ch06: The showData() method in build() causes repeated calls

[jialechan]

When I added print(shoppingList.length); this sentence to showData(), such as the following code:

The showData() method in build()：

Flutter-Projects/ch_06/lib/main.dart

Lines 39 to 41 in 9b16f73

	Widget build(BuildContext context) {
	showData();
	return Scaffold(

showData() source code：

Flutter-Projects/ch_06/lib/main.dart

Lines 97 to 103 in 9b16f73

	Future showData() async {
	await helper.openDb();
	shoppingList = await helper.getLists();
	setState(() {
	shoppingList = shoppingList;
	});
	}

Add print(shoppingList.length); to showData()

Future showData() async { 
   await helper.openDb(); 
   shoppingList = await helper.getLists(); 
   // print here
   print(shoppingList.length);
   setState(() { 
     shoppingList = shoppingList; 
   }); 
 }

I found that showData() is actually being called repeatedly all the time.

It seems that showData is called in build, and setState in showData will cause build to be called again, which leads to a circular call.

This should be incorrect, right? Wouldn't this lead to a waste of resources due to non-stop rebuilding?