snake not biting itself

[Xyexs]

So a couple of days ago i figured i should try making snake (genius) with my noooby programming skills.
After posting here 2 times and reading about 10 tutorials i am here with my last (?) question.
How would you detect if the snake is "biting" itself, i tried 2 things (which both failed totally)the latest one waschecking if there was any identical coordinates to the head.

package xyexs.snake.src;

import java.awt.BorderLayout;
import java.util.ArrayList;

import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;

public class Main {
	// Variables
	static int direction = 0;
	JFrame window = new JFrame(Reference.PROGRAM_NAME + " " + Reference.VERSION);
	static Panel panel = new Panel();
	static Score scoreboard = new Score();
	static int score = 0;
	public static ArrayList<Integer> chainX = new ArrayList<Integer>();
	public static ArrayList<Integer> chainY = new ArrayList<Integer>();
	static Boolean doGrow = false;

	// Main
	public static void main(String[] args) {
		chainX.add(0, 500);
		chainY.add(0, 350);
		chainX.add(0, 500);
		chainY.add(0, 300);
		chainX.add(0, 500);
		chainY.add(0, 250);
		JFrame window = new JFrame(Reference.PROGRAM_NAME + " " + Reference.VERSION);
		window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		window.setResizable(false);
		window.add(panel, BorderLayout.CENTER);
		window.add(scoreboard, BorderLayout.SOUTH);
		window.setSize(Reference.WINDOW_X, Reference.WINDOW_Y);
		window.pack();
		window.setVisible(true);
		int growCounter = 0;
		int moveCounter = 0;
		while (true) {
			try {
				Thread.sleep(Reference.TICK_TIME);
			}
			catch (InterruptedException e) {
				System.err.println("Sleep interrupted ( " + e + " )");
			}
			++growCounter;
			++moveCounter;
			if (growCounter == Reference.GROW_TICK) {
				growCounter = 0;
				doGrow = true;
			}

			if (moveCounter == Reference.MOVE_TICK) {
				Boolean isByTop = (chainY.get(0) == 0);
				Boolean isByBot = (chainY.get(0) + Reference.PIXEL_SIZE == Reference.WINDOW_Y);
				Boolean isByLeft = (chainX.get(0) == 0);
				Boolean isByRight = (chainX.get(0) + Reference.PIXEL_SIZE == Reference.WINDOW_X);
				Boolean facingSnake = false;
				for (int i = 1; i < chainX.size() ; i++) {
					if (chainX.get(0) == chainX.get(i) && chainY.get(0)== chainY.get(i)) {
						facingSnake = true;
						System.out.println("Dont bite yourself! Breaking");
						break;
					}
				}

				if (facingSnake == true) {
					break;

				}
				if (isByTop == true && direction == 0) {
					break;
				}
				else if (isByBot == true && direction == 2) {
					break;
				}
				else if (isByRight == true && direction == 1) {
					break;
				}
				else if (isByLeft == true && direction == 3) {
					break;
				}
				else {
					if (direction == 0) {
						chainX.add(0, chainX.get(0));
						chainY.add(0, chainY.get(0) - Reference.PIXEL_SIZE);
					}
					else if (direction == 1) {
						chainX.add(0, chainX.get(0) + Reference.PIXEL_SIZE);
						chainY.add(0, chainY.get(0));
					}
					else if (direction == 2) {
						chainX.add(0, chainX.get(0));
						chainY.add(0, chainY.get(0) + Reference.PIXEL_SIZE);
					}
					else if (direction == 3) {
						chainX.add(0, chainX.get(0) - Reference.PIXEL_SIZE);
						chainY.add(0, chainY.get(0));
					}
					if (doGrow == false) {
						chainY.remove(chainX.size() - 1);
						chainX.remove(chainX.size() - 1);
					}
					else {
						doGrow = false;
					}
					panel.repaint();
				}
				moveCounter = 0;
			}
			score = score + Reference.SCORE_INCREMENT;
			scoreboard.setText("Score: " + score);
		}

		ImageIcon image = new ImageIcon("\\C:\\Java\\Snake\\resources\\Lost.png");
		JLabel imageLabel = new JLabel();
		imageLabel.setIcon(image);
		imageLabel.setVisible(true);
		window.remove(panel);
		window.add(imageLabel, BorderLayout.CENTER);
		window.pack();
	}

	// Public Functions
	public static int getDir() {
		return direction;
	}

	public static void setDir(int dir) {
		direction = dir;
	}
}

This works sometimes but not close to always... help?
EDIT: never works..

[Xyexs]

bump

[Xyexs]

EDITED OUT:
i thought i solved it but i didn't.
It works sometimes, better than nothing...
latest attempt:

package xyexs.snake.src;

import java.awt.BorderLayout;
import java.util.ArrayList;

import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;

public class Main {
	// Variables
	static int direction = 0;
	JFrame window = new JFrame(Reference.PROGRAM_NAME + " " + Reference.VERSION);
	static Panel panel = new Panel();
	static Score scoreboard = new Score();
	static int score = 0;
	public static ArrayList<Integer> chainX = new ArrayList<Integer>();
	public static ArrayList<Integer> chainY = new ArrayList<Integer>();
	static Boolean doGrow = false;

	// Main
	public static void main(String[] args) {
		chainX.add(0, 500);
		chainY.add(0, 400);
		chainX.add(0, 500);
		chainY.add(0, 350);
		chainX.add(0, 500);
		chainY.add(0, 300);
		chainX.add(0, 500);
		chainY.add(0, 250);
		JFrame window = new JFrame(Reference.PROGRAM_NAME + " " + Reference.VERSION);
		window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		window.setResizable(false);
		window.add(panel, BorderLayout.CENTER);
		window.add(scoreboard, BorderLayout.SOUTH);
		window.setSize(Reference.WINDOW_X, Reference.WINDOW_Y);
		window.pack();
		window.setVisible(true);
		int growCounter = 0;
		int moveCounter = 0;
		while (true) {
			try {
				Thread.sleep(Reference.TICK_TIME);
			}
			catch (InterruptedException e) {
				System.err.println("Sleep interrupted ( " + e + " )");
			}
			++growCounter;
			++moveCounter;
			if (growCounter == Reference.GROW_TICK) {
				growCounter = 0;
				doGrow = true;
			}

			if (moveCounter == Reference.MOVE_TICK) {
				Boolean isByTop = (chainY.get(0) == 0);
				Boolean isByBot = (chainY.get(0) + Reference.PIXEL_SIZE == Reference.WINDOW_Y);
				Boolean isByLeft = (chainX.get(0) == 0);
				Boolean isByRight = (chainX.get(0) + Reference.PIXEL_SIZE == Reference.WINDOW_X);
				Boolean facingSnake = false;

				for (int i = 1; i < chainX.size(); i++) {
					if (direction == 0) {
						if (chainX.get(0) == chainX.get(i) && chainY.get(0) - Reference.PIXEL_SIZE == chainY.get(i)) {
							facingSnake = true;
							System.out.println("OUCH! You bit me! (facing north)");
							break;
						}
					}
					else if (direction == 1) {
						if (chainX.get(0) + Reference.PIXEL_SIZE == chainX.get(i) && chainY.get(0) == chainY.get(i)) {
							facingSnake = true;
							System.out.println("OUCH! You bit me! (facing east)");
							break;
						}
					}
					else if (direction == 2) {
						if (chainX.get(0) == chainX.get(i) && chainY.get(0) + Reference.PIXEL_SIZE == chainY.get(i)) {
							facingSnake = true;
							System.out.println("OUCH! You bit me! (facing south)");
							break;
						}
					}
					else if (direction == 3) {
						if (chainX.get(0) - Reference.PIXEL_SIZE == chainX.get(i) && chainY.get(0) == chainY.get(i)) {
							facingSnake = true;
							System.out.println("OUCH! You bit me! (facing west)");
							break;
						}
					}
				}
				if (facingSnake == true) {
					break;
				}
				if (isByTop == true && direction == 0) {
					break;
				}
				else if (isByBot == true && direction == 2) {
					break;
				}
				else if (isByRight == true && direction == 1) {
					break;
				}
				else if (isByLeft == true && direction == 3) {
					break;
				}
				else {
					if (direction == 0) {
						chainX.add(0, chainX.get(0));
						chainY.add(0, chainY.get(0) - Reference.PIXEL_SIZE);
					}
					else if (direction == 1) {
						chainX.add(0, chainX.get(0) + Reference.PIXEL_SIZE);
						chainY.add(0, chainY.get(0));
					}
					else if (direction == 2) {
						chainX.add(0, chainX.get(0));
						chainY.add(0, chainY.get(0) + Reference.PIXEL_SIZE);
					}
					else if (direction == 3) {
						chainX.add(0, chainX.get(0) - Reference.PIXEL_SIZE);
						chainY.add(0, chainY.get(0));
					}
					if (doGrow == false) {
						chainY.remove(chainX.size() - 1);
						chainX.remove(chainX.size() - 1);
					}
					else {
						doGrow = false;
					}
					panel.repaint();
				}
				moveCounter = 0;
			}
			score = score + Reference.SCORE_INCREMENT;
			scoreboard.setText("Made by Xyexs        Score: " + score+ "   Length: " + chainX.size());
		}

		ImageIcon image = new ImageIcon("\\C:\\Java\\Snake\\resources\\Lost.png");
		JLabel imageLabel = new JLabel();
		imageLabel.setIcon(image);
		imageLabel.setVisible(true);
		window.remove(panel);
		window.add(imageLabel, BorderLayout.CENTER);
		window.pack();
	}

	// Public Functions
	public static int getDir() {
		return direction;
	}

	public static void setDir(int dir) {
		direction = dir;
	}
}

[jim829]

Have you tried deriving line segments from the points that make up the snake and seeing when the
line segments intersect with other line segments. See Line2D (Java Platform SE 7 )

Regards,
Jim

[Xyexs]

I didn't understand a word :P

[jim829]

Well, I am not certain how your snake is constructed so I will pretend it is a series of coordinates that slither around. Let's say the head starts at (x1,y1), the next section at (x2,y2), then (x3, y3), and (x4.y4). If you want to see if the segment of the snake (x1,y1,x2,y2) crosses some other segment (say x45,y45,x46,y46) then if the two segments cross each other (intersect) then the snake crossed itself. There is a method in the link I provided earlier which has methods to detect the intersection of two line segments.

Regards,
Jim

[Xyexs]

It's based off 2 arraylists (chainX and chainY) that contain them like {50,100,150 (pixel_size is 50, its kind of a "part" of the snake)} and {200,200,200}

id did this:

for (int i = 1; i < chainX.size(); i++) {
	if (direction == 0) {
		if (chainX.get(0) == chainX.get(i) && chainY.get(0) - Reference.PIXEL_SIZE == chainY.get(i)) {
			facingSnake = true;
	   	        System.out.println("OUCH! You bit me! (facing north)");
			Break;
		}
	}
	else if (direction == 1) {
	     if (chainX.get(0) + Reference.PIXEL_SIZE == chainX.get(i) && chainY.get(0) == chainY.get(i)) {
                facingSnake = true;
		System.out.println("OUCH! You bit me! (facing east)");
		break;
	     }
	}
	else if (direction == 2) {
		if (chainX.get(0) == chainX.get(i) && chainY.get(0) + Reference.PIXEL_SIZE == chainY.get(i)) {
			FacingSnake = true;
			System.out.println("OUCH! You bit me! (facing south)");
			break;
		}
	}
	else if (direction == 3) {
		if (chainX.get(0) - Reference.PIXEL_SIZE == chainX.get(i) && chainY.get(0) == chainY.get(i)) {
		        facingSnake = true;
		        System.out.println("OUCH! You bit me! (facing west)");
			break;
		}
	}
}

Well, im to tired to do this now... it's 2 pm here... :P

[JosAH]

If you had used Points for the coordinates of the snake segments, a snake would look like this:

List<Point> snake= ...;

Assuming the head of the snake is at position #0, your check reduces to just this:

if (snake.lastIndexOf(snake.get(0)) > 0)
   // snake has bitten itself.

kind regards,

Jos