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How would i pass an object to a Javafx class in order to procedurally create the GUI?

So I've been looking around and couldn't find an answer that matches my question. Apologies if this question has been answered.
Here are my two classes:
Game Class
package sample;
import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.layout.VBox;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;
import java.awt.*;
public class Game extends Application{
Player Player;
Map Map;
#Override
public void start(Stage primaryStage) throws Exception {
primaryStage.setTitle("Game");
Group root = new Group();
double x =0;
double y = 0;
for (Tile[] out: Map.Tiles_Array) {
for (Tile in : out) {
Rectangle rectangle = new Rectangle();
rectangle.setHeight(10);
rectangle.setWidth(10);
rectangle.setX(x);
rectangle.setY(y);
root.getChildren().add(rectangle);
x = x + 10;
}
y = y+ 10;
x = 0;
}
VBox box = new VBox();
root.getChildren().add(box);
final Scene scene = new Scene(root);
scene.setFill(null);
primaryStage.setFullScreen(true);
primaryStage.setScene(scene);
primaryStage.show();
}
public Game(Map map , Player player) {
Map= map;
Player = player;
}
public static void main(String[] args) {
launch(args);
}
void update(){
}
}
`` MainMenu class
package sample;
import javafx.stage.Stage;
import java.util.Scanner;
public class MainMenu {
public static void main(String[] args) {
Print("***************************************************");
Print("* Welcome to the best Object Orientated game ever *");
Print("***************************************************");
Print("What is your Name?");
var Name = User_Input();
Print("Are you Male Or Female (M/F)");
char Gender = Check_Gender(User_Input().charAt(0));
Print("Whats is your age");
int Age = Exception_Catcher();
Print("Great, Now you need to choose your avatar that you will play with......");
Print("Your choice is between Archer(A), Knight(K) or Wizard(W)");
Characters Chosen_Character = Check_Choice(User_Input().charAt(0));
Print(Name + " " + Gender +" "+ Age + " " + Chosen_Character.Name); // debugging
Player player1 = new Player(Name,Age,Gender,Chosen_Character);
var Map = new Map(25,25 , player1);
Game My_Game = new Game(Map,player1);
}
private static void Print(String input){ // Prints string it is given
System.out.println(input);
}
private static String User_Input(){ // returns Users response
Scanner s = new Scanner(System.in);
return s.nextLine();
}
private static char Check_Gender(char Letter){
Letter = Character.toUpperCase(Letter);
if(Letter == 'M'){return Letter;}
else if(Letter == 'F'){return Letter;}
else{
Print("Choose M or F");
return Check_Gender(User_Input().charAt(0));
}
}
private static Characters Check_Choice(char Letter){
Letter = Character.toUpperCase(Letter);
if(Letter == 'A'){
return new Archer(50,2,10);
}
else if(Letter == ('K')){
return new Knight(100,1,20);
}
else if(Letter ==('W')){
return new Wizard(25,5,5);
}
else{
Print("Choose one of the correct options:Archer(A), Knight(K) or Wizard(W)");
return Check_Choice(User_Input().charAt(0));
}
}
private static int Exception_Catcher(){ //exception handling for when the user enters a non numerical value
try{
return Check_Age(Integer.parseInt(User_Input()));
}
catch (Exception e){
Print("That's not a correct number format, try again");
return Exception_Catcher();
}
}
private static int Check_Age(int Age){
if (Age <= 0) {
Print("You are not alive apparently");
return Exception_Catcher();
} else if (Age > 120) {
Print("You are not that old!! stop being silly");
return Exception_Catcher();
} else {
return Age;
}
}
}
Once my Map object and the Player object gets created, I want to pass it onto Game in order to procedurally create graphics for the game. I tried constructing the Game class to call the method Start however it requires a 'Stage' however when I create a default stage and pass it as an argument it throws multiple exceptions.

You need to start your game from Application.launch(args) so consider the following structure :
public class Game extends Application{
private Player player;
private Map map;
#Override
public void start(Stage primaryStage) throws Exception {
MainMenu mm = new MainMenu();
player = mm.getPlayer();
map = mm.getMap();
//rest of the code remains the same
}
public static void main(String[] args) {
launch(args);
}
}
MainMenu only receives user input and constructs a Player and a Map:
public class MainMenu {
private String name,age,gender,chosenCharacter;
private final Player player;
private final Map map;
public MainMenu() {
getUserInput();
player = new Player(name,age,gender,chosenCharacter);
map = new Map(25,25 , player);
}
private void getUserInput(){ // returns Users response
//todo
}
Player getPlayer() {
return player;
}
Map getMap() {
return map;
}
}
A better option is to get user input by using GUI:
public class GetUserInput {
private Player player;
private Map map;
private final TextField nameTf, ageTf, genderTf, characterTf;
GetUserInput() {
Dialog<Void> dialog = new Dialog<>();
dialog.setTitle("Game Setting");
dialog.setHeaderText("Please enter your prefrences");
// Set the button types.
ButtonType buttonType = new ButtonType("OK", ButtonData.OK_DONE);
dialog.getDialogPane().getButtonTypes().addAll(buttonType, ButtonType.CANCEL);
//Add event handler to ok button
Button okButton = (Button) dialog.getDialogPane().lookupButton(buttonType);
okButton.setOnAction(e-> processInput());
//todo hanlde response when cancel button is pressed
// Create labels and fields.
GridPane grid = new GridPane();
grid.setHgap(10);
grid.setVgap(10);
grid.setPadding(new Insets(20, 150, 10, 10));
nameTf = new TextField();
nameTf.setPromptText("Name");
ageTf = new TextField();
ageTf.setPromptText("Age");
genderTf = new TextField();
genderTf.setPromptText("Gender");
characterTf = new TextField();
characterTf.setPromptText("Character");
//todo add validation to all text fields
grid.add(new Label("Name:"), 0, 0);
grid.add(nameTf, 1, 0);
grid.add(new Label("Age:"), 0, 1);
grid.add(ageTf, 1, 1);
grid.add(new Label("Gender:"), 0, 2);
grid.add(genderTf, 1, 2);
grid.add(new Label("Character:"), 0, 3);
grid.add(characterTf, 1, 3);
dialog.getDialogPane().setContent(grid);
// Request focus on the name field
Platform.runLater(() -> nameTf.requestFocus());
dialog.showAndWait();
}
private void processInput() {
String name = nameTf.getText();
String age = ageTf.getText();
String gender = genderTf.getText();
String chosenCharacter = characterTf.getText();
player = new Player(name,age,gender,chosenCharacter);
map = new Map(25,25 , player);
}
Player getPlayer() {
return player;
}
Map getMap() {
return map;
}
}
And use it by:
GetUserInput getUserInput = new GetUserInput();
player = getUserInput.getPlayer();
map = getUserInput.getMap();

One thing to remember is that your user interface isn't just a random collection of JavaFX components, but includes your code. Therefore you can put your code wherever you wish. Well, sort of.
I would create an object to store much of my state, perhaps calling this Game. Every Event subclass that exists might reference this to decide what the next state of the game should be.
If this is a zork-like game (many rooms, objects to pick up and discard, many exits) I would create an array of Room's, each Room would either be a Room object or a subclass of Room, depending on how difficult the room is. Objects would just be a base "Thing" class, with possible subclasses depending on what the thing was supposed to do. Each Room would describe its exits to the program, which would create the proper buttons. Some rooms would allow the player to do something inside the room ("wash hands in the pool" maybe) and there would be responses for some of them, and generic responses for others ("I don't know how to do that, Dave.").
Most of the buttons would be for exits. The EventHandler for the button would contain information from the Room about which new room to enter.

Trouble determining how to make my calculator calculate properly

This is probably the nth time you've received a newbie question regarding calculators, but I just can't figure it out, been working on it for two to three days. The way I have built my calculator at the moment does not suffice and I know I have to start calculating at the time I press the '=' button, but I simply can't figure out how to do so. Due to this reason I have reverted back to my original calculator code, in which it calculates when I press an operation button (like '+') which didn't work, but I was hoping that that would allow me to properly build on it. Here's the code:
package rekenmachine;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
import java.util.*;
public class Rekenmachine extends JFrame
{
public static void main(String[] args)
{
JFrame frame = new JFrame();
frame.setSize(300,500);
frame.setLocation(800,400);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setTitle("Rekenmachine");
RekenPaneel rekenpaneel = new RekenPaneel();
frame.setContentPane(rekenpaneel);
frame.setVisible(true);
}
private static int getal, totaalGetal;
private boolean optellen, aftrekken, vermenigvuldigen, delen;
public int Optellen(int getal)
{
reset();
optellen = true;
totaalGetal += getal;
getal = 0;
return totaalGetal;
}
public int Aftrekken(int getal)
{
reset();
aftrekken = true;
totaalGetal -= getal;
getal = 0;
return totaalGetal;
}
public int Delen(int getal)
{
reset();
delen = true;
totaalGetal /= getal;
getal = 0;
return totaalGetal;
}
public int Vermenigvuldigen(int getal)
{
reset();
vermenigvuldigen = true;
totaalGetal *= getal;
getal = 0;
return totaalGetal;
}
public int getGetal()
{
return getal;
}
public int getTotaalGetal()
{
return totaalGetal;
}
public void reset()
{
optellen = false;
aftrekken = false;
delen = false;
vermenigvuldigen = false;
getal = 0;
totaalGetal = 0;
}
}
class RekenPaneel extends JPanel
{
JButton knop0, knop1, knop2, knop3, knop4, knop5, knop6, knop7, knop8, knop9,
knopOptel, knopAftrek, knopVermenigvuldigen, knopDelen, knopUitkomst,
knopWissen;
JTextField invoerVak;
JPanel textPaneel, knopPaneel, logoPaneel;
Rekenmachine rekenmachine;
public RekenPaneel()
{
rekenmachine = new Rekenmachine();
setLayout(new BorderLayout());
textPaneel = new JPanel();
knopPaneel = new JPanel();
logoPaneel = new JPanel();
textPaneel.setLayout(new FlowLayout());
knopPaneel.setLayout(new GridLayout(4,4));
logoPaneel.setLayout(new FlowLayout());
Border rand = BorderFactory.createEmptyBorder(10, 10, 10, 10);
knop0 = new JButton("0");
knop0.addActionListener(new knop0Handler());
knop1 = new JButton("1");
knop1.addActionListener(new knop1Handler());
knop2 = new JButton("2");
knop2.addActionListener(new knop2Handler());
knop3 = new JButton("3");
knop3.addActionListener(new knop3Handler());
knop4 = new JButton("4");
knop4.addActionListener(new knop4Handler());
knop5 = new JButton("5");
knop5.addActionListener(new knop5Handler());
knop6 = new JButton("6");
knop6.addActionListener(new knop6Handler());
knop7 = new JButton("7");
knop7.addActionListener(new knop7Handler());
knop8 = new JButton("8");
knop8.addActionListener(new knop8Handler());
knop9 = new JButton("9");
knop9.addActionListener(new knop9Handler());
knopOptel = new JButton("+");
knopOptel.addActionListener(new knopOptelHandler());
knopAftrek = new JButton("-");
knopAftrek.addActionListener(new knopAftrekHandler());
knopVermenigvuldigen = new JButton("*");
knopVermenigvuldigen.addActionListener(new knopVermenigvuldigenHandler());
knopDelen = new JButton("/");
knopDelen.addActionListener(new knopDelenHandler());
knopUitkomst = new JButton("=");
knopUitkomst.addActionListener(new knopUitkomstHandler());
knopWissen = new JButton("C");
knopWissen.addActionListener(new knopWissenHandler());
invoerVak = new JTextField(25);
invoerVak.setHorizontalAlignment(invoerVak.RIGHT);
invoerVak.setEditable(false);
invoerVak.setBackground(Color.WHITE);
textPaneel.add(invoerVak);
knopPaneel.add(knop7);
knopPaneel.add(knop8);
knopPaneel.add(knop9);
knopPaneel.add(knopDelen);
knopPaneel.add(knop4);
knopPaneel.add(knop5);
knopPaneel.add(knop6);
knopPaneel.add(knopVermenigvuldigen);
knopPaneel.add(knop1);
knopPaneel.add(knop2);
knopPaneel.add(knop3);
knopPaneel.add(knopOptel);
knopPaneel.add(knop0);
knopPaneel.add(knopWissen);
knopPaneel.add(knopUitkomst);
knopPaneel.add(knopAftrek);
add(textPaneel, BorderLayout.NORTH);
add(knopPaneel, BorderLayout.CENTER);
add(logoPaneel, BorderLayout.SOUTH);
}
class knop0Handler implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
invoerVak.setText(invoerVak.getText() + "0");
}
}
class knop1Handler implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
invoerVak.setText(invoerVak.getText() + "1");
}
}
class knop2Handler implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
invoerVak.setText(invoerVak.getText() + "2");
}
}
class knop3Handler implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
invoerVak.setText(invoerVak.getText() + "3");
}
}
class knop4Handler implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
invoerVak.setText(invoerVak.getText() + "4");
}
}
class knop5Handler implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
invoerVak.setText(invoerVak.getText() + "5");
}
}
class knop6Handler implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
invoerVak.setText(invoerVak.getText() + "6");
}
}
class knop7Handler implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
invoerVak.setText(invoerVak.getText() + "7");
}
}
class knop8Handler implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
invoerVak.setText(invoerVak.getText() + "8");
}
}
class knop9Handler implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
invoerVak.setText(invoerVak.getText() + "9");
}
}
class knopOptelHandler implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
String invoer = invoerVak.getText();
int invoerGetal = Integer.parseInt(invoer);
rekenmachine.Optellen(invoerGetal);
invoerVak.setText("");
}
}
class knopAftrekHandler implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
String invoer = invoerVak.getText();
int invoerGetal = Integer.parseInt(invoer);
rekenmachine.Aftrekken(invoerGetal);
invoerVak.setText("");
}
}
class knopVermenigvuldigenHandler implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
String invoer = invoerVak.getText();
int invoerGetal = Integer.parseInt(invoer);
rekenmachine.Vermenigvuldigen(invoerGetal);
invoerVak.setText("");
}
}
class knopDelenHandler implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
String invoer = invoerVak.getText();
int invoerGetal = Integer.parseInt(invoer);
rekenmachine.Delen(invoerGetal);
invoerVak.setText("");
}
}
class knopUitkomstHandler implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
invoerVak.setText("" + rekenmachine.getTotaalGetal());
rekenmachine.reset();
}
}
class knopWissenHandler implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
rekenmachine.reset();
invoerVak.setText("");
}
}
}
What it basically does is look like a calculator, all buttons work, yet the way it calculates is way off, if at all. I think what I need to do is save a number, when I press + it should add the next number, if I press - it should substract the next number, if I press * it should multiply by the next number and if I press / it should divide by the next number, then when I press = it should show the result, yet I have no idea how to do that.
Should it be done with an arraylist? If so, how could I properly save the result? I mean, using it with two numbers isn't that hard, you just save two numbers and do something with them, then show the result, but a person doesn't always use just two numbers.
To explain the problem I'm having more clearly: for example, when I enter '50' and then press '+' it SHOULD convert "50" to getal = 50 and start the Optellen method, then totaalGetal should become 50, it then empties the textfield. If I then add '3', it should say 53 when I press '=' yet it still shows 50 if I'm lucky. To solve that I assume I have to make the calculation WHEN I press '=' but I don't know how to save/calculate numbers before having done that.
Can anybody tell me what to do before I've lost all my hair? :P

When you click on the +, you're calling this:
knopOptel.addActionListener((ActionEvent e) ->
{
String invoer = invoerVak.getText();
int invoerGetal = Integer.parseInt(invoer);
rekenmachine.addition(invoerGetal);
invoerVak.setText("");
});
But when you click on +, you're not doing the calculation yet! What you should be doing is:
The user type a number
The user click on + (for example)
In your ActionListener, you read the number on the screen, you store it in getal, you clear the screen, and you set your boolean optel to true
The user types another number
The user click on equal
In your equal Listener, you read the number you read the number on the screen, and depending on the flag (optel in the example), you calculate the result
you display the result
So indeed, the calculation is done when you press equal.
A small code example:
knopOptel.addActionListener((ActionEvent e) ->
{
int invoerGetal = Integer.parseInt(invoerVak.getText()); // get the number
calculate(invoerGetal); //sets totalNumber to what it should be by looking at the flags
invoerVak.setText(totalNumber); // we write the temporary result
additionFlag = true; // next number must be added
});
And your calculate function should just be something like:
private void calculate(int aInvoerGetal) {
if (addition)
totalNumber += aInvoerGetal;
else if (substract)
totalNumber -= aInvoerGetal;
else if (divide)
totalNumber /= aInvoerGetal;
else if (multiply)
totalNumber *= aInvoerGetal;
resetFlags();
}
TO GO FURTHER:
Now, if you want to support multiple caculations (5+5+5+3), it's easy. When you click on +, -, *, /, you first call the equalActionListener.
This way, you get this kind of sequence:
5, + // ==> equal called ==> 5 (because the flags are all false) ==> flag + to true
10, + // ==> equal called ==> 15 because 5 in memory and + flag was on. + flag goes off, then on again (because you pressed + again)
4, = // ==> equal called ==> 19

When developing something, you have to think first how you want to solve a problem. Work from there by designing a solution. If you have a programmable solution, implement it. The UI may come later. That's a core skill that a developer should have.
1) You want to have a calculator that support +, -, / and *. The output should be shown if "=" is clicked.
2) Think with classes. That concept may be new for you, but you will discover later from. Your main class that does the calculations is Rekenmachine. (From a design perspective, it should be a stand alone class, but that's not important now). You need to separate it from your UI layer.
Your class supports the actions that you have implemented with the UI. That's good. But I also see things that shouldn't be there
public int Vermenigvuldigen(int getal)
{
reset(); // reset the calculator ?
vermenigvuldigen = true; // purpose ?
totaalGetal *= getal;
getal = 0; // resetting argument getal ?
return totaalGetal;
}
Here, I'm not sure why you're calling reset() because what it does is
public void reset()
{
optellen = false;
aftrekken = false;
delen = false;
vermenigvuldigen = false;
getal = 0;
totaalGetal = 0;
}
When reading the above method, you see that it resets the value that you tried to add on. Of course your calculation would go wrong because you're erasing previous data... resetting everything back to initial state. I also don't understand the setting to "true" or "false" on the actions. Perhaps for the UI? That is not required.
Make it simple:
When creating Rekenmachine, set the variable totaalGetal to 0 as default. That variable holds the value of your calculations performed so far. That's the start. When you have an addition, use
public void add(int getal) {
totaalGetal+= getal; // means totaalGetal = totaalGetal + getal.
}
Before calling add() you have to parse the string to an integer. This can be done in the button action:
class knop1Handler implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
// get input
String input = invoerVak.getText();
// convert
int converted = convertToInt(input);
// instruct myRekenmachine to add the value
myRekenmachine.add(converted);
}
}
Important note ... use concise naming ... "knop1handler" is difficult to read. Use "addButtonHandler" to indicate that this class handles the add button.
convertToInt is a method that reads in a String and returns with an integer. You have to implement that yourself. myRekenmachine is an instance of your Rekenmachine class.
This above is for addition. Implement the same for other operands. If you want to adjust the UI, do that in the handler.
Now, when you press =, just return the totaalGetal value.
PS: Not sure, but ask if you are allowed to write names in English. My native language is Dutch, but during my CS courses, I am allowed to program completely in English. Please try to ask it because English is the main language in IT world if you're aiming for a career in IT.

Wesley, did you think about what you wanted the calculator to do before you started coding? e.g. would it support brackets, sin/cos, memory. Did you think about how logically these functions would work and then think of how they could be implemented in Java? A few flow charts and some pesudocode can go a long way when you're starting out in a new language if only to help you comprehend what it is you are trying to do.
BTW I know it's tempting to start with the GUI code and move into the logic of the application but it is usually better to start with the logic and then move onto the GUI. You can hard code the values for inputs and see if the functionaly behaves as expected and then introduce parameters with values passed in from else where.
EDIT
I think I know why your + key is not working. The reset() method is setting getal and totalGetal to 0 before adding them. 0 + 0 is 0.
knopOptel = new JButton("+");
knopOptel.addActionListener(new knopOptelHandler());
class knopOptelHandler implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
String invoer = invoerVak.getText();
int invoerGetal = Integer.parseInt(invoer);
rekenmachine.Optellen(invoerGetal);
invoerVak.setText("");
}
}
public int Optellen(int getal)
{
reset();
public void reset()
{
optellen = false;
aftrekken = false;
delen = false;
vermenigvuldigen = false;
getal = 0;
totaalGetal = 0;
}
optellen = true;
totaalGetal += getal;
getal = 0;
return totaalGetal;
}

I'm probably doing this incorrectly. Is there a better way?

So usually when I make mock-up programs (like this one) I look for things I can improve on in case the situation happens again.
Today I thought I'd brush up on basic OOP (I understand the concept of OOP, just haven't messed around with it for a bit and wanted to freshen my memory). So I decided to make a little game that just creates 3 monsters on a 10x10 plane and 1 player (you), you are able to move your player in any x/y direction. My program works but I can't help but feel that I'm doing something incorrectly.
So the basic layout of my program was to have 5 classes. A GUI class that shows the game and gives you directional buttons for movement control, a class that creates the monsters, a class that creates the players, a class that creates the 10x10 board and keeps track of monster/player locations, and of course a main class that creates all the objects and has the main game loop and whatnot.
I was having a bit of a hard time interacting with my main class and my GUI class. What I ended up doing was doing a while loop in my main class and waiting until the player presses the start button, and once the player presses it (via action listener) the GUI class sets a public variable (running) from false to true, and I am able to act accordingly once the variable is changed.
HERE is where I feel like I am doing something wrong: At first my while loop would not terminate unless I printed out to the console. I Googled the issue and apparently people have said that it's some sort of issue with threading or "active polling", which I did not understand. I went to my program and added a small 10ms thread sleep in my while loops and everything started working great.
My question to you guys is, what is active polling? Why is it bad? How/why/where was this going on in my program? And finally if there's a better way of interacting with a GUI class and a main class. Sorry for the giant wall of text but I like to be thorough when explaining a situation!
TL;DR: Am I interacting correctly with my GUI class and my main class? If not what is the proper way to do it?
My main class:
public class MainGame {
public static void main(String[] args) throws InterruptedException{
ShowGUI gui = new ShowGUI();
while(!gui.running){
Thread.sleep(10);
}
Board gameBoard = new Board();
gui.setLabelText(gameBoard.getBoard());
//Add Player
Player playerOne = new Player(1000, "Player 1");
//Add monsters
Monster monstMatt = new Monster(1000, "Matt");
Monster monstJon = new Monster(1000, "Jon");
Monster monstAbaad = new Monster(1000, "Abaad");
while(gui.running){
Thread.sleep(10);
int x, y;
x = playerOne.getX();
y = playerOne.getY();
if(gui.buttonPress != -1){
if(gui.buttonPress == 1){
playerOne.move(x, --y);
}else if(gui.buttonPress == 2){
playerOne.move(x, ++y);
}else if(gui.buttonPress == 3){
playerOne.move(--x, y);
}else if(gui.buttonPress == 4){
playerOne.move(++x, y);
}
gui.buttonPress = -1;
gui.setLabelText(gameBoard.getBoard());
}
}
}
}
My GUI Class:
public class ShowGUI{
private JTextArea board;
private JButton moveUp;
private JButton moveDown;
private JButton moveLeft;
private JButton moveRight;
public boolean running = false;
public int buttonPress = -1;
public ShowGUI(){
System.out.println("GUI Successfully Loaded");
createAndShow();
}
private void createAndShow(){
JFrame mainFrame = new JFrame("Bad Game");
addComponents(mainFrame.getContentPane());
mainFrame.setSize(500, 400);
mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mainFrame.setLocationRelativeTo(null);
mainFrame.setResizable(false);
mainFrame.setVisible(true);
}
private void addComponents(Container pane){
pane.setLayout(null);
board = new JTextArea(1, JLabel.CENTER);
moveUp = new JButton("Up");
moveDown = new JButton("Down");
moveLeft = new JButton("Left");
moveRight = new JButton("Right");
moveUp.setBounds(185, 225, 130, 35);
moveLeft.setBounds(115, 280, 130, 35);
moveRight.setBounds(255, 280, 130, 35);
moveDown.setBounds(185, 335, 130, 35);
board.setEditable(false);
board.setBounds(115, 30, 270, 145);
board.setFont(new Font("Consolas", Font.BOLD, 12));
addActionListeners();
pane.add(board);
pane.add(moveUp);
pane.add(moveRight);
pane.add(moveLeft);
pane.add(moveDown);
}
private void addActionListeners(){
moveUp.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
running = true;
buttonPress = 1;
}
});
moveDown.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
buttonPress = 2;
}
});
moveLeft.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
buttonPress = 3;
}
});
moveRight.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
buttonPress = 4;
}
});
}
public void setLabelText(char[][] boardToShow){
board.setText(" ");
for(int i = 0; i < boardToShow.length; i++){
for(int j = 0; j < boardToShow[i].length; j++){
board.append(boardToShow[i][j] + " ");
}
board.append("\n ");
}
}
}
If you require my Board/Monster/Player classes I can post them, but I don't think the problem is with those classes.

Active polling (a.k.a. busy waiting) is when a program checks over and over whether some condition is true, and since we're talking about computers, this is usually done many times a second. It's bad because it means the process is constantly using up CPU to check for this condition, and, even worse, because it uses up so much of the CPU, it can prevent the condition from being able to become true in the first place (this is what is happening in your case).
I'll try to explain this with a metaphor, where your Main class (specifically your while(gui.running) loop) is the boss, and the GUI class is the employee. Imagine the boss comes to his employee every second and asks "Have you done what I asked you to do?". By doing so every second, not only is the boss wasting his time, but is actually preventing his employee from being able to do what he was asked to do.
That is exactly what is happening between your Main and GUI class. The value of buttonPress can not change when the while loop keeps running, and that's why sleeping (and printing to console, because that requires an IO operation which also blocks the thread for a while) makes it work, because the while loop stops executing for a short amount of time, giving your program the chance to change the value of buttonPress.
The solution
In order to solve this, let's go back to the boss/employee metaphor. Instead of checking every second, the boss should say, "When you are done doing this, come and tell me". That way he doesn't need to keep checking on the employee and the employee has time to do the task. Similarly, your GUI class should call a method in your Main class when the actionListeners are fired. Ultimately, as other people pointed out, your structure needs quite a bit of work and clean up, I would recommend you look into using the Model-View-Controller pattern.
However I will propose a solution which will work for the setup you currently have. Your Main class should look something like:
public class Main {
private Player playerOne;
private Monster monstMatt;
private Monster monstJon;
private Monster monstAbaad;
private ShowGUI gui;
private Board gameBoard;
public Main() {
//Add Player
playerOne = new Player(1000, "Player 1");
//Add monsters
monstMatt = new Monster(1000, "Matt");
monstJon = new Monster(1000, "Jon");
monstAbaad = new Monster(1000, "Abaad");
gui = new ShowGUI(this);
gameBoard = new Board();
gui.setLabelText(gameBoard.getBoard());
}
public movePlayerUp() {
movePlayer(0, -1);
}
public movePlayerDown() {
movePlayer(0, 1);
}
public movePlayerLeft() {
movePlayer(-1, 0);
}
public movePlayerRight() {
movePlayer(1, 0);
}
private movePlayer(x, y) {
playerOne.move(playerOne.getX() + x, playerOne.getY() + y);
}
}
And the GUI class:
public class ShowGUI {
private Main main;
public ShowGui(Main main) {
this.main = main;
createAndShow();
System.out.println("GUI Successfully Loaded");
}
private void addActionListeners(){
moveUp.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
main.movePlayerUp();
}
});
moveDown.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
main.movePlayerDown();
}
});
moveLeft.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
main.movePlayerLeft();
}
});
moveRight.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
main.movePlayerRight();
}
});
}
/* All the other methods you have */
...
}
So instead of using flags (buttonPress=2), use methods which will be called when a certain action occurs. Again, this is not a perfect long-term solution, but it has the right gist and is the sort of pattern you should follow.

Modifying a JTextField after reading String from another JTextField

Having some problems updating a JTextField in a different class after reading a String from another JTextField. Here's the method in question:
public JTextField buyVowel(playerPlate player)
{
String get = input.getText();
String[] vowels = new String[]{"a","e","i","o","u"};
for(int i =0; i<vowels.length; i++)
{
if(get.equals(vowels[i]))
{
player.pMoney =- 250;
player.playerMoney.setText("$"+player.pMoney);
}
}
return player.playerMoney;
}
playerPlate is a separate class.
I'm using this method to determine what player the program should be modifying:
public playerPlate getCurrentPlayer()
{
if(currentPlayer == 1)
{
return player1;
}
else if(currentPlayer == 2)
{
return player2;
}
else
{
return player3;
}
}
player(s) 1, 2, and 3 are instances of playerPlate.
I want it to be modifying instance variables in this class:
package wheelOfFortune;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class playerPlate extends JPanel
implements ActionListener
{
public String pName;
public int pMoney = 500;
public int currentPlayer;
public JTextField playerMoney;
public playerPlate(String player, Color color, int currentPlayer)
{
setBorder(BorderFactory.createLineBorder(Color.BLACK,2));
setBackground(color);
pName = player;
JTextField playerNames = new JTextField(pName);
playerNames.setBorder(BorderFactory.createLineBorder(Color.BLACK,2));
playerNames.setEditable(false);
playerNames.setFont(new Font("Impact", Font.PLAIN, 24));
playerNames.setHorizontalAlignment(JTextField.CENTER);
playerNames.setBackground(Color.WHITE);
JTextField playerMoney = new JTextField("$"+pMoney);
playerMoney.setBorder(BorderFactory.createLineBorder(Color.BLACK,2));
playerMoney.setEditable(false);
playerMoney.setFont(new Font("Impact", Font.BOLD, 32));
playerMoney.setHorizontalAlignment(JTextField.CENTER);
playerMoney.setBackground(Color.WHITE);
Box b1 = Box.createVerticalBox();
b1.add(playerNames);
b1.add(Box.createVerticalStrut(5));
Box b2 = Box.createHorizontalBox();
b2.add(Box.createHorizontalStrut(60));
Box b3 = Box.createVerticalBox();
b3.add(playerMoney);
b3.add(Box.createVerticalStrut(8));
b2.add(b3);
b1.add(b2);
b1.add(Box.createVerticalStrut(5));
add(b1);
}
public void actionPerformed(ActionEvent e)
{
}
}
Here is the actionPerformed method within the main class:
public void actionPerformed(ActionEvent e)
{
JButton b = (JButton)e.getSource();
if(b==spin)
{
spinWheel(wheelStuff);
repaint();
}
if(b==next)
{
updatePlayer();
repaint();
}
if(b==reset)
{
letterBoard.reset();
updateCat();
repaint();
}
if(b==buyVowel)
{
buyVowel(getCurrentPlayer());
repaint();
}
}
The gist of what I want to happen, is when the user types a vowel into JTextField input, and clicks JButton buyVowel it subtracts $250 from their total money (pMoney). And displays the change on the GUI. After tinkering with this for a couple hours, I honestly have no idea why this isn't working. I keep receiving nullPointerExceptions when trying to use it. Thanks for your help.
Note: everything except for class playerPlate is in the same class. playerPlate is in a separate class.

You're shadowing the variable playerMoney in the constructor of playerPlate. The method buyVowel relies on playerPlate being instantiated when invoking setText, otherwise a NullPointerException will be thrown. Replace
JTextField playerMoney = new JTextField("$"+pMoney);
with
playerMoney = new JTextField("$"+pMoney);
Aside: Java naming conventions indicate that class names start with uppcase letters so use class names such as PlayerPlate.

Memory Game in java

I am trying to write a memory game. When we run app, "menu" appears first. The choices are one player and two player. When we click one player "level" selection part appears. Here choices are easy, medium, hard. Then one of them is clicked and game starts. But i am having trouble while implementing how to check selected cards equal or not. When a card is created, an id is assigned to it. And when two cards are clicked, I am checking ids. If ids are same, it returns "match", if it is not then "close" returns that means cards turn facedown. I am using MVC pattern. I have 9 classes. Card, Game, Level(enum), Menu, State(enum); views CardButton, GamePanel, LevelPanel, MenuPanel.
Class GamePanel:
package view;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import model.Game;
import model.State;
public class GamePanel extends JPanel {
private Game model;
ActionListener cardButtonActionListener;
private JFrame frame;
public GamePanel(Game gameModel, JFrame frame) {
int width=gameModel.getRowSize();
int height=gameModel.getColumnSize();
setLayout(new GridLayout(width,height));
this.model = gameModel;
this.cardButtonActionListener = new CardButtonActionListener();
this.frame = frame;
show();
}
public void show() {
for(int row=0; row<model.getRowSize(); row++) {
for (int col=0; col<model.getColumnSize(); col++) {
CardButton cardBtn = new CardButton(model.getCard(row, col));
cardBtn.addActionListener(cardButtonActionListener);
add(cardBtn);
}
}
frame.repaint();
}
public class CardButtonActionListener implements ActionListener {
private int i = 0;
CardButton b ,b2;
State currentState;
#Override
public void actionPerformed(ActionEvent e) {
if(i==0){
b = (CardButton) e.getSource();
b.setFaceUp();
JOptionPane.showInputDialog("id "+b.getCard().getValue());
i++;
}
else{
b2 = (CardButton) e.getSource();
b2.setFaceUp();
i--;
}
currentState = model.compareCards(b, b2);
if(currentState == State.Match){
b.setVisible(false);
b2.setVisible(false);
}
if(currentState == State.Close){
b.setFaceDown();
b2.setFaceDown();
}
if(currentState == State.Continue){
}
}
}
}
Class Game:
package model;
import java.util.ArrayList;
import java.util.Collections;
import javax.swing.JPanel;
import view.CardButton;
public class Game extends JPanel {
private Level level;
private ArrayList<ArrayList<Card>> board;
private int rowSize;
private int colSize;
private ArrayList<Card> cardList;
public Game() {
}
public void setLevel(Level level,int x) {
this.level = level;
initBoard(x);
}
private void initBoard(int x) {
// Create board according to level variable
int s = x;
rowSize = s;
colSize = s;
int a=rowSize*colSize/2;
int b=0;
this.board = new ArrayList<ArrayList<Card>>();
for(int row=0; row<s; row++) {
this.cardList = new ArrayList<Card>();
for (int col=0; col<s/2; col++) {
cardList.add(new Card(b));
cardList.add(new Card(b));
b++;
}
board.add(getCardList());
}
Collections.shuffle(board);
}
public ArrayList<Card> getCardList(){
Collections.shuffle(cardList);
return cardList;
}
public int getRowSize() {
return rowSize;
}
public int getColumnSize() {
return colSize;
}
public Card getCard(int row, int col) {
return board.get(row).get(col);
}
public State compareCards(CardButton b, CardButton b2) {
int v1, v2;
v1 = b.getCard().getValue();
v2 = b2.getCard().getValue();
if(b.getCard()!= null && b2.getCard()!= null){
return State.Continue;
}else{
if(v1 == v2){
return State.Match;
}
else{
return State.Close;
}
}
}
}
GamePanel takes state info and decides card which position card should stay: faceup, facedown. But I couldn t implement action performed method(in GamePanel) and compareCards method(in Game) correctly. When I run code, I get null pointer exeption. Because I can not take 2 buttons info. One of them always stays null. I probably need to change this part:
if(i==0){
b = (CardButton) e.getSource();
b.setFaceUp();
JOptionPane.showInputDialog("id "+b.getCard().getValue());
i++;
}
else{
b2 = (CardButton) e.getSource();
b2.setFaceUp();
i--;
}
But I don t know how I can correct. Thank you.
Edit: Whole project is here http://cnv.as/21qoh

The b and b2 variables are null when the CardButtonActionListener is created. So the first time actionPerformed() is called and you fall through your if(i==0) conditional statement, only one of b or b2 gets assigned the return value from e.getSource(). So when you call currentState = model.compareCards(b, b2); either b or b2 will still be null which as you found out will cause that method to throw a null pointer exception.
It looks like this isn't so much a coding error as it is that your design needs some additions. The main reason is each card has its own instance of CardButtonActionListener and when clicked, this listener class isn't aware of any other cards that have already been clicked. For a quick remedy to this you could add a public static Card lastClicked; member variable to your Game class (disclaimer: note I said 'quick', not 'good' as this violates good OOP design and in a multithreaded app would give you tons of trouble... but for a single threaded app like yours if you just want it to work this may be ok for you - but be warned that using public static variables like this is definitely not a good habit to get into). Then you could modify your CardButtonActionListener.actionPerformed() like this (note that I did away with the 'i' variable):
#Override
public void actionPerformed(ActionEvent e) {
CardButton justClickedButton = e.getSource();
justClickedButton.setFaceUp();
CardButton previouslyClickedButton = Game.lastClicked;
if(previouslyClickedButton == null){
JOptionPane.showInputDialog("id "+justClickedButton.getCard().getValue());
previouslyClickedButton = justClickedButton;
}
else{
currentState = model.compareCards(justClickedButton, previouslyClickedButton);
if(currentState == State.Match){
justClickedButton.setVisible(false);
previouslyClickedButton.setVisible(false);
}
if(currentState == State.Close){
justClickedButton.setFaceDown();
previouslyClickedButton.setFaceDown();
}
if(currentState == State.Continue){
}
previouslyClickedButton = null;
}
}