HarmonyOS 鸿蒙Next foreach lazyforeach，列表该用哪种

@Entry
@Component
struct ListItemGroupExample {
  private list: MyDataSource2 = new MyDataSource2()
  @Builder
  itemHead(text: string) {
    Text(text)
      .fontSize(20)
      .backgroundColor(0xAABBCC)
      .width("100%")
      .padding(10)
  }
  @Builder
  itemFoot(num: number) {
    Text('共' + num + "节课")
      .fontSize(16)
      .backgroundColor(0xAABBCC)
      .width("100%")
      .padding(5)
  }
  aboutToAppear() {
    for (let date = 1; date < ~~(Math.random() * 30) + 3; date++) {
      let dayData = new dateListItem(date + "")
      for (let index = 1; index < ~~(Math.random() * 100) + 30; index++) {
        dayData.orderList.pushData(`hello${index}`)
      }
      this.list.pushData(dayData)
    }
  }
  build() {
    Column() {
      List({ space: 20 }) {
        LazyForEach(this.list, (item: dateListItem, index) => {
          ListItemGroup({ header: this.itemHead(item.date + ""), footer: this.itemFoot(item.orderList.totalCount()) }) {
            LazyForEach(item.orderList, (order: string, index2) => {
              ListItem() {
                Text(order)
                  .onAppear(() => {
                    console.info("appear:" + order, index2 + "")
                  })
                  .width("100%")
                  .height(60)
                  .fontSize(20)
                  .textAlign(TextAlign.Center)
                  .backgroundColor(0xFFFFFF)
              }
            }, (item: string) => item)
          }
          .onAppear(() => {
            console.info("appear:" + item, index + "")
          })
          .divider({ strokeWidth: 1, color: Color.Blue }) // 每行之间的分界线
        })
      }
      .cachedCount(1)
      .width('90%')
      .sticky(StickyStyle.Header | StickyStyle.Footer)
      .scrollBar(BarState.Off)
    }.width('100%').height('100%').backgroundColor(0xDCDCDC).padding({ top: 5 })
  }
}
// Basic implementation of IDataSource to handle data listener
class BasicDataSource implements IDataSource {
  private listeners: DataChangeListener[] = [];
  private originDataArray: string[] = [];
  public totalCount(): number {
    return 0;
  }
  public getData(index: number): string | dateListItem {
    return this.originDataArray[index];
  }
  // 该方法为框架侧调用，为LazyForEach组件向其数据源处添加listener监听
  registerDataChangeListener(listener: DataChangeListener): void {
    if (this.listeners.indexOf(listener) < 0) {
      console.info('add listener');
      this.listeners.push(listener);
    }
  }
  // 该方法为框架侧调用，为对应的LazyForEach组件在数据源处去除listener监听
  unregisterDataChangeListener(listener: DataChangeListener): void {
    const pos = this.listeners.indexOf(listener);
    if (pos >= 0) {
      console.info('remove listener');
      this.listeners.splice(pos, 1);
    }
  }
  // 通知LazyForEach组件需要重载所有子组件
  notifyDataReload(): void {
    this.listeners.forEach(listener => {
      listener.onDataReloaded();
    })
  }
  // 通知LazyForEach组件需要在index对应索引处添加子组件
  notifyDataAdd(index: number): void {
    this.listeners.forEach(listener => {
      listener.onDataAdd(index);
    })
  }
  // 通知LazyForEach组件在index对应索引处数据有变化，需要重建该子组件
  notifyDataChange(index: number): void {
    this.listeners.forEach(listener => {
      listener.onDataChange(index);
    })
  }
  // 通知LazyForEach组件需要在index对应索引处删除该子组件
  notifyDataDelete(index: number): void {
    this.listeners.forEach(listener => {
      listener.onDataDelete(index);
    })
  }
}
// 内层数据
class MyDataSource1 extends BasicDataSource {
  private dataArray: string[] = [];
  public totalCount(): number {
    return this.dataArray.length;
  }
  public getData(index: number): string {
    return this.dataArray[index];
  }
  public addData(index: number, data: string): void {
    this.dataArray.splice(index, 0, data);
    this.notifyDataAdd(index);
  }
  public pushData(data: string): void {
    this.dataArray.push(data);
    this.notifyDataAdd(this.dataArray.length - 1);
  }
}
// 外层数据
class MyDataSource2 extends BasicDataSource {
  private dataArray: dateListItem[] = [];
  public totalCount(): number {
    return this.dataArray.length;
  }
  public getData(index: number): dateListItem {
    return this.dataArray[index];
  }
  public addData(index: number, data: dateListItem): void {
    this.dataArray.splice(index, 0, data);
    this.notifyDataAdd(index);
  }
  public pushData(data: dateListItem): void {
    this.dataArray.push(data);
    this.notifyDataAdd(this.dataArray.length - 1);
  }
}
class dateListItem {
  date: string
  orderList: MyDataSource1
  constructor(date: string) {
    this.date = date
    this.orderList = new MyDataSource1()
  }
}