android - Back button and refreshing previous activity

Question

If we have two activities:

1. List of files and last modified time
2. File editing activity

A user selects a file from the list and is taken to the file editing activity. When done editing, the user presses the back button to return to the file list.

The list is not reloaded and therefore an incorrect value is displayed for the just edited files modified time.

What is the proper method of causing the file list to refresh after the back button is pressed?

This example assumes that no database is being used, just an ArrayAdapter.

Answer 1

One option would be to use the onResume of your first activity.

@Override
public void onResume()
    {  // After a pause OR at startup
    super.onResume();
    //Refresh your stuff here
     }

Or you can start Activity for Result:

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

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 write following code for onActivityResult() method

protected void onActivityResult(int requestCode, int resultCode, Intent data) {

  if (requestCode == 1) {

     if(resultCode == RESULT_OK){      
         //Update List         
     }
     if (resultCode == RESULT_CANCELED) {    
         //Do nothing?
     }
  }
}//onActivityResult