For additional java game programming projects with sample code provided, go to: www.krohneducat... Explanation of how to create the game "Snake" as a Java Applet.
I understand all the syntax and pretty much everything except the try - catch portion. I haven't really studied threads or exceptions so that's my fault. Good video!
I don't have any option to run the SnakeGame file? I followed step by step up until the point you created the Snake class, but I don't want to move on cause I can't even run the Snakegame file, does it have something to do with Applet being deprecated?
It says I have an error when I run it. Can you please explain to me if you can. Basically my snake won't move at all and sends this error message: "Exception in thread "Thread-1" java.lang.NullPointerException at SnakeGame.run(SnakeGame.java:58) at java.lang.Thread.run(Thread.java:748)" Please help!
When typing public void draw(Graphics g){ g.setColor(Color.white); for(Point p : snakePoints); g.fillRect(p.getX(), p.getY(), 4, 4); I get a error saying p needs its own variable.. idk what to do p is underlined red /
only one of the rectangles of the snake is being drawn, not sure why, but when i move it, it moves diagonally and then i can see the other square blocks
The line "List snakePoint;" keeps giving me an error. It keeps saying "The type List is not generic; it cannot be parameterized with arguments ." I have double and triple checked that my syntax is the same as yours. Can you please help?
Now I have another problem.. it moves perfectly, but when I run ver the token it works the first 1 or few times but then after I run over it and it doesn't work anymore :( please oeone help
uhh... I did everything on the part where we were actually working towards MOVING the snake but when I run it it and i press up, the snake just shrinks :( My Code in Snake.java: package snake; import java.awt.Color; import java.awt.Graphics; import java.util.ArrayList; import java.util.List; public class Snake { List snakePoints; int xDir, yDir; boolean isMoving, elongate; final int STARTSIZE = 20, STARTX = 150, STARTY = 150;
public Snake(){ snakePoints = new ArrayList(); xDir = 0; yDir = 0; isMoving = false; elongate = false; snakePoints.add(new Point(STARTX, STARTY)); for(int i = 1; i < STARTSIZE; i++){ snakePoints.add(new Point(STARTX - i * 4, STARTY)); }
} public boolean isMoving(){ return isMoving; } public void setIsMoving(boolean b){ isMoving = b; } public void draw(Graphics g){ g.setColor(Color.white); for(Point p : snakePoints){ g.fillRect(p.getX(), p.getY(), 4, 4); } } public void move(){ if(isMoving){ Point temp = snakePoints .get(0); Point last = snakePoints.get(snakePoints.size() - 1); Point newStart = new Point(temp.getX() + xDir * 4, temp.getY() + yDir * 4); for(int i = snakePoints.size() - 1; i >= 1; i--){ snakePoints.set(i, snakePoints.get(i - 1)); } snakePoints.set(0, newStart); }
} public int getXDir(){ return xDir; } public int getYDir(){ return yDir; } public void setXDir(){ xDir = xDir; } public void setYDir(){ yDir = yDir; } //X position of head of snake public int getX(){ return snakePoints.get(0).getX(); } //Y position of head of snake public int getY(){ return snakePoints.get(0).getX(); }
} My code in SnakeGame.java: package snake; import java.applet.Applet; import java.awt.Color; import java.awt.Graphics; import java.awt.Image; import java.awt.event.KeyEvent; import java.awt.event.KeyListener; public class SnakeGame extends Applet implements Runnable, KeyListener{ Graphics gfx; Image img; Thread thread; Snake snake; public void init(){ this.resize(400, 400); img = createImage(400, 400); gfx = img.getGraphics(); this.addKeyListener(this); snake = new Snake(); thread = new Thread(this); thread.start(); } public void paint(Graphics g){ gfx.setColor(Color.black); gfx.fillRect(0, 0, 400, 400); snake.draw(gfx);
g.drawImage(img, 0, 0, null); } public void update(Graphics g){ paint(g); } public void repaint(Graphics g){ paint(g); } public void run() { for(;;){
+MarcLefer Highlight the lines that you want to move. Then, hold down Alt and press Up or Down. You can do this with single lines as well as several highlighted lines.
When I do the snakePoints.set(0,newStart); it gives me an error telling me to just remove it. When i do the.getY and .getX it for some reason is a double. Does anyone know why this it?
public class Snake { List snakePoints; int xDir, yDir; public Snake(){ snakePoints = new ArrayList(); } keeps saying there is an error saying that the list dont take paramerters
Every time i press restart in the applet after the game is over, my snake gets faster. After the next restart it gets even more faster. If i close the Applet completly and start it completly new, it will start at his default speed. Does anyone have an idea ? :/
Hey guys this a Thread problem. It is adding the delay to itself everytime. I added a "Hit R for Reload" string after the game under score then do this in keyPressed: if(gameOver){ if(e.getKeyCode() == KeyEvent.VK_R){ reload(); } } then make a reload function that reloads and stops the thread Fixed: public void reload(){ this.destroy(); this.init(); thread.stop(); }
bro, i am not getting the placement of your Key Listener it is placed in init() which in executed only fiirst time by compiler how it listen to Keyaction all time with thread please explain
Applets do not have a "main" method the way that typical Java programs do. Specific methods are initiated by a web browser. I would say that the closest thing to a "main" method in an Applet would be "init". When an applet is placed in a web browser, the "init" method is called first, followed by "start", and then "paint".
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I cant thank you enough I learned so much from this tutorial and everything was explained so well great job :)
Picture by picture explanation of run function is fantastic
I understand all the syntax and pretty much everything except the try - catch portion. I haven't really studied threads or exceptions so that's my fault. Good video!
Thanks for the great videos. They've definitely helped me take the next step in programming.
*Stops recording* "MOM TURN OFF THE HAIR DRYER!!!" *Starts recording again* 13:22
lol. Was my fiance, but close.
+Krohn - Education 👍🏽 Good tutorial btw.
Krohn - Education what is your keyboard's brand i liked its sound :D
Hey, just saying, you can use ctrl + shift + o to import instead of clicking it and yeah..
Great vid btw!
+MarcLefer Thanks for sharing that shortcut. Definitely a good time saver.
+Krohn - Education np :)
what are the differences between JPanel and Applet, is it better to choose Applet for games?
Where is the KeyReleased part? Is that needed or not?
Awesome tutorial
I don't have any option to run the SnakeGame file? I followed step by step up until the point you created the Snake class, but I don't want to move on cause I can't even run the Snakegame file, does it have something to do with Applet being deprecated?
Did you ever figure out it out
Great Vid! Can you atleast tell how to restart the game by pressing SPACE or ESC?
It says I have an error when I run it. Can you please explain to me if you can. Basically my snake won't move at all and sends this error message:
"Exception in thread "Thread-1" java.lang.NullPointerException
at SnakeGame.run(SnakeGame.java:58)
at java.lang.Thread.run(Thread.java:748)"
Please help!
when I am trying to import java.applet.Applet it is sowing error that the type applet is deprecated..How to resolve this??
Applet is deprecated in java 9.
@David Assio use JPanel
Applet is deprecated since Java 9. Use Java 8 instead.
i have a question do you control the snake when you run it or does it run on its own
When typing
public void draw(Graphics g){
g.setColor(Color.white);
for(Point p : snakePoints);
g.fillRect(p.getX(), p.getY(), 4, 4);
I get a error saying p needs its own variable..
idk what to do p is underlined red /
Can you help me? Why my snake after i run , it still get long? Not get normal when i run before done
I am getting error at
img=createImage(400,400);
createImage can't be resolved to a type.. Please help me every other thing is error free for me..
only one of the rectangles of the snake is being drawn, not sure why, but when i move it, it moves diagonally and then i can see the other square blocks
nevermind, im just a goofball lmaoo
Why would you add a repaint() function if you just can call this.paint() again?
The line "List snakePoint;" keeps giving me an error. It keeps saying "The type List is not generic; it cannot be parameterized with arguments ." I have double and triple checked that my syntax is the same as yours. Can you please help?
Er, never mind. Eclipse decided to automatically import java.awt.List instead of java.util.List
please text the code ready, very necessary
Mine keeps flickering between black and white. Why is this?
Now I have another problem.. it moves perfectly, but when I run ver the token it works the first 1 or few times but then after I run over it and it doesn't work anymore :( please oeone help
Same problem here
maybe a problem in your game loop
uhh... I did everything on the part where we were actually working towards MOVING the snake but when I run it it and i press up, the snake just shrinks :(
My Code in Snake.java:
package snake;
import java.awt.Color;
import java.awt.Graphics;
import java.util.ArrayList;
import java.util.List;
public class Snake {
List snakePoints;
int xDir, yDir;
boolean isMoving, elongate;
final int STARTSIZE = 20, STARTX = 150, STARTY = 150;
public Snake(){
snakePoints = new ArrayList();
xDir = 0;
yDir = 0;
isMoving = false;
elongate = false;
snakePoints.add(new Point(STARTX, STARTY));
for(int i = 1; i < STARTSIZE; i++){
snakePoints.add(new Point(STARTX - i * 4, STARTY));
}
}
public boolean isMoving(){
return isMoving;
}
public void setIsMoving(boolean b){
isMoving = b;
}
public void draw(Graphics g){
g.setColor(Color.white);
for(Point p : snakePoints){
g.fillRect(p.getX(), p.getY(), 4, 4);
}
}
public void move(){
if(isMoving){
Point temp = snakePoints .get(0);
Point last = snakePoints.get(snakePoints.size() - 1);
Point newStart = new Point(temp.getX() + xDir * 4, temp.getY() + yDir * 4);
for(int i = snakePoints.size() - 1; i >= 1; i--){
snakePoints.set(i, snakePoints.get(i - 1));
}
snakePoints.set(0, newStart);
}
}
public int getXDir(){
return xDir;
}
public int getYDir(){
return yDir;
}
public void setXDir(){
xDir = xDir;
}
public void setYDir(){
yDir = yDir;
}
//X position of head of snake
public int getX(){
return snakePoints.get(0).getX();
}
//Y position of head of snake
public int getY(){
return snakePoints.get(0).getX();
}
}
My code in SnakeGame.java:
package snake;
import java.applet.Applet;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
public class SnakeGame extends Applet implements Runnable, KeyListener{
Graphics gfx;
Image img;
Thread thread;
Snake snake;
public void init(){
this.resize(400, 400);
img = createImage(400, 400);
gfx = img.getGraphics();
this.addKeyListener(this);
snake = new Snake();
thread = new Thread(this);
thread.start();
}
public void paint(Graphics g){
gfx.setColor(Color.black);
gfx.fillRect(0, 0, 400, 400);
snake.draw(gfx);
g.drawImage(img, 0, 0, null);
}
public void update(Graphics g){
paint(g);
}
public void repaint(Graphics g){
paint(g);
}
public void run() {
for(;;){
snake.move();
this.repaint();
try {
Thread.sleep(40);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public void keyPressed(KeyEvent e) {
if(!snake.isMoving()){
if(e.getKeyCode() == KeyEvent.VK_UP || e.getKeyCode() == KeyEvent.VK_RIGHT ||
e.getKeyCode() == KeyEvent.VK_DOWN){
snake.setIsMoving(true);
}
}
if(e.getKeyCode() == KeyEvent.VK_UP){
if(snake.getYDir() != 1){
snake.setYDir();
snake.setXDir();
}
}
if(e.getKeyCode() == KeyEvent.VK_DOWN){
if(snake.getYDir() != -1){
snake.setYDir();
snake.setXDir();
}
}
if(e.getKeyCode() == KeyEvent.VK_LEFT){
if(snake.getXDir() != 1){
snake.setXDir();
snake.setYDir();
}
}
if(e.getKeyCode() == KeyEvent.VK_RIGHT){
if(snake.getXDir() != -1){
snake.setXDir();
snake.setYDir();
}
}
}
public void keyReleased(KeyEvent arg0) {
// TODO Auto-generated method stub
}
public void keyTyped(KeyEvent arg0) {
// TODO Auto-generated method stub
}
}
+MarcLefer actually im going to delete everything and rewrite the code :I
have u used a data structure for the coding part???
Please be more specific.
24:18 how did you move all that like that
+MarcLefer Highlight the lines that you want to move. Then, hold down Alt and press Up or Down. You can do this with single lines as well as several highlighted lines.
+Krohn - Education thanks!
Plz give code of this game
Alright so I re-coded it and it moves! But.. when I press the Left arrow key it moves right and vice versa.. Not sure what I did wrong.
+MarcLefer nvm fxed it
can you send the code
Mine keeps saying that there is no main method
how would you change the speed of the snake?
He shows how to do this at the end of the video, by modifying the 'sleep' time period in the run() method
Hi, do you have other java applet codes for me?
Check out: th-cam.com/video/xIqeK2hzx1I/w-d-xo.html
my snake pops up in the top left corner and only as one pixel can anyone help?
How did he make it run without a main. I tried doing this on netbeans, but it said no main found.
In this video he uses a java applet. Java applets do not need a main method.
When I do the snakePoints.set(0,newStart); it gives me an error telling me to just remove it.
When i do the.getY and .getX it for some reason is a double. Does anyone know why this it?
I also have to cast the getY and X as an int which i think might be screwing something up to
public class Snake {
List snakePoints;
int xDir, yDir;
public Snake(){
snakePoints = new ArrayList();
}
keeps saying there is an error
saying that the list dont take paramerters
me too :/
u have to import the list of util pacakge not the list of applet package
my snake is dies randomly please rply me...
superbbbbbbbb
nice
Every time i press restart in the applet after the game is over, my snake gets faster. After the next restart it gets even more faster. If i close the Applet completly and start it completly new, it will start at his default speed.
Does anyone have an idea ? :/
I had that same problem. You just have to close it and rerun the program.
Hey guys this a Thread problem. It is adding the delay to itself everytime. I added a "Hit R for Reload" string after the game under score then do this in keyPressed:
if(gameOver){
if(e.getKeyCode() == KeyEvent.VK_R){
reload();
}
}
then make a reload function that reloads and stops the thread Fixed:
public void reload(){
this.destroy();
this.init();
thread.stop();
}
@@TenMinuteTraditionalLax it doesn't work for me perhaps u have other solution?
How do i make Jar file
bro, i am not getting the placement of your Key Listener
it is placed in init()
which in executed only fiirst time by compiler how it listen to Keyaction all time with thread please explain
How to make this an application? (not an applet)
Search on how to make it executable .exe
How to study all this stuff?
Express specific book plzz
my snake is not moving and I dont know why u.u
Where is your main method?
Applets do not have a "main" method the way that typical Java programs do. Specific methods are initiated by a web browser. I would say that the closest thing to a "main" method in an Applet would be "init". When an applet is placed in a web browser, the "init" method is called first, followed by "start", and then "paint".
Snake is not moving please help I did everything up to 27:42
Check your keyPressed event. Make sure you don't have VK_KP_LEFT instead of VK_LEFT, I had the same problem
@@hernanadrielmartinezmazari676 thank you very much ill check today in class and get back to you
@@hernanadrielmartinezmazari676 okay after looking at it with my teacher my keyListener method isnt even running
16:08 - I stayed there
20:17
21:06
go to: 16:54
My snake dies randomly
I dnt understand
Can u Upload the Source?
too fast
but good
If you go to settings, you can slow the video down to 0.75x or 0.5x speed.
11:21
No clue what to do
I haven't learn anything. It's way too fast.
Don't stick with the details, just try to understand the concept. Next time everything makes more sense.