I have an unsolved problem: what I want to do: I have an activity with a TextView which shows the mathematical sum of all items: example. The Listview contains several items which have an amount (double). I want to show the sum of all items inside the activity.

Generally, it works fine when the activity runs the first time, but if I add an item to the list (with a button) later on it is shown correctly inside the list. but I have to update the Textview in the activity. how can I do that, because I don't know a function which tells me that da dataset has changed?

what works actually:

• the activity, the sum calculation, and the Listview (with custom adapter).
• In the Listview there is a checkbox, when it is changed a dialog is opened where the new amount is inserted. (that is all done in the adapter)
• everything is correctly shown in the listview after a change

What should be solved:

• Now, as soon as the dialog box is closed, the sum in the activity (which is outside of the Listview) has to be updated. but how do I get that information back to my activity?

Thank you for your support!

Best regards Jason

CodePudding user response：

The ListView is in the mainactivity and works fine. In the custom Adapter I can change some date of the Item (each line). Now the Data and ListView is updated and correctly shown. But not The TextView in the mainactivity.

I solved it now by passing the TextView object to the Custom Adapter and do the setText(....) there