Java 2d Game-Very strange "bug" in game

Question

I have a very strange bug in my 2d game made using Java. Description of the game: the player can move a rocket sprite with the mouse, and must dodge a rectangle that is going to follow the player and kill the player(by collision). Instead of following the player, it only moves to the beginning coordinates of the player, which is 400,400. It should move to the direction the player goes to. Please help me if you know what is wrong.

Main class:

import javax.swing.*;

public class Main extends JFrame{
    private static final long serialVersionUID = 1L;
    final static int WW = 800;
    final static int WH = 600;
    public Main(){
        setSize(WW,WH);
        setResizable(false);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
        setTitle("Space Game");
        add(new GameClass());
        setVisible(true);
    }
    public static void main(String[] args) {
        new Main();
    }
}

GameClass class:

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class GameClass extends JPanel implements ActionListener, KeyListener{
    private static final long serialVersionUID = 1L;
    Enemy enemy = new Enemy();
    Player player = new Player();

    public GameClass(){
        Timer time = new Timer(15, this);
        time.start();
        this.addKeyListener(this);
        this.setFocusable(true);
        player.openImage();
    }

    public void update(){
        player.update();
        enemy.update();
    }

    public void paintComponent(Graphics g){
        g.setColor(Color.BLACK);
        g.fillRect(0,0,Main.WW,Main.WH);
        player.paint(g);
        enemy.paint(g);
        g.dispose();
    }

    public void actionPerformed(ActionEvent e){
        update();
        repaint();
    }

    public void keyPressed(KeyEvent e){
        if(e.getKeyCode() == KeyEvent.VK_LEFT){
            player.setSpeed(-5);
        }
        else if(e.getKeyCode() == KeyEvent.VK_RIGHT){
            player.setSpeed(5);
        }
        else if(e.getKeyCode() == KeyEvent.VK_UP){
            player.setFly(-5);
        }
        else if(e.getKeyCode() == KeyEvent.VK_DOWN){
            player.setFly(5);
            Player.goDown = true;
        }
    }

    public void keyReleased(KeyEvent e){
        if(e.getKeyCode() == KeyEvent.VK_LEFT || e.getKeyCode() == KeyEvent.VK_RIGHT){
            player.setSpeed(0);
        }
        if(e.getKeyCode() == KeyEvent.VK_UP || e.getKeyCode() == KeyEvent.VK_DOWN){
            player.setFly(0);
            Player.goDown = false;
        }
    }

    public void keyTyped(KeyEvent e){

    }
}

Enemy class:

import java.awt.*;

public class Enemy {
    private int x = -100;
    private int y = -100;
    Player player = new Player();

    public void update(){
        System.out.println(player.getX());
        if(player.getX() < this.x){
            this.x -= 5;
        }
        if(player.getX() > this.x){
            this.x += 5;
        }
        if(player.getY() > this.y){
            this.y += 5;
        }
        if(player.getY() < this.y){
            this.y -= 5;
        }

    }

    public void paint(Graphics g){
        g.setColor(Color.ORANGE);
        g.fillRect(x, y, 50, 50);
    }
}

Player class:

import java.awt.Image;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import java.awt.*;

public class Player {
    private Image image;
    private int player_x = Main.WW/2;
    private int player_xspeed = 0;
    private int player_y = Main.WH/2;
    private int player_yspeed = 0;
    private int flamey = player_y + 100;
    private int flamex;
    private int newx;
    private int newy;
    static boolean goDown = false;

    public Player(){
        newx = player_x;
        newy = player_x;
    }

    public void openImage(){
        try {
            image = ImageIO.read(new File("spaceship.png"));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void paint(Graphics g){
        flamex = player_x + 20;
        g.drawImage(image,player_x,player_y,null);
        g.setColor(Color.YELLOW);
        g.fillRect(flamex, flamey+5, 6, 6);
        g.fillRect(flamex+10, flamey, 6, 6);
        g.fillRect(flamex+10, flamey+15, 6, 6);
        g.fillRect(flamex+20, flamey+5, 6, 6);
    }

    public void update(){
        player_x += player_xspeed;
        player_y += player_yspeed;
        if(flamey < (player_y + 125)){
            if(goDown == false)
                flamey += 5;
            else
                flamey += 10;
        }else
            flamey = player_y + 100;
        newx = player_x;
        newy = player_y;
    }

    public void setSpeed(int speed){
        player_xspeed = speed;
    }

    public void setFly(int speed){
        player_yspeed = speed;
    }

    public int getX(){
        return newx;
    }

    public int getY(){
        return newy;
    }
}

Sorry for bad English, please help me. Any help appreaciated :)

Answer 1

It's because the Player it follows is created inside Enemy via the line:

public class Enemy {
  //...
  Player player = new Player();
  //...
}

so it's a different player instance to the one you are controlling, which is created in GameClass via:

public class GameClass extends JPanel implements ActionListener, KeyListener{
    Enemy enemy = new Enemy();
    Player player = new Player();
    //...
}

You need to inject the controlled player instance either as a constructor parameter on Enemy, e.g.

public class GameClass extends JPanel implements ActionListener, KeyListener{
    Player player = new Player();
    Enemy enemy = new Enemy(player);
    //...
}

public class Enemy {
  //...
  Player player;

  public Enemy(Player player) { this.player = player; }
  //...
}

or via a setter.