Start timer (javax.swing) on button-click rather than on its own

Question

I have added a button, that is initially "Please Wait" and changes to "Click Here" as the timer starts. I need to make it so that if the button is clicked, whilst the text is "Please Wait", it starts the timer, rather than having the timer start itself after the 3000ms.

I also am wondering how I could make the restart button, actually restart the test.

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JButton;
import java.awt.FlowLayout;
import java.awt.GridBagLayout;
import java.awt.Dimension;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.Timer;


public class Main extends JFrame implements ActionListener
{
    private static final long serialVersionUID = 1L;
    //Width and Height of the JFrame
    public static final int WIDTH = 550;
    public static final int HEIGHT = 550;
    //Width and Height of the Add Button
    public static final int WIDTH1 = 450;
    public static final int HEIGHT1 = 450;
    //Width and Height of Restart Button
    public static final int WIDTH2 = 125;
    public static final int HEIGHT2 = 25;
    
    //Adding the 3 main components
    //This is the label that counts the clicks
    private JLabel lblValue;
    //This is the integer that counts the clicks
    private int clicks = 0;
    //This is the timer
    private int count = 6;


    public static void main(String[] args)
    {
        // This creates two instances of Main,
        // which creates two different windows.
        Main counter1 = new Main( );
        counter1.setVisible(true);

        Main counter2 = new Main( );
        counter2.setVisible(true);
    }

    public Main( )
    {
        //Title that appears at the top of the page
        setTitle("CPS Test");
        //Close when the close button is pressed
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        //Setting size of the frame
        setSize(WIDTH, HEIGHT);
        setMaximumSize(new Dimension(WIDTH, HEIGHT));
        setMinimumSize(new Dimension(WIDTH, HEIGHT));
        setLayout(new FlowLayout( ));

        // This is the label for the amount of clicks
        lblValue = new JLabel("0");
        //Adding the counter onto the screen
        add(lblValue);
        
        
        //This is the button that adds 1 every time clicked
        JButton addButton = new JButton("Please Wait");
        addButton.addActionListener(this);
        //Setting size for button
        addButton.setSize(new Dimension(WIDTH1, HEIGHT1));
        addButton.setPreferredSize(new Dimension(WIDTH1, HEIGHT1));
        addButton.setMinimumSize(new Dimension(WIDTH1, HEIGHT1));
        addButton.setMaximumSize(new Dimension(WIDTH1, HEIGHT1));
        //Adding button onto screen
        add(addButton);
        
        
        JButton resetButton = new JButton("Restart");
        //Setting size for button
        resetButton.setSize(new Dimension(WIDTH2, HEIGHT2));
        resetButton.setPreferredSize(new Dimension(WIDTH2, HEIGHT2));
        resetButton.setMinimumSize(new Dimension(WIDTH2, HEIGHT2));
        resetButton.setMaximumSize(new Dimension(WIDTH2, HEIGHT2));

        //Adds the label for the timer. This changes after 1000 milliseconds to 1, and then counts every second
        JLabel label = new JLabel("Starting Soon");
        setLayout(new GridBagLayout());
        //Adding timer onto the screen
        add(label);
        
        //Delay in milliseconds between number adding
        Timer timer = new Timer(1000, new ActionListener() {

          public void actionPerformed(ActionEvent e) {
            //Add 1 to count every interval of 1000 milliseconds
              count--;
              //Timer keeps ticking till this number is achieved
            if (count >= 0) {
              label.setText(Integer.toString(count));
            }
            //Will stop timer, remove the click button and will calculate how many clicks you got per second
                else {
              ((Timer) (e.getSource())).stop();
              remove(addButton);
              label.setText("");
              lblValue.setText("You clicked " + clicks / 5d + " clicks per second.");
              add(resetButton);
            }
            //Will change text from "Please Wait" to "Click Here" after timer delay has finished
            if (count == 5) {
                addButton.setText("Click Here");
            }
          }

        });
        //Timer wont start for 3000 milliseconds
        timer.setInitialDelay(3000);
        //Start Timer
        timer.start();

    }
    public void actionPerformed(ActionEvent e)
    {
        String actionCommand = e.getActionCommand( );
        
        //This will only work whilst the text is "Click Here". Wont work for 1000 milliseconds as the text is "Please Wait"
        if (actionCommand.equals("Click Here"))
        {
            //Adds 1 to the click counter ever time it is clicked
            lblValue.setText(Integer.toString(clicks += 1));

        }
    }
}```

1) Declare the `Timer` as an attribute of the class. 2) Set it up ready to go in the constructor. 3) As action listener for the start button (suggest check box or radio button), start it. 4) On action to stop it, .. stop it. **General tip:** For better help sooner, [edit] to add a [MCVE] or [Short, Self Contained, Correct Example](http://www.sscce.org/). It should take no more than 30-40 lines of code to try and implement that approach I just outlined. — Andrew Thompson, Sep 22 '20 at 05:45
When you add an action listener to exactly one component, there is no need to check the contents of the `ActionCommand` property. You demonstrated this yourself by not doing such thing in the action listener attached to the timer. You just correctly assumed that the particular action always is a timer tick. Avoid constructs like `addActionListener(this)`; add a dedicated listener fulfilling one specific purpose. You can use lambda expressions instead of anonymous inner classes to implement an action listener. — Holger, Sep 22 '20 at 07:20

score 4 · Answer 1 · 2020-09-22T13:31:27.807

As Andrew Thompson pointed out, you will have to go through four steps to solve this problem.

1.) The Timer should be a global variable of the class

This step is important because otherwise the object wouldn't be accessible from inside the ActionListeners we are going to create.

import javax.swing.Timer;

public class Test {
  private Timer timer;
  
  public Test() {

  }
}

2.) Create the timer-element in the constructor

In the constructor, we are now going to initialize the timer, but - and this is important - we are not going to to start it yet.

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.Timer;

public class Test {
  private Timer timer;
  private int count = 0;
  
  public Test() {
    ActionListener taskPerformer = new ActionListener() {
      public void actionPerformed(ActionEvent evt) {
        //What should the timer do?
        count++;
        System.out.println(count);
      }
    }; 
    timer = new Timer(1000, taskPerformer);
  }
}

3.) Start the timer in the ActionListener of the start-button

In this step we are adding the functionality to start the timer by pressing a button. For this purpose we are using an ActionListener and the start()-method of the timer.

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.Timer;

public class Test {
  private Timer timer;
  private int count = 0;
  
  public Test() {
    ActionListener taskPerformer = new ActionListener() {
      public void actionPerformed(ActionEvent evt) {
        //What should the timer do?
        count++;
        System.out.println(count);
      }
    }; 
    timer = new Timer(1000, taskPerformer);
    
    JButton start = new JButton("Start");
    
    //Here the functionality is added
    start.addActionListener(new ActionListener() {
      @Override
      public void actionPerformed(ActionEvent arg0) {
        if(!timer.isRunning()) {
          System.out.println("Timer started!");
          timer.start();
        } 
      }
    }); 
  }
}

4.) Stop the timer in the ActionListener of the stop-button

This is basically the other way around. We are going to create another button to add the the functionality to stop the timer. For this purpose we are going to use an ActionListener again and the stop()-method of the timer.

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.Timer;

public class Test {
  private Timer timer;
  private int count = 0;
  
  public Test() {
    ActionListener taskPerformer = new ActionListener() {
      public void actionPerformed(ActionEvent evt) {
        //What should the timer do?
        count++;
        System.out.println(count);
      }
    }; 
    timer = new Timer(1000, taskPerformer);
    
    JButton start = new JButton("Start");
    start.addActionListener(new ActionListener() {
      @Override
      public void actionPerformed(ActionEvent arg0) {
        if(!timer.isRunning()) {
          System.out.println("Timer started!");
          timer.start();
        } 
      }
    });
    
    //Functionality is added here
    JButton stop = new JButton("stop");
    stop.addActionListener(new ActionListener() {
      @Override
      public void actionPerformed(ActionEvent arg0) {
        if(timer.isRunning()) {
          count = 0;
          System.out.println("Timer stopped!");
          timer.stop();
        } 
      }
    });
  }
}

Final step: Create the rest of the GUI

This isn't necessary for answering your question anymore, but I wanted to provide a minimal working example. For this, I am using SwingUtilities.invokeLater(). For more information on what this is doing and why you should use it, please see this question.

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;

public class Test {
  private Timer timer;
  private int count = 0;
  
  public Test() {
    ActionListener taskPerformer = new ActionListener() {
      public void actionPerformed(ActionEvent evt) {
        //What should the timer do?
        count++;
        System.out.println(count);
      }
    }; 
    timer = new Timer(1000, taskPerformer);
    
    JButton start = new JButton("Start");
    start.addActionListener(new ActionListener() {
      @Override
      public void actionPerformed(ActionEvent arg0) {
        if(!timer.isRunning()) {
          System.out.println("Timer started!");
          timer.start();
        } 
      }
    });
    
    JButton stop = new JButton("stop");
    stop.addActionListener(new ActionListener() {
      @Override
      public void actionPerformed(ActionEvent arg0) {
        if(timer.isRunning()) {
          count = 0;
          System.out.println("Timer stopped!");
          timer.stop();
        } 
      }
    });
    
    //Minimal working example 
    JFrame frame = new JFrame("Timer");
    JPanel panel = new JPanel();
    panel.setLayout(new FlowLayout());

    panel.add(start);
    panel.add(stop);
    frame.add(panel);
    
    frame.setSize(300,300);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setVisible(true);
  }
  
  public static void main(String[] args) {
    SwingUtilities.invokeLater(Test::new);
  }
}

nice. I wish my questions were always answered this way. – Conffusion Sep 22 '20 at 12:59 — Conffusion, Sep 22 '20 at 12:59

Start timer (javax.swing) on button-click rather than on its own

1 Answers1