Java - how to implement bullet collision with the enemy?

I try to make a 2d tiled game in Java.

So I have this Bullet class and Gun class which shoots bullets when I press the left mouse button. How to make the enemy to disappear when a number of bullets collide with it?

I think to have a number of bullets let's say 5 and after 5 collisions of the bullets with the enemy I should stop render the enemy, but how implement that collision with enemy?

The bullets are basically a ball (fillOval).

The bullet class

package BunnyFights.Entities.Creatures;

import BunnyFights.Entities.Entity;
import BunnyFights.Handler;
import BunnyFights.gfx.Assets;

import java.awt.*;

public class Bullet extends Entity {


    private Snake snake;
    private float dx, dy;
    private float xSpeed = 1.2f,ySpeed = 1.2f;
    private float speed = 1.5f;
    private boolean isDead;

    public Bullet(Handler handler, float x, float y, int width, int height,int dx,int dy) {
        super(handler, x, y, width, height);

        //destination x and y
        this.dx = dx;
        this.dy = dy;

        //distance from destination
        int distance = distanceFromDestination();

        //set x and y speed
        xSpeed = (dx-x)/distance * speed;
        ySpeed = (dy-y)/distance * speed;
    }

    @Override
    public void tick() {
      if(isDead)
          return;

      //move bullet
       x += xSpeed;
       y += ySpeed;

       //if distance from destination < 1 then, bullet dies
       if(distanceFromDestination() <= 1)
           isDead = true;

    }

    @Override
    public void render(Graphics g) {
        if(isDead)
            return;

        g.setColor(Color.RED);
        g.fillOval((int)(x - handler.getGameCamera().getxOffset()), (int)(y - handler.getGameCamera().getyOffset()), width, height);
    }

    public boolean isDead(){
        return isDead;
    }

    private int distanceFromDestination(){
        int distance = (int) Math.sqrt(Math.pow(x - dx,2) + Math.pow(y - dy,2));

        return distance;
    }

}

The gun class which represent the hero who shoots

package BunnyFights.Entities.Creatures;

import BunnyFights.Entities.Entity;
import BunnyFights.Handler;

import java.awt.*;
import java.util.ArrayList;

public class Gun extends Entity {

    private ArrayList<Bullet> bullets;
    private int bulletWidth = 25,bulletHeight = 25;

    private int fireCoolDown = 30;//player can fire after every 80 ticks
    private int timer;
    private boolean canFire;

    public Gun(Handler handler, float x, float y) {
        super(handler, x, y, 0,0);

        bullets = new ArrayList<Bullet>();
    }

    @Override
    public void tick() {

        //counting fire cool down time, if cannot fire
        if(!canFire) {
            timer++;
            if (timer >= fireCoolDown) {
                timer = 0;
                canFire = true;
            }
        }
        for(Bullet bullet : bullets)
            bullet.tick();

        //remove dead bullets
        for(int i = bullets.size() - 1; i >= 0; i--)
            if(bullets.get(i).isDead())
                bullets.remove(i);
    }

    @Override
    public void render(Graphics g) {
    for(Bullet bullet : bullets)
        bullet.render(g);
    }

    public void fire(float x,float y,int dx,int dy){
        if(!canFire)
            return;

        Bullet b = new Bullet(handler,x,y,bulletWidth,bulletHeight,dx,dy);
        bullets.add(b);
        canFire = false;
    }
}

The enemy class (Snake)

package BunnyFights.Entities.Creatures;

import BunnyFights.Handler;
import BunnyFights.States.GameState;
import BunnyFights.Tiles.Tile;
import BunnyFights.gfx.Assets;

import javax.sql.rowset.spi.XmlReader;
import java.awt.*;
import java.awt.image.BufferedImage;

public class Snake extends Creature {

    private BufferedImage image;
    public Snake(Handler handler, float x, float y) {
        super(handler, x, y, DEFAULT_CREATURE_WIDTH, DEFAULT_CREATURE_HEIGHT);

    }

    @Override
    public void tick() {
       move();
      //  handler.getGameCamera().centerOnEntity(this);

    }

    @Override
    public void render(Graphics g) {

            g.drawImage(image, (int) (x - handler.getGameCamera().getxOffset()), (int) (y - handler.getGameCamera().getyOffset()), width, height, null);
    }

    public void moveToPlayer(Player player) {
        float deltaX = player.getX() - this.getX();
        float deltaY = player.getY() - this.getY();
        float hyp = (float) Math.sqrt(deltaX*deltaX + deltaY*deltaY);

        deltaX /= hyp;
        deltaY /= hyp;

        this.setxMove(deltaX * speed);
        this.setyMove(deltaY * speed);
    }

    public void rotateSnake(Player player) {

        if (((player.getX() < (this.getX()+50)) && (player.getX() > (this.getX()-50))) && player.getY() > this.getY()) {
            image = Assets.snakeFace;
        }
        else if (player.getX() > (this.getX()+50)) {
            image = Assets.snakeRight;
        }
        else {
            image = Assets.snakeLeft;
        }

        if (((player.getX() < (this.getX()+50)) && (player.getX() > (this.getX()-50))) && player.getY() < this.getY()) {
            image = Assets.snakeBack;
        }
    }

    public void snakePlayerRelation(Player player) {
        tick();
        moveToPlayer(player);
        rotateSnake(player);
    }

}