Question

I’m writing a game in Java, and I want the user to be able to provide input from both the command line and my GUI. Currently, I use this method to get input:

    static String getInput(){         System.out.println('Your move:');         Scanner sc = new Scanner(System.in);         return sc.nextLine();     } 

I want to keep using this, but let a mousePressed event emulate the user actually typing in their input as well. It’s not that efficient of a solution, but it makes sense in my application. So the question is: how do I simulate a user typing to System.in from the code side?

Answer 1

This is possible – the easiest substitution for System.in would be a PipedInputStream. This must be hooked up to a PipedOutputStream that writes from another thread (in this case, the Swing thread).

public class GameInput {      private Scanner scanner;      /**CLI constructor*/     public GameInput() {         scanner = new Scanner(System.in);     }      /**GUI constructor*/     public GameInput(PipedOutputStream out) throws IOException {         InputStream in = new PipedInputStream(out);         scanner = new Scanner(in);     }      public String getInput() {         return scanner.nextLine();     }      public static void main(String[] args) throws IOException {         GameInput gameInput;          PipedOutputStream output = new PipedOutputStream();         final PrintWriter writer = new PrintWriter(output);         gameInput = new GameInput(output);          final JTextField textField = new JTextField(30);         final JButton button = new JButton('OK');         button.addActionListener(new ActionListener() {             @Override             public void actionPerformed(ActionEvent e) {                 String data = textField.getText();                 writer.println(data);                 writer.flush();             }         });          JFrame frame = new JFrame();         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);         frame.getContentPane().setLayout(new FlowLayout());         frame.getContentPane().add(textField);         frame.getContentPane().add(button);         frame.pack();         frame.setVisible(true);          String data = gameInput.getInput();         System.out.println('Input=' + data);         System.exit(0);     }  } 

However, it might be better to rethink your game logic to cut out the streams altogether in GUI mode.