Flutter

问题 Suppose I want to initialize a text field by using the initialValue: property on a TextFormField , and I need my initial value to come from a provider. I read on the docs that calling read() from inside the build method is considered bad practice, but calling from handlers is fine (like onPressed ). So I'm wondering if its fine to call read from the initialValue property like shown below? 回答1: No, you should use useProvider if you are using hooks, or a ConsumerWidget / Consumer if you are not

问题 I need some suggestions or help please. I am trying to do a small real time chat application, most tutorials that I have been looking basically use firebase, but I have been using MySQL already for other parts of my small projects, I am not sure if I understood Stream correctly, but as far as I know I think that the data does keep fetching, I tried it but it didn't update the new data, and besides StreamBuilder being a little hard to use, I went for the easiest method using a regular http and

问题 I modified description value to 1 on my database. List<DataEquipmentReg> values = snapshot.data; assetArray.add('${values[i].eq_no.toString()} : ${values[i].description.toString()}'); After edit description value to String , Error is not coming DataEquipmentReg POJO Class class DataEquipmentReg { final String eq_no; final String description; } Widget Text(assetArray[index].toString(),), Database in sqlite await db.execute("""CREATE TABLE EquipmentRegTable(eq_no STRING, description STRING)""")

问题 I have been already running flutter and android studio. Today i just updated the android studio to latest version 4.1 after upgrading when i run the flutter doctor. I am getting the following error. I have installed flutter and dart plugins in the android studio. Staring new flutter project is showing in the welcome screen But when i run the flutter doctor in the terminal its says Flutter plugin not installed. I have attached the vim bash file too I am not able to find whats the issue. Thanks

问题 When calling textfield on flutter in fireOS in the fire tv devices, to do a search for example the fireOS virtual keyboard pops on top of textfield and doesnt work like on other android devices where the keyboard is on the bottom and textfield is visible. On android legacy for example i can use edittext widget and the same keyboard pops on top but whatever i type with the controller updates on the virtual keyboard itself, because the keyboard has its own textfield or edittext. So my problem

问题 I've made a GridView , but now I have some ListTiles in this GridView that I need to be selected Upon selection, I want the background color to change. And I am also facing one more issue, I want to custom the heights of these ListTile , but I am not getting any success to do so. I am gonna attach the picture the output that I am getting and the output that I want. What I am getting: What I want: Here is the code: class _SelectLanguageNewState extends State<SelectLanguageNew> { List<Results>

问题 I'm fetching coordinates from Firestore to fill my map with stores locations. The Google Map Marker needs a LatLng object (that takes two double as parameters) with the latitude and longitude of a point. But, for each increment, I get the following exception: type 'String' is not a subtype of type 'double' (verbose down below). However, the points do appear on the map, which should mean that the values ARE of type double... I used the following code to identify the latitude and longitude type

问题 I've made a GridView , but now I have some ListTiles in this GridView that I need to be selected Upon selection, I want the background color to change. And I am also facing one more issue, I want to custom the heights of these ListTile , but I am not getting any success to do so. I am gonna attach the picture the output that I am getting and the output that I want. What I am getting: What I want: Here is the code: class _SelectLanguageNewState extends State<SelectLanguageNew> { List<Results>

问题 If I have an arbitrary String like this: final family = '\u{1F468}\u{200D}\u{1F469}\u{200D}\u{1F467}'; // 👨‍👩‍👧 final myString = 'Let me introduce my $family to you.'; And I know the String index of the character after the family emoji (the space) is 28 , how do I find the String index of the first code unit of the family emoji? In other words, how to I find the length in UTF-16 code units of the family emoji? I've asked a similar question before, but that was before the characters package

问题 If I have an arbitrary String like this: final family = '\u{1F468}\u{200D}\u{1F469}\u{200D}\u{1F467}'; // 👨‍👩‍👧 final myString = 'Let me introduce my $family to you.'; And I know the String index of the character after the family emoji (the space) is 28 , how do I find the String index of the first code unit of the family emoji? In other words, how to I find the length in UTF-16 code units of the family emoji? I've asked a similar question before, but that was before the characters package