Nils Anton

I took both your suggestion and used the rectangle class. I've also created a custom class, Card, that extends the imageIcon-class. When a Card is created a rectangle is also created, so when I click on a rectangle I can check which Card it's part of - and then flip that Card; change its imageIcon.

Thanks again for the help .

For those curious, here's my code:

CODE LINK:
https://www.dropbox.com/sh/9m5n64vqmmw5o8w/AACl_h1eO6seW42TULZ-jZGha?dl=0

CODE - ImageLump-class (WiP name):
import java.awt.*; import javax.swing.*; import java.awt.event.*; import java.util.ArrayList; public class ImageLump extends JPanel { ArrayList<Card> cardList = new ArrayList<Card>(); public ImageLump() { Card mimic = new Card("/images/mimic.jpg", 100, 100); Card mushroomMan = new Card("/images/mushroomMan.jpg", 500, 200); Card frampf = new Card("/images/frampf.jpg", 600, 300); cardList.add(mimic); cardList.add(mushroomMan); cardList.add(frampf); addMouseListener(new MouseAdapter(){ public void mousePressed(MouseEvent e) { int x = e.getX(); int y = e.getY(); Card clickedCard = rectangleClicked(x, y); // get card rectangle is part of if (clickedCard != null) { // if there's a rectangle at the position clickedCard.flip(); // flip card repaint(); // repaint panel } } }); } /* Check rectangles. */ public Card rectangleClicked(int x, int y) { Card card = null; for (int i = 0; i < cardList.size(); i++) { if (cardList.get(i).getRectangle().contains(x, y)) { card = cardList.get(i); break; } } return card; } /* Paints icon. */ public void paintComponent(Graphics g) { super.paintComponent(g); for (int i = 0; i < cardList.size(); i++) { cardList.get(i).getIcon().paintIcon(this, g, cardList.get(i).getXPosition(), cardList.get(i).getYPosition()); } } /* Create frame and panel. */ public static void main (String args[]) { ImageLump gui = new ImageLump(); JFrame frame = new JFrame("Image Pile (frame)"); frame.setSize(1024, 768); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.getContentPane().add(BorderLayout.CENTER, gui); frame.setVisible(true); gui.setOpaque(true); gui.setBackground(Color.WHITE); gui.setLayout(null); } }

CODE - Card-class:
import javax.swing.*; import java.awt.*; public class Card extends ImageIcon { private int xPosition; private int yPosition; private String currentImageAddress; private String fileAddress; private String cardRearAddress = "/images/cardRear.jpg"; ImageIcon icon; Rectangle rectangle; boolean displayFront = true; /* Constructor. */ public Card(String fileAddress, int xPosition, int yPosition) { this.fileAddress = fileAddress; this.xPosition = xPosition; this.yPosition = yPosition; currentImageAddress = fileAddress; loadImage(); rectangle = new Rectangle(xPosition, yPosition, icon.getIconWidth(), icon.getIconHeight()); } public int getXPosition() { return xPosition; } public int getYPosition() { return yPosition; } /* Flip card. */ public void flip() { if (displayFront) { displayFront = false; currentImageAddress = cardRearAddress; } else { displayFront = true; currentImageAddress = fileAddress; } loadImage(); } /* Get icon. */ public ImageIcon getIcon() { return icon; } /* Get rectangle. */ public Rectangle getRectangle() { return rectangle; } /* Load image. */ public void loadImage() { icon = new ImageIcon(getClass().getResource(currentImageAddress)); } /* Demonstrate and test class. */ public static void main (String args[]) {} }

IMAGE EXAMPLES:

Thank you Piet for the further help .

Thank you Carey .

Hello!

Full disclosure: this problem is part of an exercise - so I'm only looking for tips & suggestions - yet I'm completely stuck, so I feel the need to ask for help.

I'm trying to create a window that displays images. You can turn over the images by clicking on them, and move them by holding them.

I wanted to use JFrame, JPanel, JLabels, and ImageIcons to solve the task, yet I'm now allowed to use JLabels - so I've attempted to use a paintComponent instead.

I currently got a JFrame, with a JPanel, and an image drawn on the JPanel. I've also been able add a MouseAdapter to the JPanel that gets the coordinates of the area being pressed. Yet I don't know how to use it to select my ImageIcon - maybe save the JPanel area the ImageIcon occupies, so I can check the mouse coordinates against it? - or something else?

Your help is highly appreciated!

/Cheers

CODE LINK:
https://www.dropbox.com/sh/9m5n64vqmmw5o8w/AACl_h1eO6seW42TULZ-jZGha?dl=0

CODE:
import java.awt.*; import javax.swing.*; import java.awt.event.*; public class ImageHeap extends JPanel { ImageIcon icon = new ImageIcon(this.getClass().getResource("/images/mushroomMan.jpg")); // load image public ImageHeap() { addMouseListener(new MouseAdapter(){ public void mousePressed(MouseEvent e) { // print coordinates of plane area that is clicked int x = e.getX(); int y = e.getY(); System.out.println(x + " , " + y); } }); } /* Paints icon. */ public void paintComponent(Graphics g) { super.paintComponent(g); ImageIcon icon = new ImageIcon(this.getClass().getResource("/images/mushroomMan.jpg")); icon.paintIcon(this, g, 512, 384); } /* Create frame and panel. */ public static void main (String args[]) { ImageHeap gui = new ImageHeap(); JFrame frame = new JFrame("Image Pile (frame)"); frame.setSize(1024, 768); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.getContentPane().add(BorderLayout.CENTER, gui); frame.setVisible(true); gui.setOpaque(true); gui.setBackground(Color.WHITE); gui.setLayout(null); } }

IMAGE EXAMPLE:

Hmmm. Really?

NIM is one of the oldest computer games there is, and the reason is that it has a very simple winning strategy.

In fact, I remember going to an exhibition at Kensington Olympia when I was about 7 (which would have been 1964) and getting 30 seconds of fame on national TV because I worked out how to "beat the computer" at a NIM game with either 13 or 15 matchsticks on the bottom row.

So you might want to look up the way to win rather than just having the computer take sticks at random.

It's time for me to do some investigation .

All the formatting tips are great - they make sense - so I'll be sure to use them in the future .

That's fine. Just remember this: Your methods should do one thing and only one thing well. If it's calculating things, avoid mixing in input and/or display. If it's display, avoid mixing in lots of calculations and/or input. Those things that you want to mix in, that's what return values and parameters are for. So, main calls a method to get user input, then passes the input on the method that does calculations, then passes the results to another method that displays them.

I like this way of thinking, since it makes it easier to decide what a method should contain.

Note that a constructor should never call any public or protected methods that are not specified as "final". If any subclass of your Player class happens to override that non-final method you will encounter problems that are very difficult to debug.

I'll try to keep this in mind.


Thank you all for the help .

@Winston Gutkowski: thank you for the welcome .

However, while I see a HumanPlayer, I don't see any ComputerPlayer class. What are the differences between them?
Try to explain it to us IN ENGLISH, not in "Java-speak".

The human has to pick at least 1 stick, and can pick up to half of the sticks left - rounded down, i.e. if there's 21 sticks left she can take 10 sticks.

The computer randomly takes a number of sticks - while following the above rules.

Note that this is NOT the game itself, simply the "playing area"; and many games - including Chess, Go, Connect4/5, Mastermind, etc - have one. It's also the thing that you're likely to want to display (however you do that).

Sounds like a fun thing to add - I haven't done any "graphics" yet - yet I'm sure there's good guides on the net for how to do it .

Also: DON'T include underscores ('_') in your variable names. It's regarded as "Python-esque", and generally frowned on in the Java community. You can find proper naming conventions here; and I advise you to memorise them as quickly as possible.

I'll stay away from the underscores, and I've already bookmarked the link : ).


@Junily Lacar: loads of great feedback

One unnecessarily short name: playerNr_ (it does sound stupid when I read it out loud ), one unnecessarily long: playerNumber, playerName, etc.

I've got no excuse for the lines:
playerArray_[0] = p1_; playerArray_[1] = p2_;

I'll be sure to stay away from underscore naming.

Overall, this code strongly hints at someone who has experience writing programs in another language. I doubt this is your first rodeo, right Cowboy?

I've before played around some in C#, UnityScript, Python, and done some visual scripting in Kismet and Hammer. Yet I recently started studying programming at school, so I feel I don't quite get what:

In a program this small, mixing concerns is not much of a big deal. In larger programs, however, you should think about separation of concerns, particularly the concerns of doing calculations vs input/display.

Using inheritance and polymorphism to simplify the decision to prompt or not prompt for input works in this case but experienced hands will detect a slight smell there and will keep a wary eye on it. Mixed responsibilities tend to make for code that is more difficult to maintain.

As for using interfaces vs abstract classes, my rule of thumb is to use an interface when you know there will be a definite need to have an unknown number of different implementations. Also, when the idea represented is along or crosses application layer boundaries (View, Control, Data, Service, Model, etc.), prefer interfaces as they have the least amount of coupling.

Yet I appreciate your attempt to explain it to me : ).

2 seconds is an awfully long time to simulate a computer trying to make a decision. Are you trying to make the computer look stupid or what? ;)

I wouldn't want to look stupid when I'm playing against it ;).


Thank you both for taking time out of your Friday to help me! : ).

Hello!

As a school exercise I've created a Nim game. The exercise is supposed to teach me about abstract classes, inheritance, and interfaces. Therefore I decided to have an abstract Player-class that the human and computer player inherit methods and instance variables from.

I would love to get some feedback on the code - especially the Player-, HumanPlayer-, and ComputerPlayer-class.

Also, I think that I understand abstract classes, and inheritance - yet I don't think I understand interfaces - more than that they're abstract classes. I've read some articles about them, yet I still don't feel that I know when to use an interface. Could you help me by giving me an example of when you should use an interface?

And answering this question as well: when initializing a variable in a constructor, is it better to have the constructor call a set-method, i.e.:
public Player(int playerNr, String playerRace) { setPlayerNr(playerNr); }

or have the constructor initialize the variables:
playerNr_ = playerNr;
?


Link to java files:
https://www.dropbox.com/sh/9m5n64vqmmw5o8w/AACl_h1eO6seW42TULZ-jZGha?dl=0

"GameTestDrive.java" is used to run the game.

Your help is appreciated .

CODE:
import java.util.Random; // for randomizing nr of sticks computer takes /* * ComputerPlayer is subclass of Player-class. */ public class ComputerPlayer extends Player { // use superclass constructor public ComputerPlayer(int playerNr, String playerRace) { super(playerNr, playerRace); } /* * Computer player randomly takes an allowed amount of sticks. */ public int takeSticks(int sticksLeft) { Random myRandom = new Random(); int nSticks = myRandom.nextInt(sticksLeft / 2) + 1; try { Thread.sleep(2000L); // pause so player easier can see what computer does } catch (Exception e) {} System.out.println(this + " takes " + nSticks + " stick(s)."); return nSticks; } }

public class Game { private Player[] playerArray_ = new Player[2]; private Player p1_; private Player p2_; private Player currentPlayer_; private int sticks_ = 20; /* * Player chooses gametype. */ public Game() { GetInputFromUser scanner = new GetInputFromUser(); System.out.println("Welcome to NIM!" + "\n" + "Enter a number to choose gametype" + "\n" + "(0) two human players" + "\n" + "(1) one human- and one computer player" + "\n" + "(2) two computer players"); int gameType = scanner.getInput(); while (gameType < 0 || // some error handling; int needs to be [0, 2] gameType > 2) { gameType = scanner.getInput(); } setPlayers(gameType); } /* * Set players as humans or computers. */ private void setPlayers(int gameType) { playerArray_[0] = p1_; playerArray_[1] = p2_; if (gameType == 0) { playerArray_[0] = new HumanPlayer(1, "Human"); playerArray_[1] = new HumanPlayer(2, "Human"); }else if (gameType == 1) { playerArray_[0] = new HumanPlayer(1, "Human"); playerArray_[1] = new ComputerPlayer(2, "Computer"); } else { playerArray_[0] = new ComputerPlayer(1, "Computer"); playerArray_[1] = new ComputerPlayer(2, "Computer"); } // list what players has what number, and if they're a human or computer System.out.println(playerArray_[0] + " - " + playerArray_[0].getPlayerRace() + "\n" + / playerArray_[1] + " - " + playerArray_[1].getPlayerRace() + "\n"); } /* * Start a session - a session consists of turns. */ public String playSession(){ printSticksLeft(); while (sticks_ != 1) { for (Player p : playerArray_) { currentPlayer_ = p; // keep track of current player to assign winner setSticks(playTurn()); // a player takes a turn printSticksLeft(); if(getSticks() == 1) { // if only 1 stick is left: assign winner break; } System.out.println(); } } return "\n" + "The winner is: " + (currentPlayer_) + "!"; } /* * Each player takes one turn each. */ public int playTurn() { System.out.println(currentPlayer_ + "'s turn."); return currentPlayer_.takeSticks(getSticks()); } public void printSticksLeft() { System.out.println("Remaining sticks: " + sticks_); } /* * Remove taken sticks (nSticks) from total sticks (sticks_). */ public void setSticks(int nSticks) { sticks_ = sticks_ - nSticks; } public int getSticks() { return sticks_; } }

/* * Used for starting game. */ public class GameTestDrive { public static void main (String[] args) { Game gameSession = new Game(); // start game session System.out.println(gameSession.playSession()); // print result of game session } }

/* * Class used to get player input. */ import java.util.Scanner; public class GetInputFromUser { public int getInput(){ Scanner input = new Scanner(System.in); int userInput = input.nextInt(); return userInput; } }

/* * HumanPlayer is subclass of Player-class. */ public class HumanPlayer extends Player { // use superclass constructor public HumanPlayer(int playerNr, String playerRace) { super(playerNr, playerRace); } /* * Player is forced to take an allowed amount of sticks. */ public int takeSticks(int sticksLeft) { GetInputFromUser scanner = new GetInputFromUser(); System.out.println("How many sticks do you take?"); int nSticks = scanner.getInput(); while (nSticks < 1 || nSticks > (sticksLeft/2)) { System.out.println("Illegal move! - try again!"); nSticks = scanner.getInput(); } return nSticks; } }

public abstract class Player { private int playerNr_; private String playerRace_; public Player(int playerNr, String playerRace) { setPlayerNr(playerNr); setPlayerRace(playerRace); } /* * Human and computer has different takeSticks-methods - so they're defined in respective subclass. */ public abstract int takeSticks(int sticksLeft); public int getPlayerNr() { return playerNr_; } public String getPlayerRace() { return playerRace_; } public void setPlayerRace(String playerRace) { playerRace_ = playerRace; } public void setPlayerNr(int playerNr) { playerNr_ = playerNr; } public String toString() { return "Player " + playerNr_; } }

Thank you for the extensive help!

@Dave: I think it displays what the Dice rolled - so in this case 2.

@Henry: local variables don't get default values. Instance variables get default values. If they're created at the same time - would the instance variable then overwrite the local variabel?

I just also found another error in the code: the "nsides" variabel in PairOfDice should be "nSides".

Also, thanks for the welcome .

Hello!

The task I'm attempting to solve is part of a school assignment. I've already solved it one way - yet that solution is rather ugly - so I'm attempting to solve it another way.

The task requires me to create a new class PairOfDice that creates two Dice objects, rolls them, checks if they're a pair, and then writes the result. I'm trying to have the PairOfDice class create two Dice classes that roll themselves, save their value to themselves, and I then have the PairOfDice class check if they rolled a pair, and lastly write out the result. Yet when I attempt to have the PairOfDice class create two Dice objects, they are created with a wrong number of sides (value), yet I don't understand why.

I've attempted to search this forum, and the Internet, yet I still don't understand what the error is - would you please help me?

Dice class:
public class Dice { private int nSides; private int value; public Dice() { this(6); } public Dice(int nSides) { if (nSides<2) { System.out.println("Wrong number of sides"); this.nSides = 6; } else { this.nSides = nSides; } this.roll(); } public int getValue() { return this.value; } public void roll() { this.value = (int)(Math.random()*this.nSides) + 1; } public String toString() { return "Dice(" + this.nSides + ", " + this.value + ")"; } }

PairOfDice class:
public class PairOfDice { private int nsides; Dice dice01; Dice dice02; private int[] arrayValues = new int[2]; public PairOfDice() { this(6); } public PairOfDice(int nSides) { Dice dice01 = new Dice(nsides); Dice dice02 = new Dice(nsides); } public int[] getValues() { this.arrayValues[0] = this.dice01.getValue(); this.arrayValues[1] = this.dice02.getValue(); return arrayValues; } public boolean isPair() { if (this.arrayValues[0] == this.arrayValues[1]) { return true; } else { return false; } } public String toString() { return dice01.toString() + dice02.toString(); } }

PairOfDiceTestRun class:
public class PairOfDiceTestRun { boolean isPair = false; public static void main (String[] args) { PairOfDice pairOfDice = new PairOfDice(); if (pairOfDice.isPair() == true) { System.out.print(pairOfDice.toString() + "\t Pair!"); } else { System.out.print(pairOfDice.toString()); } } }


/Regards,
Nils

EDIT: I've done some debugging - when I run:
Dice dice01 = new Dice(nsides);

dice01 gets the value:
dice01 Dice(6, 2) Dice

which I assume has something to do with toString - does it automatically rewrite dice01's value when it's created?