【发布时间】：2020-12-30 10:26:22
【问题描述】：
您好，这里有 Flutter 专家吗？请帮助meee ...当用户滑动图像并检查我想要在我的代码中是否相同时，我想做的是像Facebook照片查看器一样... 我制作了我的代码，因为我来自列表页面，当我点击列表时，我可以看到全屏图像..并且我可以滑动（滚动）图像... BUTTT 当我第一次出现在这个屏幕上时，它会在屏幕上显示一些错误 3,4 秒......之后我可以看到图像请帮助我并显示我的错误
Future<PhotoDetail> pagedetail() async {
sharedPreferences = await SharedPreferences.getInstance();
Map data = {
"AccessToken": sharedPreferences.getString("AccessToken"),
"CustomerId": sharedPreferences.getInt("CustomerId"),
"ImageId": indexx == null ? widget.images[widget.currentindex].photoId : indexx
};
print(data);
final http.Response response = await http.post(
Constants.CUSTOMER_WEBSERVICE_URL + "/photo/detail",
headers: <String, String>{
'Content-Type': 'application/json; charset=UTF-8',
},
body: jsonEncode(data),
);
var jsonResponse = json.decode(response.body);
if (response.statusCode == 200) {
print("Response status : ${response.statusCode}");
print("Response status : ${response.body}");
isLike = jsonResponse["IsLike"]; //here i saving value when api is run
print("iSLiked Value:" +isLike.toString()); // value is printing here
return PhotoDetail.fromJson(json.decode(response.body));
} else {
throw Exception('Failed to load data');
}
}
Future<PhotoDetail> _photoDetail;
@override
void initState() {
_photoDetail = pagedetail();
setState(() {
pagedetail(); //here is my api run when page is load
});
super.initState();
}
void pageChange(int index){ //this method is when i scroll page
setState(() {
pagedetail(); // api is call again and again
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
extendBodyBehindAppBar: true,
body: Stack(
children: <Widget>[
Container(
child:
Center(
child: PhotoViewGallery.builder(
itemCount: widget.images.length,
builder: (BuildContext context , int index) {
return PhotoViewGalleryPageOptions(
imageProvider:
NetworkImage(widget.images[index].photoPreviewImagePath),
maxScale: PhotoViewComputedScale.covered * 1.8,
minScale: PhotoViewComputedScale.contained * 1.0,
);
},
pageController: _pageController,
enableRotation: false,
scrollDirection: Axis.horizontal,
onPageChanged: pageChange,
loadingBuilder: (BuildContext context , ImageChunkEvent event){
return Center(child: CircularProgressIndicator(),);
},
)
)
),
Positioned(
bottom: 10,
left: 30,
right: 30,
child: (_photoDetail == null) ? Text("error")
: FutureBuilder<PhotoDetail>(
future: _photoDetail,
// ignore: missing_return
builder: (context , snapshot){
int like = snapshot.data.isLike;
int Slection = snapshot.data.selectedCount;
print("like ?????:" +like.toString());
print("Selection ????? :" + Slection.toString());
if (snapshot.hasData){
return Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
InkWell(
child: InkWell(
Likes();
Fluttertoast.showToast(
msg: "Liked",
toastLength: Toast.LENGTH_SHORT,
gravity: ToastGravity.BOTTOM,
timeInSecForIosWeb: 1,
backgroundColor: Color(0xfff58634),
textColor: Colors.white,
fontSize: 16.0
);
},
child: Icon(Icons.thumb_up,size: 20,color: like == 1 ? Color(0xfff58634) : Colors.white),
),
),
InkWell(
child: Icon(Icons.comment,size: 20,color: Colors.white),
),
InkWell(
onTap: (){
_onShare();
},
child: Icon(Icons.share,size: 20,color: Colors.white,),
),
InkWell(
onTap: (){},
child: Icon(Icons.photo_album,size: 20,color: Slection == 0 ? Colors.white : Color(0xfff58634)),
),
InkWell(
onTap: (){
setState(() {
viewwholike();
});
},
child: Icon(Icons.card_giftcard,size: 20,color:
Colors.white,),
),
]
);
}
else {
Text("error");
}
},
),
),
],
),
);
}
ERROR::════════ Exception caught by widgets library
═══════════════════════════════════════════════════════
The following NoSuchMethodError was thrown building
FutureBuilder<PhotoDetail>(dirty, state:
_FutureBuilderState<PhotoDetail>#ef81b):
The getter 'isLike' was called on null.
Receiver: null
Tried calling: isLike
The relevant error-causing widget was:
FutureBuilder<PhotoDetail>
file:///C:/Users/Hello%20Devloper/AndroidStudioProjects/
September/PhotoGranth-
App/lib/CampaignSinglePhotos.dart:400:15
When the exception was thrown, this was the stack:
#0 Object.noSuchMethod (dart:core-patch/object_patch.dart:53:5)
#1 _CampaignSinglePhotosState.build.<anonymous closure>
(package:photogranth2020/CampaignSinglePhotos.dart:404:42)
#2 _FutureBuilderState.build
(package:flutter/src/widgets/async.dart:732:55)
#3 StatefulElement.build
(package:flutter/src/widgets/framework.dart:4619:28)
#4 ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4502:15)
【问题讨论】：