Android - setOnClickListener vs OnClickListener vs View.OnClickListener

Question

My understanding is that when I'm creating a button object that listens for a click, I have to:

1. Create the button object
2. Use OnClickListner to make it listen to the user's click
3. Use onClick to execute actions after the user clicks the button

Now,

• Where does setOnClickListener fit into the above logic?
• Which one actually listens to the button click?
• setOnClickListener?
• OnClickListener?
• View.OnClickListener?
• What are the differences between those three?

Here is what I found in Android Dev:

//The example below shows how to register an on-click listener for a Button.

// Create an anonymous implementation of OnClickListener
private OnClickListener mCorkyListener = new OnClickListener() {
    public void onClick(View v) {
      // do something when the button is clicked
    }
};

protected void onCreate(Bundle savedValues) {
    ...
    // Capture our button from layout
    Button button = (Button)findViewById(R.id.corky);
    // Register the onClick listener with the implementation above
    button.setOnClickListener(mCorkyListener);
    ...
}

You may also find it more convenient to implement OnClickListener as a part of your Activity. This will avoid the extra class load and object allocations. For example:

public class ExampleActivity extends Activity implements OnClickListener {
    protected void onCreate(Bundle savedValues) {
        ...
         Button button = (Button)findViewById(R.id.corky);
         button.setOnClickListener(this);
    }

    // Implement the OnClickListener callback
    public void onClick(View v) {
      // do something when the button is clicked
    }
}

question from:https://stackoverflow.com/questions/29479647/android-setonclicklistener-vs-onclicklistener-vs-view-onclicklistener

Answer 1

The logic is simple. setOnClickListener belongs to step 2.

1. You create the button
2. You create an instance of OnClickListener* like it's done in that example and override the onClick-method.
3. You assign that OnClickListener to that button using btn.setOnClickListener(myOnClickListener); in your fragments/activities onCreate-method.
4. When the user clicks the button, the onClick function of the assigned OnClickListener is called.

*If you import android.view.View; you use View.OnClickListener. If you import android.view.View.*; or import android.view.View.OnClickListener; you use OnClickListener as far as I get it.

Another way is to let you activity/fragment inherit from OnClickListener. This way you assign your fragment/activity as the listener for your button and implement onClick as a member-function.