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javaswingjtextfield

Event driven input vs turn based


I am trying to recreate console game with JTextArea as console/output and JTextField as user input. Since the GUI is event driven I do not understand how could I stop the code from executing, to wait for user input before proceeding with opponents turn. The only solution I can think of is While(userTurn) and userTurn would be changed to false upon actionlistener is there a better way?

My console solution

 String getInput(String prompt){
        String inputLine = null;
      console.setTextConsole(prompt + " ");
        try{
            BufferedReader is = new BufferedReader(new InputStreamReader(System.in));
            inputLine = is.readLine();
            if(inputLine.length() == 0) return null;

        }catch(IOException e){
            console.setTextConsole("IOException "+e);
        }
        return inputLine;
    }

I just called this getInput method and I proceeded with opponents turn.

What I want to accomplish is:

  1. Opponents turn
  2. Game waits for user
  3. User types text into JtextField and presses enter
  4. Game executes players command
  5. Opponents turn again ..

Solution

  • I've written an example game so you can observe the difference. The computer and the user try to guess a random number between 0-2 inclusive. Who ever gets it right wins. If both get it right or both get it wrong its a draw.

    EDIT: Updated GUI version

    Here's the console program:

    import java.util.Random;
    import java.util.Scanner;
    
    public class ConsoleGame {
        public static void main(String[] args) {
            Scanner console = new Scanner(System.in);
            Random rand = new Random();
            boolean playAgain = false;
            int wins = 0, losses = 0, draw = 0;
            do {
                int num = rand.nextInt(3); // 0-2 inclusive
                System.out.println("Guess the number [0-2]: ");
                int guess = Integer.parseInt(console.nextLine());
                int computerGuess = rand.nextInt(3);
                System.out.println("You: " + guess + "\tComputer: " + computerGuess + "\tNumber: " + num);
                if (guess == num && computerGuess == num || guess != num && computerGuess != num) {
                    draw++;
                    System.out.println("Draw!");
                } else if (guess == num) {
                    wins++;
                    System.out.println("You win!");
                } else if (computerGuess == num) {
                    losses++;
                    System.out.println("Computer wins :(");
                }
                System.out.println("Play again [y/n]? ");
                playAgain = console.nextLine().startsWith("y");
            } while (playAgain);
            System.out.println("Wins: " + wins + "\nLosses: " + losses + "\nDraw: " + draw);
            console.close();
        }
    }
    

    Here's the GUI program:

    import java.awt.BorderLayout;
    import java.awt.Color;
    import java.awt.EventQueue;
    import java.awt.Font;
    import java.awt.event.ActionEvent;
    import java.awt.event.ActionListener;
    import java.util.Random;
    import javax.swing.JFrame;
    import javax.swing.JPanel;
    import javax.swing.JScrollPane;
    import javax.swing.JTextArea;
    import javax.swing.JTextField;
    
    public class GUIGame extends JFrame {
        private JPanel contentPane;
        private JTextField textField;
        private JTextArea textArea;
        private boolean textReceived;
    
         /**
         * Launch the application.
         */
        public static void main(String[] args) {
            EventQueue.invokeLater(new Runnable() {
                @Override
                public void run() {
                    try {
                        GUIGame frame = new GUIGame();
                        frame.setVisible(true);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            });
        }
    
        /**
         * Create the frame.
         */
        public GUIGame() {
            setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            setBounds(100, 100, 450, 300);
            contentPane = new JPanel();
            contentPane.setLayout(new BorderLayout());
            setContentPane(contentPane);
    
            textField = new JTextField();
            textField.addActionListener(new ActionListener() {
                @Override
                // user pressed 'enter' key,
                public void actionPerformed(ActionEvent e) {
                    textReceived = true;
                    synchronized (textField) {
                        // notify game loop thread which is waiting on this event
                        textField.notifyAll();
                    }
                }
            });
            contentPane.add(textField, BorderLayout.SOUTH);
    
            JScrollPane scrollPane = new JScrollPane();
            contentPane.add(scrollPane, BorderLayout.CENTER);
    
            textArea = new JTextArea();
            textArea.setFont(new Font("Consolas", Font.PLAIN, 12));
            textArea.setLineWrap(true);
            textArea.setWrapStyleWord(true);
            textArea.setForeground(Color.LIGHT_GRAY);
            textArea.setBackground(Color.BLACK);
            textArea.setEditable(false);
            scrollPane.setViewportView(textArea);
    
            // Start game loop in new thread since we block the thread when
            // waiting for input and we don't want to block the UI thread
            new Thread(new Runnable() {
                @Override
                public void run() {
                    playGame();
                }
            }).start();
        }
    
        private void playGame() {
            Random rand = new Random();
            boolean playAgain = false;
            int wins = 0, losses = 0, draw = 0;
            do {
                int num = rand.nextInt(3); // 0-2 inclusive
                textArea.append("Guess the number [0-2]: \n");
                int guess = Integer.parseInt(requestInput());
                int computerGuess = rand.nextInt(3);
                textArea.append("You: " + guess + "\tComputer: " + computerGuess + "\tNumber: " + num + "\n");
                if (guess == num && computerGuess == num || guess != num && computerGuess != num) {
                    draw++;
                    textArea.append("Draw!\n");
                } else if (guess == num) {
                    wins++;
                    textArea.append("You win!\n");
                } else if (computerGuess == num) {
                    losses++;
                    textArea.append("Computer wins :(\n");
                }
                textArea.append("Play again [y/n]? \n");
                playAgain = requestInput().startsWith("y");
            } while (playAgain);
            textArea.append("Wins: " + wins + "\nLosses: " + losses + "\nDraw: " + draw + "\n");
        }
    
        private String requestInput() {
            textField.setEnabled(true);
            textField.requestFocus();
            // wait on text field till UI thread signals a user input event
            synchronized (textField) {
                while (!textReceived) {
                    try {
                        textField.wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
            String input = textField.getText();
            textField.setText("");
            textField.setEnabled(false);
            textReceived = false;
            return input;
        }
    }