Can someone please help..

Question about the task

Snake (part 16)

Java Multithreading, Level 2, Lesson 18

Under discussion

I have tried everything and nothing seems to pass validation. Does anyone see what is wrong?

Nothing is forever... That's why the snake must die if it hits a wall or itself.

There's a very simple check to determine whether a snake intersects itself:
does the sections list contain a "new snake's head"?

This is what the code will look like:
if (sections.contains(head))

The head must not be added to the sections list, otherwise this condition will always be true.
But for this code to work, you need to implement object comparison methods (equals and hashCode) in the SnakeSection class.

Hint:
Use Alt+Insert in IntelliJ IDEA to automatically generate equals and hashCode methods.

Task:
a) implement equals and hashCode methods in the SnakeSection class.
b) implement the checkBorders(SnakeSection head) method: if the snake's head is outside the room, the snake dies (isAlive = false)
c) implement the checkBody(SnakeSection head) method: if the snake's head intersects its body, the snake dies (isAlive = false)

Requirements:

The SnakeSection class must have an equals method.
The SnakeSection class must have a hashCode method.
The checkBorders method in the Snake class must be implemented according to the task conditions.
The checkBody method in the Snake class must be implemented according to the task conditions.

package com.codegym.task.task23.task2312; import java.util.List; public class Room { private int width; private int height; private Snake snake; private Mouse mouse; static Room game; public static void main(String[] args) { Snake snake = new Snake(10,10); snake.setDirection(SnakeDirection.DOWN); game = new Room(20,20, snake); game.createMouse(); game.run(); } public Room(int width, int height, Snake snake) { this.width = width; this.height = height; this.snake = snake; } public int getHeight() { return height; } public void setHeight(int height) { this.height = height; } public int getWidth() { return width; } public void setWidth(int width) { this.width = width; } public Snake getSnake() { return snake; } public void setSnake(Snake snake) { this.snake = snake; } public Mouse getMouse() { return mouse; } public void setMouse(Mouse mouse) { this.mouse = mouse; } public void run() { print(); } public void sleep() { int sleepTime = 500; int snakeLength = snake.getSections().size(); int algorithm = (snakeLength - 1) * 20; if (snakeLength > 1 && snakeLength < 12) sleepTime -= algorithm; if (snakeLength > 11 && snakeLength < 16) sleepTime -= algorithm + (5 * (snakeLength - 11)); if (snakeLength > 15) sleepTime = 200; try { Thread.sleep(sleepTime); } catch (InterruptedException e) { e.printStackTrace(); } } public void print() { int[][] roomDisplay = new int[height][width]; List<SnakeSection> sections = snake.getSections(); // add snake location to roomDisplay // head SnakeSection head = snake.getHead(); roomDisplay[head.getY()][head.getX()] = 2; // body for (int i = 0; i < sections.size(); i++) { SnakeSection section = sections.get(i); roomDisplay[section.getY()][section.getX()] = 1; } // add mouse location to roomDisplay roomDisplay[mouse.getY()][mouse.getX()] = 3; // draw the room for (int y = 0; y < height; y++) { StringBuilder sb = new StringBuilder(); for (int x = 0; x < width; x++) { if (roomDisplay[y][x] != 0) { if (roomDisplay[y][x] == 1) sb.append("x"); if (roomDisplay[y][x] == 2) sb.append("X"); if (roomDisplay[y][x] == 3) sb.append("^"); } else { // prints border section if (y == 0 || y == height - 1) sb.append("."); else if (x == 0 || x == width - 1) sb.append("."); else sb.append(" "); } } System.out.println(sb.toString()); } } void createMouse() { int x = (int)(Math.random() * width); int y = (int)(Math.random() * height); mouse = new Mouse(x, y); } void eatMouse() { createMouse(); } }

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June Sung Park

Level 41 , Yangp'yong, Korea, Republic of

10 July 2020, 01:24

A difference between your code and mine which passed the validation lies in the constructor of Snake. Inside the constructor, I still add head to sections, but I do that only if isAlive is true after calling checkBody(head) method. In other words, I add the snake's head to the sections list if it does not intersect with its own body; otherwise, it's killed (i.e., isAlive is set to false by checkBody(head) method). Another difference is that I still have getX() and getY() methods in Snake class which are used in print() method of Room class. If your print() method of Room class does not use them, you may not need them.

Nicolas Huet

Level 41 , Provins, France

21 October 2019, 18:49

import static com.codegym.task.task23.task2312.Room.game;

Find another way to use game in your method, it's the only difference with mine which passed.

Guadalupe Gagnon

Level 37 , Tampa, United States

21 October 2019, 18:43

Try removing the import statement and using: Room.game.getWidth() and Room.game.getHeight() I don't know if this is the "issue" or not, but I can't find any fault in your code.

Nicolas Huet

Level 41 , Provins, France

21 October 2019, 18:50

You are too fast^^

Brandon Horvatic

Level 27 , Johannesburg, South Africa

21 October 2019, 18:56

Hi guys, thank you for you fast responses. I removed the import and added Room.game... and it still fails the third verification..

Seb

Level 41 , Crefeld, Germany

18 January 2020, 13:19

I think that if you have adjusted the checkBorders method according to Nicolas' and Guadalupe's suggestions, then the problem won't be the checkBorders method anymore. I believe that you have slightly changed the Snake's class implementation. I mean - I am not a hundred percent sure, but I think that there should not be a "private SnakeSection head" field in the class. If you adjust the Snake constructor as follows - the extra head field won't be needed: public Snake(int x, int y) { this.sections = new ArrayList<>(); SnakeSection head = new SnakeSection(x, y); this.sections.add(head); this.isAlive = true; } I hope that helps.