Code seems functionally the same as solution but won't pass validation

Question about the task

Snake (part 17)

Java Multithreading, Level 2, Lesson 18

Under discussion

Pasting it here so you don't have to find it in the attached code:

public void move(int x, int y)
{
    SnakeSection head = new SnakeSection(this.getX() + x, this.getY() + y);
    checkBorders(head);
    checkBody(head);
    if(isAlive())
    {
        this.sections.add(0, head);
        if(head.getX() == Room.game.getMouse().getX() && head.getY() == Room.game.getMouse().getY())
        {
            Room.game.eatMouse();
        }
        else
        {
            this.sections.remove(this.sections.size() - 1);
        }
    }
}

The solution appears to contain some inefficient code, that's the only difference between it and my own code that I can find. The solution checks !isAlive instead of isAlive. I always prefer to check for true statements rather than false statements if it doesn't make the code more complicated. In this case checking for isAlive makes the code simpler. But I wonder if the validation is insisting on doing it that way.

Now we'll finish the Snake class.

The snake consists of pieces. Each turn, let's just add one piece at the head,
and delete the last one. This will make the snake appear to slither.
You need to add the piece next to the current head (index 0).
The side you add it to depends on the direction (UP, DOWN, LEFT, RIGHT).

Hint:
a) How do you add a piece of the snake to the top of the sections list?
sections.add(0, new_section);
b) And how do you delete the last one?
sections.remove(sections.size()-1);

We need to implement the move(int dx, int dy) method:
a) check whether the snake slithered out of the room (if so, it dies)
b) check whether the new section coincides with any of the existing pieces of snake (if so, the snake dies)
c) add a new section to the snake (to the head) and remove the last piece from its tail.
d) if the mouse's coordinates match the coordinates of the snake's head, call the eatMouse method on the Room class's static game object.
e) if the snake catches the mouse (the coordinates of the snake's head match the coordinates of the mouse), then you don't need to remove a piece from the tail.

Requirements:

The checkBorders method must be called in the move(int dx, int dy) method.
The checkBody method must be called in the move(int dx, int dy) method.
If the snake is still alive, then we need to add a head and remove the last element from the snake's tail.
If the snake catches a mouse, we need to add a head, but we won't delete the last element.
If the mouse's coordinates match the coordinates of the snake's head, you must call the eatMouse method on the Room class's static game object.

package com.codegym.task.task23.task2312; import java.awt.event.KeyEvent; import java.util.ArrayList; /** * The program's main class. */ public class Room { private int width; private int height; private Snake snake; private Mouse mouse; public Room(int width, int height, Snake snake) { this.width = width; this.height = height; this.snake = snake; game = this; } public Snake getSnake() { return snake; } public Mouse getMouse() { return mouse; } public int getWidth() { return width; } public int getHeight() { return height; } public void setWidth(int width) { this.width = width; } public void setHeight(int height) { this.height = height; } public void setSnake(Snake snake) { this.snake = snake; } public void setMouse(Mouse mouse) { this.mouse = mouse; } /** * The program's main loop. * This is where all the important actions happen. */ public void run() { // Create a KeyboardObserver object and start it. KeyboardObserver keyboardObserver = new KeyboardObserver(); keyboardObserver.start(); // As long as the snake is alive while (snake.isAlive()) { // Does the observer have any key events? if (keyboardObserver.hasKeyEvents()) { KeyEvent event = keyboardObserver.getEventFromTop(); // If 'q', then exit the game. if (event.getKeyChar() == 'q') return; // If "left arrow", then move the figure to the left if (event.getKeyCode() == KeyEvent.VK_LEFT) snake.setDirection(SnakeDirection.LEFT); // If "right arrow", then move the figure to the right else if (event.getKeyCode() == KeyEvent.VK_RIGHT) snake.setDirection(SnakeDirection.RIGHT); // If "up arrow", then move the figure up else if (event.getKeyCode() == KeyEvent.VK_UP) snake.setDirection(SnakeDirection.UP); // If "down arrow", then move the figure down else if (event.getKeyCode() == KeyEvent.VK_DOWN) snake.setDirection(SnakeDirection.DOWN); } snake.move(); // Move the snake print(); // Display the current game state sleep(); // Pause between moves } // Display "Game Over" System.out.println("Game Over!"); } /** * Display the current game state on the screen */ public void print() { // Create an array where we will "draw" the current game state int[][] matrix = new int[height][width]; // Draw all the parts of the snake ArrayList<SnakeSection> sections = new ArrayList<SnakeSection>(snake.getSections()); for (SnakeSection snakeSection : sections) { matrix[snakeSection.getY()][snakeSection.getX()] = 1; } // Draw the head of the snake (4 - if the snake is dead) matrix[snake.getY()][snake.getX()] = snake.isAlive() ? 2 : 4; // Draw the mouse matrix[mouse.getY()][mouse.getX()] = 3; // Display it all on the screen String[] symbols = {" . ", " x ", " X ", "^_^", "RIP"}; for (int y = 0; y < height; y++) { for (int x = 0; x < width; x++) { System.out.print(symbols[matrix[y][x]]); } System.out.println(); } System.out.println(); System.out.println(); System.out.println(); } /** * This method is called when the mouse is eaten */ public void eatMouse() { createMouse(); } /** * Create a new mouse */ public void createMouse() { int x = (int) (Math.random() * width); int y = (int) (Math.random() * height); mouse = new Mouse(x, y); } public static Room game; public static void main(String[] args) { game = new Room(20, 20, new Snake(10, 10)); game.snake.setDirection(SnakeDirection.DOWN); game.createMouse(); game.run(); } private int initialDelay = 520; private int delayStep = 20; /** * The programmer pauses. The length of the pause depends on the length of the snake. */ public void sleep() { try { int level = snake.getSections().size(); int delay = level < 15 ? (initialDelay - delayStep * level) : 200; Thread.sleep(delay); } catch (InterruptedException e) { } } }

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Ibrahim

Level 41 , Sheffield, United Kingdom

28 January 2022, 08:10

Here is my code that passed so you can compare it: SnakeSection snak = new SnakeSection(sections.get(0).getX()+x,sections.get(0).getY()+y); checkBorders(snak); checkBody(snak); if (isAlive){ if (snak.getY() >= Room.game.getHeight() || snak.getX() >= Room.game.getWidth()){ } else { sections.add(0, snak); sections.remove(sections.size() - 1); } if (snak.getY() == Room.game.getMouse().getY() || snak.getX() == Room.game.getWidth()){ Room.game.eatMouse(); sections.add(0, snak); } }