How to get data for first activity and to use that data in second activity?

Question

I am using 2 activities , when i click the button on the first activity it goes to the second activity but how to get data from first activity and do some calculations , display the obtained results in the second activity? Help me I am stuck.!

Answer 1

    Intent intent = new Intent(FirstActivity, DetailActivity.class);
    intent.putExtra("thingtoPass", itemId);
    startActivity(intent);

Answer 2

In Your First Activity

Intent intent = new Intent(this, SecondActivity.class);   
String message = "hello";
intent.putExtra(EXTRA_MESSAGE, message);
startActivity(intent);

In Your second Activity

Intent intent = getIntent();
String message = intent.getStringExtra(FirstActivity.EXTRA_MESSAGE);