Jetpack 撰写如何跳过 LazyVerticalGrid / java.lang.IllegalStateException 中的一项：检查失败答案

【问题标题】：Jetpack compose how to skip one item in a LazyVerticalGrid / java.lang.IllegalStateException: Check failedJetpack 撰写如何跳过 LazyVerticalGrid / java.lang.IllegalStateException 中的一项：检查失败
【发布时间】：2023-01-27 00:48:12
【问题描述】：

我开始使用 Jetpack Compose。我正在创建一个网格来显示一些带有一些文本的框。问题是我从我的 api 获取我的数据，有些可能为空。所以我想在我的网格中跳过这个项目，但它不起作用。这是我的代码：

val spanCount = 2
LazyVerticalGrid(
    cells = GridCells.Fixed(spanCount),
    state = rememberLazyListState(),
) {
            items(datafromapi) { result ->
            Box(modifier = Modifier
                                    .clickable {
                                       //todo
                                    }
                                    .padding(8.dp)) {
                                    Text(result.title)
                                }
        }

我从 api 获得的结果是一个具有多个字符串的对象，标题是其中之一，而不是我需要在这里使用的。问题是有时标题为空然后当它发生时我得到这个错误：

E/AndroidRuntime:     at androidx.compose.runtime.ComposerImpl$CompositionContextImpl.composeInitial$runtime_release(Composer.kt:2987)
    at androidx.compose.runtime.CompositionImpl.setContent(Composition.kt:433)
    at androidx.compose.ui.layout.SubcomposeLayoutState.subcomposeInto(SubcomposeLayout.kt:269)
    at androidx.compose.ui.layout.SubcomposeLayoutState.access$subcomposeInto(SubcomposeLayout.kt:154)
    at androidx.compose.ui.layout.SubcomposeLayoutState$subcompose$2.invoke(SubcomposeLayout.kt:244)
    at androidx.compose.ui.layout.SubcomposeLayoutState$subcompose$2.invoke(SubcomposeLayout.kt:241)
    at androidx.compose.runtime.snapshots.SnapshotStateObserver.withNoObservations(SnapshotStateObserver.kt:142)
    at androidx.compose.ui.node.OwnerSnapshotObserver.withNoSnapshotReadObservation$ui_release(OwnerSnapshotObserver.kt:55)
    at androidx.compose.ui.node.LayoutNode.withNoSnapshotReadObservation$ui_release(LayoutNode.kt:1175)
    at androidx.compose.ui.layout.SubcomposeLayoutState.subcompose(SubcomposeLayout.kt:241)
    at androidx.compose.ui.layout.SubcomposeLayoutState.subcompose(SubcomposeLayout.kt:235)
    at androidx.compose.ui.layout.SubcomposeLayoutState.subcompose$ui_release(SubcomposeLayout.kt:224)
    at androidx.compose.ui.layout.SubcomposeLayoutState$Scope.subcompose(SubcomposeLayout.kt:490)
    at androidx.compose.foundation.lazy.layout.LazyLayoutPlaceablesProvider.getAndMeasure-0kLqBqw(LazyMeasurePolicy.kt:58)
    at androidx.compose.foundation.lazy.list.LazyMeasuredItemProvider.getAndMeasure-oA9-DU0(LazyMeasuredItemProvider.kt:45)
    at androidx.compose.foundation.lazy.list.LazyListMeasureKt.measureLazyList-wroFCeY(LazyListMeasure.kt:145)
    at androidx.compose.foundation.lazy.list.LazyListKt$rememberLazyListMeasurePolicy$1$1.measure-3p2s80s(LazyList.kt:259)
    at androidx.compose.foundation.lazy.layout.LazyLayoutKt$LazyLayout$2.invoke-0kLqBqw(LazyLayout.kt:55)
    at androidx.compose.foundation.lazy.layout.LazyLayoutKt$LazyLayout$2.invoke(LazyLayout.kt:44)
    at androidx.compose.ui.layout.SubcomposeLayoutState$createMeasurePolicy$1.measure-3p2s80s(SubcomposeLayout.kt:355)
    at androidx.compose.ui.node.InnerPlaceable.measure-BRTryo0(InnerPlaceable.kt:55)
    at androidx.compose.ui.node.DelegatingLayoutNodeWrapper.measure-BRTryo0(DelegatingLayoutNodeWrapper.kt:131)
    at androidx.compose.ui.node.DelegatingLayoutNodeWrapper.measure-BRTryo0(DelegatingLayoutNodeWrapper.kt:131)
    at androidx.compose.ui.node.DelegatingLayoutNodeWrapper.measure-BRTryo0(DelegatingLayoutNodeWrapper.kt:131)
    at androidx.compose.ui.node.DelegatingLayoutNodeWrapper.measure-BRTryo0(DelegatingLayoutNodeWrapper.kt:131)
    at androidx.compose.ui.node.DelegatingLayoutNodeWrapper.measure-BRTryo0(DelegatingLayoutNodeWrapper.kt:131)
    at androidx.compose.ui.node.DelegatingLayoutNodeWrapper.measure-BRTryo0(DelegatingLayoutNodeWrapper.kt:131)
    at androidx.compose.ui.graphics.SimpleGraphicsLayerModifier.measure-3p2s80s(GraphicsLayerModifier.kt:306)
    at androidx.compose.ui.node.ModifiedLayoutNode.measure-BRTryo0(ModifiedLayoutNode.kt:39)
    at androidx.compose.ui.node.DelegatingLayoutNodeWrapper.measure-BRTryo0(DelegatingLayoutNodeWrapper.kt:131)
    at androidx.compose.ui.node.OuterMeasurablePlaceable$remeasure$2.invoke(OuterMeasurablePlaceable.kt:99)
    at androidx.compose.ui.node.OuterMeasurablePlaceable$remeasure$2.invoke(OuterMeasurablePlaceable.kt:98)
    at androidx.compose.runtime.snapshots.SnapshotStateObserver.observeReads(SnapshotStateObserver.kt:126)
    at androidx.compose.ui.node.OwnerSnapshotObserver.observeReads$ui_release(OwnerSnapshotObserver.kt:88)
    at androidx.compose.ui.node.OwnerSnapshotObserver.observeMeasureSnapshotReads$ui_release(OwnerSnapshotObserver.kt:76)
    at androidx.compose.ui.node.OuterMeasurablePlaceable.remeasure-BRTryo0(OuterMeasurablePlaceable.kt:98)
    at androidx.compose.ui.node.OuterMeasurablePlaceable.measure-BRTryo0(OuterMeasurablePlaceable.kt:75)
    at androidx.compose.ui.node.LayoutNode.measure-BRTryo0(LayoutNode.kt:1308)

所以我认为这是因为我的标题是空的，我想对此添加一个检查，但它似乎不起作用我试图在框启动之前添加一个检查：

val spanCount = 2
LazyVerticalGrid(
    cells = GridCells.Fixed(spanCount),
    state = rememberLazyListState(),
) {
            items(datafromapi) { result ->
            if (!result.tile.isNullOrEmpty){
               Box(modifier = Modifier
                                    .clickable {
                                       //todo
                                    }
                                    .padding(8.dp)) {
                                    Text(result.title)
                                }
                    }
        }

但这并没有解决我的问题，我还遇到了另一个错误：

 java.lang.IllegalStateException: Check failed.
    at androidx.compose.foundation.lazy.LazyGridKt$ItemRow$2.measure-3p2s80s(LazyGrid.kt:451)
    at androidx.compose.ui.node.InnerPlaceable.measure-BRTryo0(InnerPlaceable.kt:55)
    at androidx.compose.ui.node.OuterMeasurablePlaceable$remeasure$2.invoke(OuterMeasurablePlaceable.kt:99)
    at androidx.compose.ui.node.OuterMeasurablePlaceable$remeasure$2.invoke(OuterMeasurablePlaceable.kt:98)
    at androidx.compose.runtime.snapshots.SnapshotStateObserver.observeReads(SnapshotStateObserver.kt:126)
    at androidx.compose.ui.node.OwnerSnapshotObserver.observeReads$ui_release(OwnerSnapshotObserver.kt:88)
    at androidx.compose.ui.node.OwnerSnapshotObserver.observeMeasureSnapshotReads$ui_release(OwnerSnapshotObserver.kt:76)
    at androidx.compose.ui.node.OuterMeasurablePlaceable.remeasure-BRTryo0(OuterMeasurablePlaceable.kt:98)
    at androidx.compose.ui.node.OuterMeasurablePlaceable.measure-BRTryo0(OuterMeasurablePlaceable.kt:75)
    at androidx.compose.ui.node.LayoutNode.measure-BRTryo0(LayoutNode.kt:1308)
    at androidx.compose.foundation.lazy.layout.LazyLayoutPlaceablesProvider.getAndMeasure-0kLqBqw(LazyMeasurePolicy.kt:61)
    at androidx.compose.foundation.lazy.list.LazyMeasuredItemProvider.getAndMeasure-oA9-DU0(LazyMeasuredItemProvider.kt:45)
    at androidx.compose.foundation.lazy.list.LazyListMeasureKt.measureLazyList-wroFCeY(LazyListMeasure.kt:145)
    at androidx.compose.foundation.lazy.list.LazyListKt$rememberLazyListMeasurePolicy$1$1.measure-3p2s80s(LazyList.kt:259)
    at androidx.compose.foundation.lazy.layout.LazyLayoutKt$LazyLayout$2.invoke-0kLqBqw(LazyLayout.kt:55)
    at androidx.compose.foundation.lazy.layout.LazyLayoutKt$LazyLayout$2.invoke(LazyLayout.kt:44)
    at androidx.compose.ui.layout.SubcomposeLayoutState$createMeasurePolicy$1.measure-3p2s80s(SubcomposeLayout.kt:355)
    at androidx.compose.ui.node.InnerPlaceable.measure-BRTryo0(InnerPlaceable.kt:55)
    at androidx.compose.ui.node.DelegatingLayoutNodeWrapper.measure-BRTryo0(DelegatingLayoutNodeWrapper.kt:131)
    at androidx.compose.ui.node.DelegatingLayoutNodeWrapper.measure-BRTryo0(DelegatingLayoutNodeWrapper.kt:131)
    at androidx.compose.ui.node.DelegatingLayoutNodeWrapper.measure-BRTryo0(DelegatingLayoutNodeWrapper.kt:131)
    at androidx.compose.ui.node.DelegatingLayoutNodeWrapper.measure-BRTryo0(DelegatingLayoutNodeWrapper.kt:131)
    at androidx.compose.ui.node.DelegatingLayoutNodeWrapper.measure-BRTryo0(DelegatingLayoutNodeWrapper.kt:131)
    at androidx.compose.ui.node.DelegatingLayoutNodeWrapper.measure-BRTryo0(DelegatingLayoutNodeWrapper.kt:131)
    at androidx.compose.ui.graphics.SimpleGraphicsLayerModifier.measure-3p2s80s(GraphicsLayerModifier.kt:306)
    at androidx.compose.ui.node.ModifiedLayoutNode.measure-BRTryo0(ModifiedLayoutNode.kt:39)
    at androidx.compose.ui.node.DelegatingLayoutNodeWrapper.measure-BRTryo0(DelegatingLayoutNodeWrapper.kt:131)
    at androidx.compose.ui.node.OuterMeasurablePlaceable$remeasure$2.invoke(OuterMeasurablePlaceable.kt:99)
    at androidx.compose.ui.node.OuterMeasurablePlaceable$remeasure$2.invoke(OuterMeasurablePlaceable.kt:98)
    at androidx.compose.runtime.snapshots.SnapshotStateObserver.observeReads(SnapshotStateObserver.kt:126)
    at androidx.compose.ui.node.OwnerSnapshotObserver.observeReads$ui_release(OwnerSnapshotObserver.kt:88)
    at androidx.compose.ui.node.OwnerSnapshotObserver.observeMeasureSnapshotReads$ui_release(OwnerSnapshotObserver.kt:76)
    at androidx.compose.ui.node.OuterMeasurablePlaceable.remeasure-BRTryo0(OuterMeasurablePlaceable.kt:98)
    at androidx.compose.ui.node.OuterMeasurablePlaceable.measure-BRTryo0(OuterMeasurablePlaceable.kt:75)
    at androidx.compose.ui.node.LayoutNode.measure-BRTryo0(LayoutNode.kt:1308)
    at androidx.compose.foundation.layout.RowColumnImplKt$rowColumnMeasurePolicy$1.measure-3p2s80s(RowColumnImpl.kt:89)
    at androidx.compose.ui.node.InnerPlaceable.measure-BRTryo0(InnerPlaceable.kt:55)

所以我试着把条件放在文本之前的框中，如下所示：

if (!issue.title.isNullOrEmpty()){
    Text(issue.title)}

这没有崩溃问题是我的网格中有一个空的空白框，我想摆脱它。

所以我最后只想在我的网格项目上添加一个检查，并在特定条件下不显示该项目。感谢您的帮助。

【问题讨论】：

标签： android kotlin android-jetpack-compose lazyvgrid android-jetpack-compose-lazy-column

【解决方案1】：

我建议一些方法：

如果您有一个 State Holder（ViewModel 或普通类）来保存可组合项的状态，请在那里进行验证并在进入视图之前过滤空值。
您可以使用 remember 然后在您的列表中使用它：
```
    val dataFiltered = remember { mutableStateListOf(datafromapi.filter { it.title.isNullOrBlank().not() }) }
```
1. 过滤来自您的 API 的数据，以便任何客户端都将获得正确的值而不是空值。
我不太喜欢第二种选择，但那可能是一种选择。

验证中发生的事情被认为是副作用，因为这是影响可组合项的外部行为，因此最好的方法是在数据到达您的 UI 之前从外部处理它。

【讨论】：