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Adding a action listener in java for a counter

I am a fairly new user with programming in Java with about a week and a bit experience, as of before I have been using python for about 3 years but thought to give java a try.
I have been trying to develop my skills by creating small projects and applications and am now creating a small GUI counter.
I have achieved creating the GUI with 2 buttons and a label and have tested the maths behind the application but I am struggling to work out how the ActionListener works as it feels a lot different to python when making a button have a action.
This is My Code;
package gui;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Frame;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.*;
public class GUI{
//This creates a frame or panel to contain things
public static void main(String[] args) {
//Maths To The Counter
int Counter = 0;
System.out.println(Counter);
Counter =+ 1;
System.out.println(Counter);
//Creating The Frame
JFrame frame = new JFrame();
JPanel panel = new JPanel();
panel.setBackground(Color.WHITE);
frame.getContentPane().add(panel);
//Creating The Label
JLabel label3 = new JLabel("Counter: ");
panel.add(label3);
//Button Which should have a funtion to add and display the number
JButton button = new JButton("Click Here.");
panel.add(button);
//Button to reset the counter
JButton buttonReset = new JButton("Reset Counter.");
panel.add(buttonReset);
//Set Size Of Window
frame.setSize(new Dimension(500, 400));
//Set Starting Position to centre
frame.setLocationRelativeTo(null);
//Setting a default close action
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Set Title
frame.setTitle("Counter");
//Disable Resize
frame.setResizable(false);
//Setting if its visible
frame.setVisible(true);
//Fits frame to fit everything
frame.pack();
}
}
enter code here
I know that in python a action is in a function so that has been my logic to this problem however I have seen that I need to use the actionlistener instead and I am struggling to get my head around it.
If Someone could show me how this type of action should be implemented it would be great help, I have watch some youtube videos and done a bit of research but im still struggling to understand in my situation how to do it.
For any confussion im sorry, overall my question is how do I add a action to a button in my program that can implement my maths at the start.
As well any feedback on the structure of my code would be welcomed as I am just starting in java and I do know poor structure can lead to mistakes.

This code should work:
Basically, in the main method I am creating an instance of the class and calling a method to create the gui.
I also created an instance variable as the counter, otherwise you won't be able to update the variable in your action listener.
public class Gui {
private int counter;
// This creates a frame or panel to contain things
public static void main(String[] args) {
Gui gui = new Gui();
gui.create();
}
private void create() {
// Creating The Frame
JFrame frame = new JFrame();
JPanel panel = new JPanel();
panel.setBackground(Color.WHITE);
frame.getContentPane().add(panel);
// Creating The Label
JLabel label3 = new JLabel("Counter: ");
panel.add(label3);
// Button Which should have a funtion to add and display the number
JButton button = new JButton("Click Here.");
panel.add(button);
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
System.out.println(counter++);
}
});
// Button to reset the counter
JButton buttonReset = new JButton("Reset Counter.");
panel.add(buttonReset);
buttonReset.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
counter = 0;
}
});
// Set Size Of Window
frame.setSize(new Dimension(500, 400));
// Set Starting Position to centre
frame.setLocationRelativeTo(null);
// Setting a default close action
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Set Title
frame.setTitle("Counter");
// Disable Resize
frame.setResizable(false);
// Setting if its visible
frame.setVisible(true);
// Fits frame to fit everything
}
}
With Lambda expressions, you can simplify your action listeners as follows:
button.addActionListener(a -> System.out.println(counter++));
buttonReset.addActionListener(a -> counter = 0);
If you want to write more than 1 statement, then you can just put your code in curly brackets:
button.addActionListener(a -> {
System.out.println(counter++);
System.out.println("doing more stuff...");
});

JButton has a function called addActionListener. You can pass on an action listener by doing this:
button.addActionListener(() -> {
// Do some logic here
});
Here, I use a lambda expression as an action listener. Within the lambda expression you can place whatever logic you want to have.
Also note that you can add multiple different action listeners to the same button. In a nutshell, the way the JButton interacts with the ActionListeners is based on the observer-pattern.
Imagine this: When the JButton is pressed, it will notify all of it's observers saying "Hey, I have been pressed". Each observer can then independently decide what to do. In case of the JButton, all observers are ActionListeners. If you add multiple ActionListeners then the JButton will notify all of them, and as a result all of their actionPerformed(ActionEvent e) functions are executed. In the example above, I used a lambda expression which then by java is interpreted as an ActionListener.
Other ways to achieve the exact same functionality are:
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
// Do some logic here
}
});
In the example above, you use an anonymous class as an actionlistener.
public class MyClass {
public MyClass() {
JButton button = new JButton("press me");
button.addActionListener(new MyActionListener());
}
private class MyActionListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
// Do some logic here
}
}
}
In the example above, an inner class is used.
In a nutshell, there is a ton of ways you can make your button have functionality. Above are just a few examples of how to do so.
Does this clarify it a bit more, or do you have some remaining questions?

Why does using ActionListener break my Swing Applet?

I have an application working in Java Swing, but can't seem to convert to an Applet. Basically there are four buttons displayed on the Applet, and I want one of them to clear the screen and then draw a new interface (I'm going to add stuff for the other buttons, of course, but I got stuck here).
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.JApplet; //import swing applet interface
import java.util.Hashtable;
public class TopMenu extends JApplet{
private JPanel panel = new JPanel();
public void init(){
mainMenu();
}
public void mainMenu() {
// create buttons
panel.setLayout(new GridLayout(2, 2));
JButton collectButton = new JButton("Collect data");
JButton uploadButton = new JButton("Upload");
JButton downloadButton = new JButton("Download");
JButton exploreButton = new JButton("Explore data");
panel.add(collectButton);
panel.add(uploadButton);
panel.add(downloadButton);
panel.add(exploreButton);
collectButton.addActionListener(new ActionListener( ) {
public void actionPerformed(ActionEvent e) {
int numberGFish = 400;
//panel.removeAll();
//panel.add(new JLabel("Just to test"), BorderLayout.CENTER);
//panel.revalidate();
//panel.repaint();
}
});
setContentPane(panel);
}
}
All the code works totally fine until I add the ActionListener, and then the whole thing just goes blank. It compiles okay, but when I test it on my server not even the first menu comes up, it's just a blank panel. I've tried putting loads of really banal things in the ActionListener bit to make sure it's not a problem with them, but as you can see even just declaring a number in there doesn't work.
Originally I actually had the Listener bit call on another method which then did everything else, and that didn't work either, I scrapped that because I thought perhaps that was the problem.
I'm sure this is so simple but I've sunk many hours into it now and I've really just run out of ideas of things to test. And advice gratefully appreciated.

Don't know if it would be a problem or not but all GUI components should be created on the Event Dispatch Thread.
Here is the recommended code structure from the Swing tutorial on How to Make Applets:
public void init() {
//Execute a job on the event-dispatching thread:
//creating this applet's GUI.
try {
javax.swing.SwingUtilities.invokeAndWait(new Runnable() {
public void run() {
createGUI();
}
});
} catch (Exception e) {
System.err.println("createGUI didn't successfully complete");
}
}
private void createGUI() {
JLabel label = new JLabel(
"You are successfully running a Swing applet!");
label.setHorizontalAlignment(JLabel.CENTER);
label.setBorder(BorderFactory.createMatteBorder(1,1,1,1,Color.black));
add(label, BorderLayout.CENTER);
}

I knew it was a dumb question, but I just couldn't figure it out. I've sorted it now.
I was being totally daft and not copying across the TopMenu$1.class file to the server. For some reason it works without this file but not with the ActionListener bit added. So I never thought that could be the problem.
Doh! Thanks all.

How can I prevent my JFrame Window from multiplying?

For the sake of everyone understanding my problem, I've created a simple GUI program which shows my problem. I'll first put the codes for you to analyze. And then, please watch the video below to see what I've been meaning to ask. Please bear with me, the video is just a few seconds and will not take time to load.
Menu JFrame:
//This is a Menu JFrame Window
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
public class Menu extends JFrame implements GlobalVariables{
public Menu(){
clickMe.setBounds(75, 50, 100, 50);
clickMe.addActionListener(new ActionListener(){
#Override
public void actionPerformed(ActionEvent e){
dispose();
SubMenu sm = new SubMenu();
sm.subMenuProperties();
}
});
add(clickMe);
}
void menuProperties(){
setLayout(null);
setSize(250,175);
setVisible(true);
setResizable(false);
setLocationRelativeTo(null);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String[] args) {
Menu m = new Menu();
m.menuProperties();
}
}
SubMenu JFrame:
//This is a SubMenu JFrame Window
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
public class SubMenu extends JFrame implements GlobalVariables{
public SubMenu(){
clickMe2.setBounds(75, 50, 100, 50);
clickMe2.addActionListener(new ActionListener(){
#Override
public void actionPerformed(ActionEvent e){
dispose();
Menu m = new Menu();
m.menuProperties();
}
});
add(clickMe2);
}
void subMenuProperties(){
setLayout(null);
setSize(250,175);
setVisible(true);
setResizable(false);
setLocationRelativeTo(null);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String[] args) {
SubMenu sm = new SubMenu();
sm.subMenuProperties();
}
}
And if your're wondering what's the "GlobalVariables" implementation, here it is:
import javax.swing.*;
public interface GlobalVariables{
//Menu Variable
JButton clickMe = new JButton("SubMenu");
//SubMenu Variable
JButton clickMe2 = new JButton("Back");
}
Now, this video will show you what I mean in JFrame being multiplied:
http://www.youtube.com/watch?v=iCavg_1SqvY
*If you watched the video, you can see what I mean when I say the JFrame is being multiplied. I've been analyzing this for days but I cannot identify my mistake. If you can just pinpoint my mistake, I'll be more than thankful. I'm also open for comments and adjustments in the code, I just wish that the structure of the code will not be re-structured because as I've said earlier, I've created this simple GUI just to show you my problem but to tell you at least, I have a whole program waiting to be finished using this kind of approach in GUI making. Please help me.

Those two classes are both a subclass of JFrame which results in a new window.
The one named Menu contains a button "clickMe" which instantiates SubMenu that contains a button "clickMe2" that instantiates Menu. This creates a endless loop creating more instances of each class. I.e creating more frames.
In the class SubMenu, remove these lines:
Menu m = new Menu();
m.menuProperties();
To get started using swing, Oracle has great tutorials.

I found the issue with the code. You need to remove the ActionListener in you actionPerformed method. For each button click, your code creates a new ActionListener object and it gets associated with your button. Subsequent clicks gets executed by this duplicate action listeners and you end up getting more JFrames.
Add the below line to actionPerformed(ActionEvent e) method of both classes after the line dispose(). This should fix your problem
Menu.java
clickMe.removeActionListener(this);
......
SubMenu.java
clickMe2.removeActionListener(this)
;

Java, NetBeans IDE and JTextField

it's a shame that my first question on SO is so stupid but i can't manage to get around this thing.
After hours of "distilling" i have reduced the issue to this:
Using Netbeans i've made a JFrame, and put a Jbutton1 and a JTextField(named sinonimo) in it.
The idea is to use the text field to grab user input. so i set the onClick action of the button like this
private void jButton1MouseClicked(java.awt.event.MouseEvent evt) {
System.out.println(sinonimo.getText());
}
Problem is: i can type anything in the text field, the getText() method will return only the string set in the "text" properties in Netbeans, it will never change.
Am i missing something huge about java? can someone point me in the right direction?
EDIT: while copying the complete code i found the problem: in the constructor of the frame, initComponents() was called two times, generating another copy of the textfield inaccessible from the MouseClicked event(i think). Now everything seem to work nicely, thank you guys for the lighting responses!

Using a JTextField, if you call getText() it will return null should the index be out of range or the Document is null. If you could post more code I could help further with this issue. With the following code this works perfectly fine.
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class Test {
public static void main(final String[] args) {
final JFrame frame = new JFrame();
final JButton button = new JButton("Print");
final JTextField field = new JTextField();
frame.setLayout(new BorderLayout());
frame.add(button, BorderLayout.NORTH);
frame.add(field, BorderLayout.SOUTH);
frame.setVisible(true);
frame.pack();
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
System.out.println(field.getText());
}
});
}
}
From what I can see, until you post more code, is that either the method you print it from is not being used, the document is returning null or that the sinonimo instance was not added correctly and doesn't function how it should.

I have a JLabel that doesn't want to update

I've looked at other JLabel threads and though similar, a few just don't seem to apply to what I'm experiencing. First, I want to say I am a novice when it comes to Java. Next, I am trying to follow tutorials and demos at the docs.oracle.com site. Now, I can update the label when I type something into a JTextField and there is an ActionListener on that...
But I also have a Menu, and when I select a Menu Item, that Action does not want to update the label.
Questions -
How do I have action listeners on both JTextFields and JMenuItems? Are there two ActionEvent methods or do I use one method and somehow identify each type of action?
If I use the same basic code in the JTextField ActionEvent and JMenuItem ActionEvent, the JLabel updates correctly with the JTextField event but not JMenuItem event. They both use the messageField.setText property. Could the JMenuItem action be doing something to block the setText?
I can easily copy code in here, but it's pretty spaghetti-like at the moment, so if you want to see anything, let me know specifically and I'll post it.
I would appreciate any assistance that anyone would be able to provide.
---edit---
Wow!! Thanks for all of the comments and suggestions.
1 - I know it has to be my code. As I mentioned, I am really just cobbling stuff together from demos and tutorials, and trying to learn Java along the way. I've just never gotten the hang of object oriented....
2 - I do know the individual Listeners are working. I'm using System.out.println to validate, as well as inspecting those labels in debug mode to see they have indeed changed.
3 - I will look at the various links and code posted here and see if I can figure out what's wrong with my code.
Really, thanks again!
---edit---
Here is what I originally had in my createAndShowGUI method....
private static void createAndShowGUI()
{
JFrame frame = new JFrame("Create XML for Photo Gallery");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
CreateGalleryXML window = new CreateGalleryXML();
frame.setJMenuBar(window.createMenuBar());
frame.add(new CreateGalleryXML());
frame.pack();
frame.setVisible(true);
}

Seems like you yourself are doing something wrong, in your code. Without a proper SSCCE it's hard to say what thing you doing wrong, since it works perfectly, using same ActionListener for both JMenuItem and JTextField.
Here is a sample program to match with yours :
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class UpdateLabel
{
private JLabel label;
private String labelText;
private ActionListener action = new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
setLabelText((String) ae.getActionCommand());
label.setText(getLabelText());
}
};
private void setLabelText(String text)
{
labelText = text;
}
private String getLabelText()
{
return labelText;
}
private void createAndDisplayGUI()
{
final JFrame frame = new JFrame("Update Label");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setLocationByPlatform(true);
JMenuBar menuBar = new JMenuBar();
JMenu programMenu = new JMenu("Program");
JMenuItem exitMenuItem = new JMenuItem("Exit");
exitMenuItem.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
frame.dispose();
}
});
JMenu labelMenu = new JMenu("Label");
JMenuItem updateMenuItem = new JMenuItem("Update Label");
updateMenuItem.setActionCommand("Updated by JMenuItem");
updateMenuItem.addActionListener(action);
programMenu.add(exitMenuItem);
labelMenu.add(updateMenuItem);
menuBar.add(programMenu);
menuBar.add(labelMenu);
frame.setJMenuBar(menuBar);
JPanel contentPane = new JPanel();
label = new JLabel("I am the LABEL which will be updated!!");
contentPane.add(label);
JTextField tfield = new JTextField(10);
tfield.setActionCommand("Updated by JTextField");
tfield.addActionListener(action);
frame.add(contentPane, BorderLayout.CENTER);
frame.add(tfield, BorderLayout.PAGE_END);
frame.pack();
frame.setVisible(true);
}
public static void main(String... args)
{
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
new UpdateLabel().createAndDisplayGUI();
}
});
}
}
And here is the output in both the cases :
and
Do check out the main method, might be you had failed to put your code inside EDT - Event Dispatcher Thread, that can lead to such issues too. All updates on the Swing GUI, must be done on the Event Dispatcher Thread.
LATEST EDIT
It seems to me that CreateGalleryXML extends JPanel by the look of it. See at Line 3 of this below code taken from your update, here you are initializing a new Object of CreateGalleryXML inside, when you already had one Object window created at Line 1:
CreateGalleryXML window = new CreateGalleryXML();
frame.setJMenuBar(window.createMenuBar());
frame.add(new CreateGalleryXML());
So try to change the above thingy to this
CreateGalleryXML window = new CreateGalleryXML();
frame.setJMenuBar(window.createMenuBar());
frame.add(window);
and see what happens and Please do revert back again :-)

Use Action to encapsulate common functionality that must be shared by menus and related components. See this example that extends AbstractAction.

Pretty much everything you could need to know is in the Java tutorials. Down the bottom they have demo's on how to do both menu's and text fields. They include source code to look at as well.
There's not much more I can say that they don't say better, but in answer to your questions:
Both, you can have separate listener's on each component, or one that figures out what component is responsible for causing the action event. I would suggest you use separate ones for each thing.
Can't really say with out seeing the code, are you sure that the action on the JMenu is even firing? Does it print something to the console etc if you use System.out.println somewhere?