Question

I’m having trouble; I’m trying to implement a cinema booking system however I cannot set an actionListener to a specific button on different grids. The way I want it to work is each user will have a session in which he can pick seats and a ticket price such as student rate, old age pensionate rates. Anyway, I cannot seem to be able to add actionListener, so when he picks seats, those become unavailable while the program is running. Thank you.

// Load Libraries
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class cinemaSystem {
    // Global Variables
    JFrame frame = new JFrame(); // Creates JFrame
    JLabel title;
    JButton l[][], m[][], r[][]; // Names grid of JButtons
    JPanel panel1, panel2, panel3;

    // Constructor
    public cinemaSystem(){

            title = new JLabel("Cinema Booking");
            title.setFont(new Font("Helvetica", Font.BOLD, 30));
            title.setLocation(12,5);
            title.setSize(600, 60);

            frame.setLayout(null); // Setting Grid Layout
            // panel1.setLayout(new GridLayout(seat,row));
            l = new JButton[4][4]; // Allocating Size of Grid
            panel1 = new JPanel(new GridLayout(4,4));
            panel1.setBackground(Color.black);
            panel1.setBounds(20, 70, 200, 140);
            for(int y = 0; y <4 ; y++){
                    for(int x = 0; x < 4; x++){
                        l[x][y] = new JButton("L" + y + x); // Creates New JButton
                        // l[x][y].addActionListener(this);
                        panel1.add(l[x][y]); //adds button to grid
                    }
            }

            m = new JButton[4][2]; // Allocating Size of Grid
            panel2 = new JPanel(new GridLayout(2,4));
            panel2.setBackground(Color.black);
            panel2.setBounds(240, 140, 200, 70);
            for(int y = 0; y <2 ; y++){
                    for(int x = 0; x < 4; x++){
                        m[x][y] = new JButton("M" + y + x); // Creates New JButton
                        panel2.add(m[x][y]); //adds button to grid
                    }
            }

            r = new JButton[4][4]; // Allocating Size of Grid
            panel3 = new JPanel(new GridLayout(4,4));
            panel3.setBackground(Color.black);
            panel3.setBounds(460, 70, 200, 140);
            for(int y = 0; y <4 ; y++){
                    for(int x = 0; x < 4; x++){
                        r[x][y] = new JButton("R" + y + x); // Creates New JButton
                        panel3.add(r[x][y]); //adds button to grid
                    }
            }

            frame.add(title);
            frame.add(panel1);
            frame.add(panel2);
            frame.add(panel3);
            frame.setPreferredSize(new Dimension(680, 280));
            frame.setTitle("Cinema Booking");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.pack(); //sets appropriate size for frame
            frame.setVisible(true); //makes frame visible
    }

    // Main Class
    public static void main(String[] args) {
            new cinemaSystem(); //makes new ButtonGrid with 2 parameters
    }
}

Answer 1

You can get the text held by the pressed JButton simply by calling getActionCommand() on the ActionEvent object passed into the actionPerformed(...) method, or you can get which button was pressed via its getSource() method. Either of these can help you find the JButton in your arrays and inactivate it.

Other suggestions:

• Don’t use this as your ActionListener. Instead consider using an anonymous inner class or private inner class. This will make your code much more flexible and your ActionListeners much simpler.
• Try to follow Java naming conventions including being sure that class names start with capital letters and that variables and method names begin with lower-case letters. This will make it much easier for others (such as us!) to be able to understand your code at a glance.
• Avoid use of absolute layouts as it makes your GUI’s hard to maintain and doesn’t allow your GUI’s to re-size flexibly for different OS’s or screen resolutions. For instance your current GUI looks like this on my screen:

For example this ActionListener will show which button was pressed and will inactivate that button:

private class MyListener implements ActionListener {
  public void actionPerformed(ActionEvent e) {
     System.out.println("Button pressed: " + e.getActionCommand());
     ((JButton)e.getSource()).setEnabled(false);
  }
}

Which can be added to the JButtons in a fashion similar to this…

  ActionListener listener = new MyListener();

  for (int i = 0; i < leftBtns.length; i++) {
     for (int j = 0; j < leftBtns[i].length; j++) {
        JButton btn = new JButton("L" + i + j);
        btn.setFont(btn.getFont().deriveFont(Font.BOLD, BTN_FONT_SIZE));
        btn.addActionListener(listener);
        leftPanel.add(btn);
     }
  }

Plus using appropriate layout managers produced a GUI that looked like this: