Why is (this) used in setOnClickListener()

Question

Please explain why, in the below code (this) is used as argument to setOnClickListener()? I am new in coding if you could explain the total code I would be thankful.

public class MainActivity extends Appcomatactivity implements 
        View.OnClickListner {

  Textview textview;
  Button push_me, push_me2;

  protected void onCreate(bundle savedInstance) {
    super.onCreate(savedInstance);
    setContentView(R.Layout.activity_main);
    textview = (Textview)findViewById(R.Id.Textview);
    push_me=(Button)findViewById(R.Id.pushmebutton);
    push_me2=(Button)findViewById(R.Id.pushmebutton2);

    // Why does below code use (this) as argument?
    push_me.setOnClickListener(this);
    push_me2.setOnClickListener(this);
  }
  // <...some activity methods...>

  // onclick method defined:
  public void onClick(View view) {
    switch(view.getid()) {
      case R.Id.pushmebutton:
        textview.setText("button 1 clicked");
        break;
      case R.id.pushmebutton2:
        textview.setText("button 2 clicked");
        break;
    }
  }
}

This will Help: https://stackoverflow.com/questions/29479647/setonclicklistener-vs-onclicklistener-vs-view-onclicklistener — Aj 27, Apr 04 '18 at 08:48
By implementing `View.OnClickListener` you are saying that `MainActivity` class can react to `click` events on some component. To make it do so, you have to register the `MainActivity` instance with the view, which is done by setting it into a View using that method. — M. Prokhorov, Apr 04 '18 at 11:55

score 3 · Answer 1 · edited Apr 04 '18 at 11:30

3

Why is (this) used in setonclicklistner

Because your have implemented View.OnClickListener interface to your activity

View.OnClickListener Interface definition for a callback to be invoked when a view is clicked.

By using this push_me.setOnClickListener(this); you have registered click listener to your view

edited Apr 04 '18 at 11:30

Nilabja

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answered Apr 04 '18 at 09:04

AskNilesh

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score 1 · Answer 2 · answered Apr 04 '18 at 12:15

when we don't want to use anonymous class then we use this other way is to use anonymous inner class

//declaring OnClickListener as an object
private OnClickListener btnClick = new OnClickListener() {
@Override
public void onClick(View v) {
    // TODO Auto-generated method stub
}
};
//passing listener object to button
btn1.setOnClickListener(btnClick);

If there are multiple buttons which require same code to be executed on onClick event then you may define listener as an object and pass it to them.

Why is (this) used in setOnClickListener()

2 Answers2