Passing values to activities using Extras: Android Programming

Demonstrate passing a value to an activity when it is created, and passing a value back (returning) when it finishes. Complete source code available at https://github.com/drbfraser/video-tutorial-code/tree/master/ExtrasDemo Passing To an Activity: ----------------------- Pass data to an activity from MainActivity: Intent intent = new Intent(MainActivity.this, DisplayActivity.class); intent.putExtra("my parameter name", 42); startActivity(intent); Getting value in second activity's onCreate(): Intent intent = getIntent(); int myValue = intent.getIntExtra("my parameter name", 0); // 0 is the default value if the parameter not set. Returning a value: ------------------ Change calling code (1st activity) to use startActivityForResult(): Intent intent = new Intent(MainActivity.this, DisplayActivity.class); intent.putExtra("my parameter name", 42); startActivityForResult(intent, 12345); // 12345 is a code to myself to identify which call is returning. Set data in the called activity (2nd activity): Intent returnData = new Intent(); returnData.putExtra("my answer", 24); setResult(Activity.RESULT_OK, returnData); // use Activity.RESULT_CANCELED to indicate failure. finish(); Catch the return value in 1st activity's onActivityResult: protected void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data); switch(requestCode) { case 12345: if (resultCode == Activity.RESULT_OK) { int answer = data.getIntExtra("my answer", 0); // 0 is default value if none was specified // Do something with the answer... break; } }