Advantage and advantage between onClick and setOnClickListener

Question

I have a certain situation where we see that it is possible to create in the XML file a property called onClick:

onClick:

XML:

<Button
android:layout_height="@dimen/edittext_min_height"
android:layout_alignParentLeft="true"
android:minWidth="120sp"
android:onClick="btnSend"
android:clickable="true"/>

Class:

public void btnSend(View view){
    //faça algo
}

---

On the other hand we can also instantiate within the class the setOnClickListener():

setOnClickListener:

XML

<Button
    android:id="@+id/btnSend"
    android:layout_height="@dimen/edittext_min_height"
    android:layout_alignParentLeft="true"
    android:minWidth="120sp"/>

Class:

Button btnSend = (Button) findViewById(R.id.btnSend);
btnSend .setOnClickListener(new OnClickListener() {
   @Override
   public void onClick(View v) {
      //faça algo
   }
});

What would be the advantages and disadvantages between using onClick and setOnClickListener?

Answer 1

I find only one advantage in each of them which, in turn, represent a disadvantage in relation to the other.

setOnClickListener().

• Upside.
  Allows reuse of existing code.
  If you implement the interface in a separate class it can be reused in other similar situations.
• Downside.
  The implementation, being done in an anonymous class, makes the code more difficult to read and maintain. Of course it is debatable and some say otherwise. In my opinion it is code that "appears out of nowhere", in the middle of the one in which I am interested to read/analyze.

onClickin XML

• Upside.
  Easier to read code. The code is in a method declared for this purpose.
  Can avoid the need to have a field and use the findViewById()
• Downside.
  Code cannot be reused.
  It only works when the view is used in an Activity.

For simple implementations and without the need for code to be reused, use the onClick in XML with the respective java method.
For more complex implementations and/or code reuse, create a separate class and use the setOnClickListener().

Answer 2

I believe there is only one difference or different mode of application. The methods are similar, whether you indicate your action by clicking the button on XML how to handle this action by Listener.

It turns out that by using the android:onClick the method setOnClickListener is implementing it the same way, only you don’t see it. They do the same thing. And yes, you can handle several different actions using the XML.

Take an example:

XML

<Button android:id="@+id/b_1"
    android:onClick="actionHandle"/>

<Button android:id="@+id/b_2"
    android:onClick="actionHandle"/>

Java

public void actionHandle(View v){
    switch(v.getId()){
        case R.id.b_1:
            // act!
            break;

        case R.id.b_2:
            // act!
            break;
    }
}

See that you can use the method actionHandle or any method you define, to handle the click that occur in your botões. If you are going to use the setOnClickListener, would look something like this:

setOnClickListener

public class A extends Activity {

    @Override
    protected void onCreate(Bundle b){
        super.onCreate(b);
        // setContent

        (findViewById(R.id.b_1)).setOnClickListener(actionHandle);
        (findViewById(R.id.b_2)).setOnClickListener(actionHandle);
    }

    View.OnClickListener actionHandle= new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            switch (v.getId()){
                case R.id.b_1:

                    break;

                case R.id.b_2:

                    break;
            }
        }
    };
}

In my opinion, use the attribute in XML is more malleable and organized and, of course, if you know how to use the attribute without creating several methods for different buttons, use the android:OnClick is the best option no matter the size of the application.

Answer 3

I had the same doubt and I deepened the subject and then of that answer I ended up convincing myself not to use onClick. Basically: the implementations of Android buttons indicate that the button will be clickable, however, if any manufacturer arrow it to false, you will only feel the problem through the market. You can force the button to be clickable, but if you forget, a hug!

EDIT: From what I identified in the answer, the problem is in setting the event Click on a non-button object.

Answer 4

There is no more correct way.

But the second option setOnClickListener in activity is recommended as good practice. For having a faster view of the function that the method has. To perform a maintenance, or even during development, the use of the onClick in XML, may end up generating more confusing code.