[Android] setOnClickListener

@Override
protected void onCreate(Bundle savedInstanceState) {  

  //type1
 ib_goback = (Button) findViewById(R.id.ib_goback);
 ib_goback.setOnClickListener(new OnClickListener() {
  @Override
  public void onClick(View v) {
   Intent intent = new Intent(Login.this, BeginAdvertisement.class);
   startActivity(intent);
   Login.this.finish();
  }  
 }); 
  
 //type2
 con = (Button) findViewById(R.id.btn_CON);
 Buttonclick btnclick = new Buttonclick();
 con.setOnClickListener(btnclick);
}

//type2
class Buttonclick implements Button.OnClickListener {

 @Override
 public void onClick(View v) {
  // TODO Auto-generated method stub

  switch (v.getId()) {
  case R.id.btn_CON:

   break;

  default:
   break;
  }
 }
}