从不同的活动更新ListAdapter

Question

I am working on my hobby project to learn more about android programming and stuffs. So i recently ran into a simple problem but couldn't find a solution for it.

My project for now have 2 activity [MainActivity] , [CommentActivity] .

In MainActivity, I have a listadapter (cusAdapter) will fetch all the content from a database and display it on a listview. Everything works fine there. It will fetch all the comments and total comments for a certain post based on the post id. In the same MainActivity, i have a comment button and a onclick listener which when clicked will bring user to the next activity [CommentActivity] and load all the comments and data needed using another custom adapter. I also have a total comment TextView that will show the total comment fetched by the json and display it in my listview.

When a user posted a comment on CommentActivity, it will save into the database via AsyncTask.

Now the problem is, when i press back button and navigate back from CommentActivity to MainActivity, i use intent with flag (intent.flag_activity_reorder_to_front). So it will never reload the MainActivity again when back button is pressed. Also it will never update the total comment in the MainActivity. What i want to do is when back button is pressed on CommentActivity, i want it to refresh/reload the ListAdapter in MainActivity to fetch the latest data from database.

Also i don't want to reload the whole MainActivity, i just wanna update the view without reloading the whole activity.

I believe there must be some easy way to do this. I can post codes if you guys need it to assists me.

Thank you.

Answer 1

In your MainActivity you could check in onResume to see if the data has changed, as this will be called when you go back to it from the CommentActivity.

If the data has changed, calling notifyDataSetChanged() on the adapter will reload the view with the new data

Answer 2

Yes, there is an easy way. Start your sencond activity using:

• startActivityForResult(intent, RESULT_CODE)
• use setResult(RESULT_OK) in your second activity after doing the commit of the changes to the database
• override onActivityResult() in your first activity to check when the second activity returns properly
• update the first adapter as needed.

Hope it helps.