public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
      
        //Creating Button variable
        Button button = (Button) findViewById(R.id.bt);     
      
       //Adding Listener to button
         button.setOnClickListener(new View.OnClickListener() {
          
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
              
                //Creating TextView Variable
                TextView text = (TextView) findViewById(R.id.tv);
              
                //Sets the new text to TextView (runtime click event)
                text.setText("hello welcum");
                
            }
            
        });
  
    }