How to transfer string data from main activity to another Activity

Question

I need to make a Fragment (Dialog Box, whatever) with content that changes depending on what the user selects. This means that I need to transfer string data from my main activity to the activity responsible for the fragment. How do I do this?

Answer 1

You can add extras to an Intent you use when starting an activity from inside of another.

So, for example, wherever you handle the users selection in the first Activity (Let's call it Activity A) you can send that string to Activity B like this:

Intent intent = new Intent(ActivityA.this, ActivityB.class);
intent.putExtra("stringKey", "stringValue");
startActivity(intent);

The first parameter is a key used to reference the extra that you need, and the value is whatever String you want passed to the next activity.

Then, somewhere in Activity B you can read the string like so:

if(getIntent().getExtras().containsKey("stringKey"){
   String passedStr = getIntent().getStringExtra("stringKey");
}

And the original "stringValue" will be assigned to 'passedStr'.