Question

我希望有个美好的一天。我努力将ListView.builder包装在列中。每次尝试修复它时，都会出现此异常：

 The following RenderObject was being processed when the exception was fired:
flutter:   RenderViewport#c3792 NEEDS-LAYOUT NEEDS-PAINT
flutter:   creator: Viewport ← IgnorePointer-[GlobalKey#b696d] ← Semantics ← Listener ← _GestureSemantics ←
flutter:   RawGestureDetector-[LabeledGlobalKey<RawGestureDetectorState>#65964] ← Listener ← _ScrollableScope
flutter:   ← _ScrollSemantics-[GlobalKey#f3a27] ← Scrollable ← PrimaryScrollController ← ListView ← ⋯
flutter:   parentData: <none> (can use size)
flutter:   constraints: BoxConstraints(w=327.0, 0.0<=h<=Infinity)
flutter:   size: MISSING
flutter:   axisDirection: down
flutter:   crossAxisDirection: right
flutter:   offset: ScrollPositionWithSingleContext#60171(offset: 0.0, range: null..null, viewport: null,
flutter:   ScrollableState, AlwaysScrollableScrollPhysics -> BouncingScrollPhysics, IdleScrollActivity#63b9f,
flutter:   ScrollDirection.idle)
flutter:   anchor: 0.0
flutter: This RenderObject had the following descendants (showing up to depth 5):
flutter:   RenderSliverPadding#e4dfb NEEDS-LAYOUT NEEDS-PAINT
flutter:     RenderSliverList#17862 NEEDS-LAYOUT NEEDS-PAINT
flutter: ════════════════════════════════════════════════════════════════════════════════════════════════════
flutter: Another exception was thrown: RenderBox was not laid out: RenderViewport#c3792 NEEDS-LAYOUT NEEDS-PAINT
flutter: Another exception was thrown: RenderBox was not laid out: RenderViewport#c3792 NEEDS-PAINT
flutter: Another exception was thrown: RenderBox was not laid out: RenderIgnorePointer#8fccb relayoutBoundary=up9 NEEDS-PAINT
flutter: Another exception was thrown: RenderBox was not laid out: RenderFlex#cbeea relayoutBoundary=up2 NEEDS-PAINT
flutter: Another exception was thrown: RenderBox was not laid out: RenderPadding#0b306 relayoutBoundary=up1 NEEDS-PAINT
flutter: Another exception was thrown: NoSuchMethodError: The method '<=' was called on null.
flutter: Another exception was thrown: NoSuchMethodError: The getter 'visible' was called on null.
flutter: Another exception was thrown: NoSuchMethodError: The method '<=' was called on null.
flutter: Another exception was thrown: NoSuchMethodError: The method '<=' was called on null.
flutter: Another exception was thrown: NoSuchMethodError: The method '<=' was called on null.
flutter: Another exception was thrown: NoSuchMethodError: The method '<=' was called on null.

这是我的代码：

Padding(
          padding: EdgeInsets.all(16.0),
          child: Column(
              crossAxisAlignment: CrossAxisAlignment.stretch,
              children: <Widget>[
            Padding(
              padding: const EdgeInsets.all(8.0),
              child: ListView.builder(
                  itemCount: _messages.length,
                  itemBuilder: (context, position) {

                print(_messages.length);
                return Center(child: Text(_messages[position]));
              }),
            )
          ]))

如果有人可以帮助我，我将非常感激。

Answer 1

正如我在评论中提到的，将第二个Padding包装在Expanded小部件中即可完成工作。

包装一个listviewBuilder列内？

1 个答案: