Android developer : How to start activity for result.

Calling a second activity from the main activity by startActivityForResult. When second activity is finish, it will send back result (some data) to main activity.
How main activity get the result ?

From your FirstActivity call the SecondActivity using startActivityForResult() method

 Intent i = new Intent(this, SecondActivity.class);  
 startActivityForResult(i, 1);  

In your SecondActivity set the data which you want to return back to FirstActivity. If you don't want to return back, don't set any.

For example: In secondActivity if you want to send back data:

 Intent returnIntent = new Intent();  
 returnIntent.putExtra("result",result);  
 setResult(RESULT_OK,returnIntent);  
 finish();  

If you don't want to return data:

 Intent returnIntent = new Intent();  
 setResult(RESULT_CANCELED, returnIntent);  
 finish();  

Now in your FirstActivity class override onActivityResult() method. And process intent data by resultCode.

 protected void onActivityResult(int requestCode, int resultCode, Intent data) {  
   if (requestCode == 1) {  
     if(resultCode == RESULT_OK){  
       String result=data.getStringExtra("result");  
     }  
     if (resultCode == RESULT_CANCELED) {  
       //Write your code if there's no result  
     }  
   }  
 }

reference : http://stackoverflow.com/questions/10407159/how-to-manage-start-activity-for-result-on-android