OnClickListener doesn't work implicitly. Why?

Question

I created custom button class that implements listener interface:

public class BlinkButton  extends Button implements View.OnClickListener {

List<OnClickListener> onClickListenerList = new ArrayList<OnClickListener>();

public BlinkButton(Context context) {
    super(context);
    this.setListener(new HighLightButtonListener());
}

//other constructors here 

public void setListener(OnClickListener listener){
    onClickListenerList.add(listener);
}

@Override
public void onClick(View v) {
    for(OnClickListener listener : onClickListenerList){
        listener.onClick(this);
    }
}

And I have view:

   <com.example.element.BlinkButton
    .../>

I claim onClick method inside com.example.element.BlinkButton should call implicitly when user clicks BlinkButton, but it's not. I have to write it explicitly: android:onClick="fireEvent" and

    public void fireEvent(View view) {
        fireEventButton.onClick(view);
    }  

Why BlinkButton.onClick(); doesn't trigger automatically once user clicks button?

Answer 1

Button (or its superclasses) don't have an onClick() method by itself. The one you implement comes from the View.OnClickListener interface your Button class implements.

You never set your class' OnClickListener , and from your code it seems you want the OnClickListener to be the class itself, so your custom Listeners are actually called.

Add this line to the constructor:

setOnClickListener(this);

So it looks like this:

public BlinkButton(Context context) {
    super(context);
    setOnClickListener(this);
    this.setListener(new HighLightButtonListener());
}

You'll also have to remove the onClick xml attribute.

Answer 2

BlinkButton class is only implementing the listener. If you look how View class handles clicks you'll find the following implementation:

public void setOnClickListener(OnClickListener l) {
    if (!isClickable()) {
        setClickable(true);
    }
    getListenerInfo().mOnClickListener = l;
}

Basically there is no way to override a method and get the click events. You can set a listener from your class that will be called on click and that will further send the event to all listeners from your list.

public class BlinkButton extends Button implements View.OnClickListener {

    List<OnClickListener> onClickListenerList = new ArrayList<OnClickListener>();

    public BlinkButton(Context context) {
        super(context);
        this.setListener(new HighLightButtonListener());
        this.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                for (OnClickListener listener : onClickListenerList) {
                    listener.onClick(this);
                }
            }
        };
    }

    //other constructors here 

    public void setListener(OnClickListener listener) {
        onClickListenerList.add(listener);
    }
}