Phenomenon When Admob is added in the app and the app is started, the following error occurs. java.lang.RuntimeException: Unable to get...

Overview When I have a Uri and want to convert it to a Url, I'm a little confused, so I'll share. Method String url = uri.toString();...

Problem Previously, I wrote an article that it is necessary to encode to open a URL containing Japanese. However, re-encoding an already...

Overview In dart, you can add the factory keyword to the constructor. I made the following mistake. A factory constructor is for creating...

Oveview There is a generic StatefulWidget like below. class childWidget extends StatefulWidget{ State<StatefulWidget> createState() {...

Phenomenon There is a class like below. class SomeClass{ late final String? hoge; SomeClass({this.hoge}){ hoge??= "";　//1 } } If hoge...

Overview When creating an instance of a certain class, there are cases where it is optional to set arguments to the instance, and if not...

Overview Suppose adding a class variable in dart like below. Private (don't want to be accessed from outside) Determine the value by...

Phenomenon Create a notification using flutter_local_notification. The method when tapping the notification is also registered. If the...

Overview In many cases, you'll send a message with Firebase Messaging and take some action when the notification is tapped (eg to go to a...

Overview A title error has occurred at FirebaseMessaging.onBackgroundMessage(). Cause and Solution The delegate passed to the argument of...

Overview If you are using firebase in your smartphone app, you may use different firebase projects for development and production. If you...

Phenomenon At one point, I couldn't open another app from one app. More specifically, in my app I could open a website in the browser app...

Overview If you're using firebase, you want to separate your development environment from your production environment. In this process in...

Phenomenon I get a title error when trying to import firestore with raspberry pi. from from firebase_admin import firestore ImportError:...

Phenomenon In C #, the following code causes a title compilation error. This error occurs when, for example, the class is private but the...

Overview If you want to do fitting, you can do it with scipy.optimize.leastsq etc. in python. However, when doing fitting, there are many...