मैं एक सूची दृश्य बनाने की कोशिश कर रहा हूं, लेकिन जब मैं list_form.dart वर्ग को आयात करता हूं तो मुझे यह त्रुटि मिलती है। हो सकता है कि मैंने लेआउट में कुछ गलतियाँ की हों क्योंकि अगर मैं इसे मुख्य फ़ाइल के अंदर चलाने की कोशिश करता हूँ तो मुझे यह त्रुटि नहीं मिलती है।
यह त्रुटि है:
I/flutter (12956): ══╡ EXCEPTION CAUGHT BY RENDERING LIBRARY ╞═════════════════════════════════════════════════════════
I/flutter (12956): The following assertion was thrown during performResize():
I/flutter (12956): Vertical viewport was given unbounded height.
I/flutter (12956): Viewports expand in the scrolling direction to fill their container.In this case, a vertical
I/flutter (12956): viewport was given an unlimited amount of vertical space in which to expand. This situation
I/flutter (12956): typically happens when a scrollable widget is nested inside another scrollable widget.
I/flutter (12956): If this widget is always nested in a scrollable widget there is no need to use a viewport because
I/flutter (12956): there will always be enough vertical space for the children. In this case, consider using a Column
I/flutter (12956): instead. Otherwise, consider using the "shrinkWrap" property (or a ShrinkWrappingViewport) to size
I/flutter (12956): the height of the viewport to the sum of the heights of its children.
I/flutter (12956):
I/flutter (12956): When the exception was thrown, this was the stack:
I/flutter (12956): #0 RenderViewport.performResize.<anonymous closure> (package:flutter/src/rendering/viewport.dart:1133:15)
I/flutter (12956): #1 RenderViewport.performResize (package:flutter/src/rendering/viewport.dart:1186:6)
I/flutter (12956): #2 RenderObject.layout (package:flutter/src/rendering/object.dart:1616:9)
I/flutter (12956): #3 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #4 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #5 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #6 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #7 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #8 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #9 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #10 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #11 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #12 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #13 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #14 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #15 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #16 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #17 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #18 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #19 RenderFlex.performLayout (package:flutter/src/rendering/flex.dart:738:15)
I/flutter (12956): #20 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #21 RenderFlex.performLayout (package:flutter/src/rendering/flex.dart:738:15)
I/flutter (12956): #22 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #23 RenderPositionedBox.performLayout (package:flutter/src/rendering/shifted_box.dart:381:13)
I/flutter (12956): #24 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #25 MultiChildLayoutDelegate.layoutChild (package:flutter/src/rendering/custom_layout.dart:141:11)
I/flutter (12956): #26 _ScaffoldLayout.performLayout (package:flutter/src/material/scaffold.dart:339:7)
I/flutter (12956): #27 MultiChildLayoutDelegate._callPerformLayout (package:flutter/src/rendering/custom_layout.dart:211:7)
I/flutter (12956): #28 RenderCustomMultiChildLayoutBox.performLayout (package:flutter/src/rendering/custom_layout.dart:355:14)
I/flutter (12956): #29 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #30 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #31 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #32 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #33 _RenderCustomClip.performLayout (package:flutter/src/rendering/proxy_box.dart:1192:11)
I/flutter (12956): #34 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #35 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #36 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #37 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #38 _RenderCustomClip.performLayout (package:flutter/src/rendering/proxy_box.dart:1192:11)
I/flutter (12956): #39 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #40 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #41 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #42 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #43 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #44 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #45 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #46 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #47 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #48 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #49 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #50 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #51 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #52 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #53 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #54 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #55 RenderOffstage.performLayout (package:flutter/src/rendering/proxy_box.dart:2884:13)
I/flutter (12956): #56 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #57 RenderStack.performLayout (package:flutter/src/rendering/stack.dart:520:15)
I/flutter (12956): #58 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #59 __RenderTheatre&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #60 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #61 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #62 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #63 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #64 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #65 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #66 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #67 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #68 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #69 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #70 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #71 RenderView.performLayout (package:flutter/src/rendering/view.dart:147:13)
I/flutter (12956): #72 RenderObject._layoutWithoutResize (package:flutter/src/rendering/object.dart:1506:7)
I/flutter (12956): #73 PipelineOwner.flushLayout (package:flutter/src/rendering/object.dart:765:18)
I/flutter (12956): #74 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding.drawFrame (package:flutter/src/rendering/binding.dart:270:19)
I/flutter (12956): #75 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding&WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:674:13)
I/flutter (12956): #76 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:208:5)
I/flutter (12956): #77 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:990:15)
I/flutter (12956): #78 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:930:9)
I/flutter (12956): #79 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding.scheduleWarmUpFrame.<anonymous closure> (package:flutter/src/scheduler/binding.dart:751:7)
I/flutter (12956): #81 _Timer._runTimers (dart:isolate/runtime/libtimer_impl.dart:382:19)
I/flutter (12956): #82 _Timer._handleMessage (dart:isolate/runtime/libtimer_impl.dart:416:5)
I/flutter (12956): #83 _RawReceivePortImpl._handleMessage (dart:isolate/runtime/libisolate_patch.dart:171:12)
I/flutter (12956): (elided one frame from package dart:async)
I/flutter (12956):
I/flutter (12956): The following RenderObject was being processed when the exception was fired:
I/flutter (12956): RenderViewport#925a8 NEEDS-LAYOUT NEEDS-PAINT
I/flutter (12956): creator: Viewport ← _ScrollableScope ← IgnorePointer-[GlobalKey#8e8f7] ← Semantics ← Listener ←
I/flutter (12956): _GestureSemantics ← RawGestureDetector-[LabeledGlobalKey<RawGestureDetectorState>#67ae5] ←
I/flutter (12956): _ScrollSemantics-[GlobalKey#17eb8] ← RepaintBoundary ← CustomPaint ← RepaintBoundary ←
I/flutter (12956): NotificationListener<ScrollNotification> ← ⋯
I/flutter (12956): parentData: <none> (can use size)
I/flutter (12956): constraints: BoxConstraints(unconstrained)
I/flutter (12956): size: MISSING
I/flutter (12956): axisDirection: down
I/flutter (12956): crossAxisDirection: right
I/flutter (12956): offset: ScrollPositionWithSingleContext#c4917(offset: 0.0, range: null..null, viewport: null,
I/flutter (12956): ScrollableState, AlwaysScrollableScrollPhysics -> ClampingScrollPhysics, IdleScrollActivity#2fecf,
I/flutter (12956): ScrollDirection.idle)
I/flutter (12956): anchor: 0.0
I/flutter (12956): This RenderObject had the following descendants (showing up to depth 5):
I/flutter (12956): RenderSliverPadding#74d62 NEEDS-LAYOUT NEEDS-PAINT
I/flutter (12956): RenderSliverList#5c56d NEEDS-LAYOUT NEEDS-PAINT
I/flutter (12956): ════════════════════════════════════════════════════════════════════════════════════════════════════
I/flutter (12956): Another exception was thrown: RenderBox was not laid out: RenderViewport#925a8 NEEDS-LAYOUT NEEDS-PAINT
I/flutter (12956): Another exception was thrown: RenderBox was not laid out: RenderViewport#925a8 NEEDS-PAINT
I/flutter (12956): Another exception was thrown: RenderBox was not laid out: RenderIgnorePointer#8bbda relayoutBoundary=up11 NEEDS-PAINT
I/flutter (12956): Another exception was thrown: RenderBox was not laid out: RenderSemanticsAnnotations#209b4 relayoutBoundary=up10 NEEDS-PAINT
I/flutter (12956): Another exception was thrown: RenderBox was not laid out: RenderPointerListener#a9641 relayoutBoundary=up9 NEEDS-PAINT
I/flutter (12956): Another exception was thrown: RenderBox was not laid out: RenderSemanticsGestureHandler#9f5b4 relayoutBoundary=up8 NEEDS-PAINT
I/flutter (12956): Another exception was thrown: RenderBox was not laid out: _RenderScrollSemantics#47944 relayoutBoundary=up7 NEEDS-PAINT
I/flutter (12956): Another exception was thrown: RenderBox was not laid out: RenderRepaintBoundary#e17a8 relayoutBoundary=up6 NEEDS-PAINT
I/flutter (12956): Another exception was thrown: RenderBox was not laid out: RenderCustomPaint#a2328 relayoutBoundary=up5 NEEDS-PAINT
I/flutter (12956): Another exception was thrown: RenderBox was not laid out: RenderRepaintBoundary#02607 relayoutBoundary=up4 NEEDS-PAINT
I/flutter (12956): Another exception was thrown: RenderBox was not laid out: RenderFlex#79164 relayoutBoundary=up3 NEEDS-PAINT
I/flutter (12956): Another exception was thrown: 'package:flutter/src/rendering/shifted_box.dart': Failed assertion: line 310 pos 12: 'child.hasSize': is not true.
I/flutter (12956): Another exception was thrown: NoSuchMethodError: The method '<=' was called on null.
यह list_form.dart वर्ग है:
import 'package:flutter/material.dart';
class ListForm extends StatefulWidget {
@override
ListFormState createState() => new ListFormState();
}
class ListFormState extends State<ListForm> {
List<String> products = ["Test1", "Test2", "Test3"];
@override
Widget build(BuildContext context) {
return new Container(
child: new Center(
child: new Column(
children: <Widget>[
new Row(
children: <Widget>[
new ListView.builder(
itemCount: products.length,
itemBuilder: (BuildContext ctxt, int index) {
return new Text(products[index]);
}
),
new IconButton(
icon: Icon(Icons.remove_circle),
onPressed: () { },
)
],
mainAxisAlignment: MainAxisAlignment.spaceBetween,
),
new TextField(
decoration: new InputDecoration(
hintText: "Prodotto"
),
onSubmitted: (String str) {
setState(() {
products.add(str);
});
},
),
]
)
)
);
}
}
यह app_base.dart वर्ग है:
import 'package:flutter/material.dart';
import '../UI/list_form.dart';
class AppBase extends StatefulWidget {
@override
State createState() => new AppBaseState();
}
class AppBaseState extends State<AppBase> {
bool _pressed = true;
@override
Widget build(BuildContext context) {
return new Material(
color: Colors.greenAccent,
child: new Scaffold(
body:
new ListForm(),
appBar: AppBar(
centerTitle: true,
title: const Text('Skeeper'),
backgroundColor: Colors.green,
),
floatingActionButton: FloatingActionButton(
tooltip: 'Test',
child: new Icon(Icons.add),
backgroundColor: Colors.green,
onPressed: () {
setState(() {
_pressed = !_pressed;
});
},
),
)
);
}
}
अगर कोई अप्रयुक्त कोड है, तो चिंता न करें, यह एक कार्य प्रगति पर है और इस त्रुटि ने मुझे वही रोक दिया जो मैं कर रहा था।
