Question

My question is specific to Eclipse and the Swing WindowBuilder plugin.

To make simple Swing apps I normally create a class and extend a JFrame. I make my Swing components private class variables. This allows me to add an Actionlisteners and access the swing components in actionPerformed(), like this:

public class MyClass() extends JFrame implements ActionListener {
    private JButton btnClickMe = new JButton("Click me");

    public MyClass() {
        super("title");
        this.setLayout(null);
        btnClickMe.setBounds(1,1,100,100);
        this.add(btnClickMe);
        btnClickMe.addActionListener(this);
        this.setVisible(true);
    }

    public void actionPerformed(ActionEvent event) {
        Object source = event.getSource();
        if(source == btnClickMe) { // do something }
    }

    public static void main(String[] args) {
        new MyClass();
    }
}

By default the WindowBuilder plugin create Swing component variables I guess in what would be considered the constructor (public MyClass()), rather than private class variables. As a result due to scope I am not able to use ActionListeners the way I am used to since the Swing variables are not visible to actionPerformed().

Can anyone advise how this can be overcome?

Answer 1

What’s stopping you from refactoring those local variables to fields? One of the best things about WindowBuilder is able to parse hand written code to some extent.

Besides, there’s a configuration option in Window Builder to create field variables for controls. Look in Eclipse, Preferences->WindowBuilder->Swing->Code generation 😉