title: Display not Changing
body: <p>I am working on this program that calculates the Beats per Minute (BPM) when you click the button. When you click two times, it is supposed to display the current BPM, and display the new one with every click after that. What the problem is, though, is that the display isn't changing. What do I need to do?</p>
  
  <p>Here is my code:</p>
  
  <pre><code>import java.awt.*;
  import java.awt.event.*;
  import javax.swing.*;
  import java.util.*;
  
  public class BPM extends JPanel implements ActionListener {
      JLabel label;
      public String display;
      public int bpm;
      public int buttonPressed;
      public int time1;
      public int time2;
      public int time3;
      public int counter[];
  
      public void addComponents(Container pane) {
          JPanel buttons = new JPanel();
  
          JButton bpmButton = new JButton("Click");
          bpmButton.setSize(new Dimension(100, 50));
          bpmButton.addActionListener(new ActionListener() {
              public void actionPerformed(ActionEvent e) {
                  buttonPressed++;
                  counter = new int[2];
                  if (buttonPressed == 1) {
                      counter[0] = (int)(System.currentTimeMillis());
                  }   else if (buttonPressed == 2) {
                      counter[1] = (int)(System.currentTimeMillis());
                      calculateTimeBetweenClicks();
                      setTime();
                  }   else {
                      counter[0] = counter[1];
                      counter[1] = (int)(System.currentTimeMillis());
                      calculateTimeBetweenClicks();
                      setTime();
                  }
              }
          });
  
          display = "0";
          label = new JLabel(display, SwingConstants.CENTER);
          label.setFont(label.getFont().deriveFont(100.0f)); // original 45
  
          pane.add(label, BorderLayout.PAGE_START);
          pane.add(bpmButton, BorderLayout.CENTER);
      }
  
      // Calculates the difference between the two saved clicks
      public void calculateTimeBetweenClicks() {
          if (buttonPressed == 1) {
              time1 = counter[0];
          } else {
              time1 = counter[0];
              time2 = counter[1];
          }
          time3 = time2 - time1;
      }
  
      // Calculates the BPM and changes the display accordingly
      public void setTime() {
          bpm = 60000 / time3;
          display = "" + bpm + "";
          label.setText(display);
      }
  
      public void actionPerformed(ActionEvent e) {
          // TODO Auto-generated method stub
  
      }
  
      public static void createAndShowGUI() {
          // Creates the window
          JFrame frame = new JFrame("BPM Calculator");
          frame.setPreferredSize(new Dimension(300, 200)); // original (250, 130)
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  
          // Adds the components to the content pane
          BPM window = new BPM();
          window.addComponents(frame.getContentPane());
  
          //Displays the window.
          frame.pack();
          frame.setVisible(true);
      }
  
      public static void main(String[] args) {
          // Turns off bold text
          UIManager.put("swing.boldMetal", Boolean.FALSE);
  
          // Allows the components to be used and interacted with
          java.awt.EventQueue.invokeLater(new Runnable() {
               public void run() {
                  createAndShowGUI();
               }
          });
      }
  
  }
  </code></pre>