There are two ways that button implements onclicklistener events in Android

 
package com.demos; 
import android.app.Activity; 
import android.os.Bundle; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
public class GetScreenActivity extends Activity { 
private Button firstBtn = null; 
private Button secBtn = null; 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
super.onCreate(savedInstanceState); 
setContentView(R.layout.main); 
firstBtn = (Button) findViewById(R.id.firstBtn); 
secBtn = (Button) findViewById(R.id.secBtn); 
firstBtn.setOnClickListener(listener); 
secBtn.setOnClickListener(new OnClickListener() { 
@Override 
public void onClick(View v) { 
// TODO Auto-generated method stub 
} 
}); 
} 
private OnClickListener listener = new OnClickListener(){ 
@Override 
public void onClick(View view) { 
} 
}; 
}