Passing the View class object as a parameter to the method invoked by a button (View view)

Question

I'm trying to create an app for Android, and I follow this tutorial http://developer.android.com/training/basics/firstapp/starting-activity.html

there is a part

/** Called when the user clicks the Send button */
public void sendMessage(View view) {
    // Do something in response to button
}

then I followed this tutorial and everything worked, untill I remove parameter View view

my question is just why everytime I remove it, so the function just be:

/** Called when the user clicks the Send button */
public void sendMessage() {
    // Do something in response to button
}

and I run the app, it forced close.

could anyone enlighten me? thank you

Answer 1

When you put this kind of thing in your xml :

android:onClick="sendMessage" 

The android framework will add an OnClickListener on your button. This "automatically" generated OnclickListener will try to call a method named "sendMessage" with one single argument of type View.

If this method doesn't exists it simply crash.