how to sterart a new activity by click of a button in andriod code example

Example 1: intent android open activity

Intent intent = new Intent(this, DisplayMessageActivity.class);
        intent.putExtra(key:,value:);
        startActivity(intent);

Example 2: android how to start a new activity on button click

Intent intent = new Intent(this, ActivityToBeCalled.class);
startActivity(intent);