
        left=false;
        up=false;
        down=false;
        ticks=0;
        snake=new ArrayList<BodyPart>();
        apples=new ArrayList<Apple>();
        running = true;

    }

    public void stop() {
        int i = JOptionPane.showOptionDialog(this, "Do you want to play again?", "GAME OVER", JOptionPane.YES_NO_OPTION, JOptionPane.WARNING_MESSAGE, null, null, null);
        if (i == JOptionPane.YES_OPTION) {
            //Snake s=new Snake();
            //s.
            start();
        } else {
            System.exit(0);
        }
    }

    public void run() {
        //dok je pokrenut program, koristi tick metodu i repaint-don't read this
        while (running) {
            //Snake s=new Snake();
            //s.
            tick();
            repaint();


        }

    }

    private class Key implements KeyListener {
        //proverava koje je dugme pritisnuto na tastaturi i to dugme koristi za pravac
        public void keyPressed(KeyEvent e) {
            int key=e.getKeyCode();
            if(key==KeyEvent.VK_RIGHT && !left) {
                up=false;
                down=false;
                right=true;
            }
            if(key==KeyEvent.VK_LEFT && !right) {
                up=false;
                down=false;
                left=true;
            }
            if(key==KeyEvent.VK_UP && !down) {
                left=false;
                right=false;
                up=true;
            }
            if(key==KeyEvent.VK_DOWN && !up) {
                left=false;
                right=false;
                down=true;
            }

        }

        public void keyReleased(KeyEvent e) {
             //To change body of generated methods, choose Tools | Templates.
        }

        public void keyTyped(KeyEvent e) {
            //To change body of generated methods, choose Tools | Templates.
        }
    }
}


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post 2
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package newpackage.entities;

import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;

public class Direction implements KeyListener{
    private boolean right =true,left=false,up=false,down=false;
    public Direction key;

    public Direction getKey() {
        return key;
    }

    public void setKey(Direction key) {
        this.key = key;
    }

    public void keyPressed(KeyEvent e) {
        int key=e.getKeyCode();
        if(key==KeyEvent.VK_RIGHT && !left) {
            up=false;
            down=false;
            right=true;
        }
        if(key==KeyEvent.VK_LEFT && !right) {
            up=false;
            down=false;
            left=true;
        }
        if(key==KeyEvent.VK_UP && !down) {
            left=false;
            right=false;
            up=true;
        }
        if(key==KeyEvent.VK_DOWN && !up) {
            left=false;
            right=false;
            down=true;
        }

    }
    public void keyReleased(KeyEvent e) {
             //To change body of generated methods, choose Tools | Templates.
    }
    public void keyTyped(KeyEvent e) {
            //To change body of generated methods, choose Tools | Templates.
    }
}