6

在新的 Paging3 库的帮助下，我们可以轻松地在回收视图中插入项目/分隔符，如 google android codelabs 教程https://developer.android.com/codelabs/android-paging#11所示，但如何获取在每个 n 位置插入项目的逻辑就像在 recyclerview 中的每个位置 10 一样。

示例代码

fun searchRepo(queryString: String): Flow<PagingData<UiModel>> {
val lastResult = currentSearchResult
if (queryString == currentQueryValue && lastResult != null) {
    return lastResult
}
currentQueryValue = queryString
val newResult: Flow<PagingData<UiModel>> = repository.getSearchResultStream(queryString)
        .map { pagingData -> pagingData.map { UiModel.RepoItem(it) } }
        .map {
            it.insertSeparators<UiModel.RepoItem, UiModel> { before, after ->
                if (after == null) {
                    // we're at the end of the list
                    return@insertSeparators null
                }

                if (before == null) {
                    // we're at the beginning of the list
                    return@insertSeparators UiModel.SeparatorItem("${after.roundedStarCount}0.000+ stars")
                }
                // check between 2 items
                if (before.roundedStarCount > after.roundedStarCount) {
                    if (after.roundedStarCount >= 1) {
                        UiModel.SeparatorItem("${after.roundedStarCount}0.000+ stars")
                    } else {
                        UiModel.SeparatorItem("< 10.000+ stars")
                    }
                } else {
                    // no separator
                    null
                }
            }
        }
        .cachedIn(viewModelScope)
currentSearchResult = newResult
return newResult

如何在上面的示例代码中找到每10个位置添加一个项目的逻辑

fun itemInsert(position: Int): Int {
    return if (position % 10 == 0) //each 10 position is separator 
        SEPARATOR else COMMON
}
4

1 回答 1

1

我们刚刚遇到了同样的问题，我们决定手动计算索引。我们添加了：val index: Int在 RepoItem 构造函数中，其余的是：

val newResult: Flow<PagingData<UiModel>> = repository.getSearchResultStream(queryString)
    .map { pagingData ->
        var index = 0
        pagingData.map { UiModel.RepoItem(it, index++) }
    }
    .map {
        it.insertSeparators<UiModel.RepoItem, UiModel> { before, after ->
            if (before.index % 10) {
                Do something
            }
        }
    }

虽然如果您只附加数据，这可能会起作用，但如果您设置MAX_CACHE_SIZE.

于 2021-10-29T10:03:56.527 回答