Android Programs(Add two numbers)

import android.widget.*;

import android.view.*;

import android.view.View.OnClickListener;

public class MainActivity extends Activity {

Button b1;

EditText t1,t2,t3;

            @Override

            protected void onCreate(Bundle savedInstanceState) {

                        super.onCreate(savedInstanceState);

                        setContentView(R.layout.activity_main);

                        t1=(EditText) findViewById(R.id.editText1);

                        t2=(EditText) findViewById(R.id.editText2);

                        t3=(EditText) findViewById(R.id.editText3);

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

                        b1.setOnClickListener(s1);

            }

public OnClickListener s1=new OnClickListener()

{

   public void onClick(View v){

               if(v==b1){

               int a=Integer.parseInt(t1.getText().toString());

               int b=Integer.parseInt(t2.getText().toString());

               int c=a+b;

               t3.setText(String.valueOf(c));

 Toast.makeText(getApplicationContext(),String.valueOf(c), Toast.LENGTH_SHORT).show();

               }

   }

};

}