Re: Button event

From:
"nblloyd@gmail.com" <nblloyd@gmail.com>
Newsgroups:
comp.lang.java.gui
Date:
29 Jun 2006 08:13:31 -0700
Message-ID:
<1151594011.887720.156110@y41g2000cwy.googlegroups.com>
You can also write a generic action listener which will invoke a method
on an object:

public class GenericActionListener implements ActionListener {

    protected Method method;
    protected Object object;

    public GenericActionListener(Object object, String methodName) {
        this.object = object;
        try {
            method = object.getClass().getMethod(methodName, null);
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        }
    }

    // this invokes the method
    public void actionPerformed(ActionEvent e) {
        try {
            method.invoke(object, null);
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }
    }
}

So, if you have a controller class (say, GUIController), create methods
like "save", "open", "close", etc. in it:

public class GUIController {
    ...
    public void save() {
        ...
    }
    ...
}

Then, for your buttons, simply do this:

// assuming you have a variable for the GUIController called
"guiController"
// (or you can use "this" if your GUI is itself the controller
JButton saveButton = new JButton(...);
saveButton.addActionListener(new GenericActionListener(guiController,
"save"));

When the button is clicked, the method guiController.save() will be
invoked. It's a nice way to keep your code clean, IMO.

You can also extend GenericActionListener to use methods that have
arguments. I'm just showing the bare bones.

- Natasha -

jaap wrote:

Hello

I'm a real noob with java. I worked for 4 years with php but now I have
to use java.
I'm looking for a clean way to get an action behind a button/menuitem. I
  already found the class actionListener. but the method actionpreformed
is not very clean if you want to give 20 buttons an action. The way I
know is 20 times else if. There must be an better method.

I will try to use my GUI like an interface. It does'nt have to include
much code in my opinion. I think it have to be only some field and
button delcarations.

thx for your help

greetz
Jaap

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