How to change icon in JLabel with JButton

Question

I'm making a simple conversion tool to convert dollars to euro's and vice versa.

The whole purpose is just to experiment and learn this cool tool, java.

I have a JLabel at the top with an icon of a euro to indicate the starting currency. I have a button bellow this that I want to use to change that icon to a dollar one.

I am currently plying around with an ActionListener and trying different variations of setIcon/setIconImage (every itteration I can think of seeing that nothing has worked thus far).

---

public class MoneyConverter extends JFrame implements ActionListener{
     //add label and icon showing base conversion currency
     JLabel startcur = new JLabel("<--- Starting Curency", new ImageIcon("C:\\Users\\Russel\\Desktop\\1euro.gif"), SwingConstants.CENTER);
     JButton euro = new JButton("Swap to Euro");
     JButton dollar = new JButton("Swap to Dollar");

---

I then set up a

public MoneyConverter(){} 

method and add all my components to a grid layout and add ActionLister's to my convert buttons.

eg

    dollar.addActionListener(this);
    euro.addActionListener(this);

After the usual code (setVisible and the likes that I will omit for your sake as I don't see it interfering with this, please let me know if I should include it all)

public void ActionPerformed (ActionEvent e){
    Object source = e.getSource();
    if (source.equals(euro)){
         startcur.setIcon(new ImageIcon("C:\\Users\\Russel\\Desktop\\1.gif"));
    }
}

This part has been changed many times and is the main reason for this post, how do I change this icon in the JLabel? - I will also be setting the conversion rate in here depending if they choose to start with dollars or euros. (Rate won't be actual rate.)

Answer 1

First, create and store a new ImageIcon

ImageIcon image = new ImageIcon(getClass().getResource("/nameOfImage.jpg"));

Then put this in your Action Listener

label.setIcon(image);
label.setText("");

You have to make sure you have a resource folder set up for your project. You can read how to do that in IntelliJ or Eclipse

You are also declaring the actionPerformed() wrong. I suggest reading up on this You should be doing it like this.

@Override
public void actionPerformed(ActionEvent e)
{

}

Conventionally, in java, method names start with a lower case letter and Classes start with an upper case.

Answer 2

The whole purpose is just to experiment and learn this cool tool, java.

Then I'll show you how to improve this program in a number of ways.

//Don't make your Swing class implement Actionlistener and add it as a
//listener to itself in the constructor before it's fully initialized
public class MoneyConverter extends JFrame {
    //These don't have to be loaded at runtime, so make them into constants
    //Java variables and methods follow thisNamingConvention
    private static final Icon euroIcon = new ImageIcon("C:\\Users\\Russel\\Desktop\\1euro.gif");
    private static final Icon dollarIcon = new ImageIcon("C:\\Users\\Russel\\Desktop\\1dollar.gif");
    //These you probably want to use later so save them as private class variables
    //Make them final so you can access them in the ActionListeners below
    private final JLabel currencyLabel;
    private final JButton euroButton;
    private final JButton dollarButton;

    public MoneyConverter() {
        //These are declared final and are are therefore usually set first in constructor
        this.currencyLabel = new JLabel("<--- Starting Curency", euroIcon, SwingConstants.CENTER);
        this.euroButton = new JButton("Swap to Euro");
        this.dollarButton = new JButton("Swap to Dollar");

        //Write your own separate ActionListener for each button
        euroButton.addActionListener(new ActionListener() {
            @Override
            public void run() {
                currencyLabel.setIcon(euroIcon);
                //These two are required for you to see the effect
                //This should also be the solution to your initial problem
                currencyLabel.revalidate();
                currencyLabel.repaint();
            }
        });
        dollarButton.addActionListener(new ActionListener() {
            @Override
            public void run() {
                currencyLabel.setIcon(dollarIcon);
                currencyLabel.revalidate();
                currencyLabel.repaint();
            }
        });

        //Add your components here using whatever layout manager you want.
    }

    public static void main(String []args){
        //Start new Swing applications like this to prevent it from
        //clogging the rest of the program
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new MoneyConverter();
            }
        });
    }
}