Android Toast

//Program  1

import android.widget.*;  //1

import android.view.*;   //2

import android.view.View.OnClickListener;//3

public class MainActivity extends Activity {

Button b1;   //4

            @Override

            protected void onCreate(Bundle savedInstanceState) {

                        super.onCreate(savedInstanceState);

                        setContentView(R.layout.activity_main);

                        b1=(Button) findViewById(R.id.button1); //5

                        b1.setOnClickListener(s1); //6

            }

public OnClickListener s1=new OnClickListener()

    {

            public void onClick(View v)

            {

                        if(v==b1)

                        {

    Toast.makeText(getApplicationContext(), "welcome", Toast.LENGTH_SHORT).show();

                        }

            }

    };

}