我想这段代码可以帮助你：

class MyHomePage extends StatelessWidget {
  const MyHomePage({super.key});

  @override
  Widget build(BuildContext context) {
    List<ExampleClass> listItem = [
      ExampleClass(useDate: 231022, amount: 1000),
      ExampleClass(useDate: 231022, amount: 2000),
      ExampleClass(useDate: 230519, amount: 3000),
      ExampleClass(useDate: 230518, amount: 4000),
    ];
    return Material(
      child: ListView.builder(
        itemCount: listItem.length,
        itemBuilder: (context, index) {
          return Column(
            children: [
              if (index == 0)
                Text("${listItem[index].useDate}")
              else if (listItem[index].useDate != listItem[index - 1].useDate)
                Text("${listItem[index].useDate}"),
              Row(
                children: [
                  const Icon(Icons.add),
                  Text("${listItem[index].amount}"),
                ],
              )
            ],
          );
        },
      ),
    );
  }
}

class ExampleClass {
  final int useDate;
  final int amount;

  ExampleClass({required this.useDate, required this.amount});
}

您的类Map自JSON数据，可以替换ExampleClass。