ViewOnClickListener.java

public class MyActivity extends Activity implements View.OnClickListener {

    Button button1, button2, button3;

    @Override
    public void onCreate(Bundle bundle) {
        super.onCreate();
        /.../
        button1 = (Button) findViewById(R.id.button1);
        button2 = (Button) findViewById(R.id.button2);
        button3 = (Button) findViewById(R.id.button3);

        button1.setOnClickListener(this);
        button2.setOnClickListener(this);
        button3.setOnClickListener(this);
   }

   @Override
   public void onClick(View v) {
       switch(v.getId()) {
           case R.id.button1:
           // do stuff;
           break;
           case R.id.button2:
           // do stuff;
           break;
       /.../
   }
}