KKのGreen Tea Cafe

[Flutter]Define a Global BuildContext & Its Usage

*This post is more like a note to myself. It’s simple, just add static keyword when defining a BuildContext. It’s useful when you want to display a Toast or SnackBar in global context, or update an UI, the data will update, not only within one context (context of current page or exited or popped page and so on) but also in other contexts. For example: //To define global context class…

Flutter: Easy Way to Disable or Enable a Button

I spent hours on implementing disabling and enabling a button (Material button, raised button, outline button and so on) below a list of Radio group with setState({}) and Shared Preference, in order to save the value of isPressed variable permanently, I even tried with FutureBuilder and Bloc… The purpose I was trying to accomplish is the button should be disabled once it’s pressed, and enabled…

Dart Flutter: Custom Radio Button – Save Selection State with MemoryKeyValueStore (or SharedPreferences)

First, create a custom radio button with a RadioButtonModel class, UI only. import 'package:flutter/cupertino.dart'; import 'package:flutter/material.dart'; import 'package:flutter_svg/svg.dart'; class RadioGroup extends StatefulWidget { final RadioButtonModel _item; RadioGroup(this._item); @override State<StatefulWidget> createState() { return _RadioGroup(); } } class _RadioGroup extends…

Flutter App Dev: Button and Start New Activity

I have just started to learn Dart for Flutter app development. If you are familiar with Java, Dart will be quite easy for you.

Here’s just a very simple sample for button on clicks and activity navigation.

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How to Generate Signed Android App Bundle

Since Google Play has warned the developers

Ref link: https://support.google.com/googleplay/android-developer/answer/9303479

Signing a Android App Bundle file becomes a must.

Following are the steps to build a such bundle.

First, you have to generate a .jks or .keystore file with Google Play signing.

You can either do this with CMD/Terminal or just use the Android Studio’s Generate…

Android: Set Value Over Seek Bar Thumb

Create a seek_bar_preference.xml, inside this xml file, use AppCompatSeekBar, and AppCompatTextView for the progress value text:

Android: Google Sign-In Implementation Tutorial

I spent about 2 days on implementing the Google sign in, and got the ID token with key SHA-1 signing certificate and google’s client-id. The key part of Google sign-in is to generate the appropriate and correct SHA-1 signing certificate and get the corresponding client-id.

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How to Generate A Java Keystore for Android Apps

This tutorial is focus on how to generate Java keystores for Android Apps.

What you need:

A Bash/Shell (Git Bash works too), CMD, or any Terminal

Java JDK installed, and Java environment set

There are 3 types of keystores you can generate for your Android application:

The keystore for signing Android apps

The release keystore

The debug keystore

The following steps will tell you how to create

Generate JKS KeyStore From Existing Keystore & Use it in Android Apps

Note: This tutorial only works when you already have a keystore.

Go to the location where your keystores are; or open CMD, use cd [path to the keystore(s)] to go to the location.

In this folder, on the CMD, or Gitbash, or other Terminals, type following command (for keytool.exe, see Facebook API: Key Hash for Android App):

"C:\Program Files (x86)\Java\jre1.8.0_251\bin\keytool" -importkeystore…

For Windows,run CMD (Command Prompt),give the path for .android folder

cd PATH_WHERE_.android_LOCATED for example: C:\Users\USER_NAME\.android

In this folder copy paste following command: It’s better to specify the path to the executable keytool (keytool.exe). Android SDK folder doesn’t have keytool.exe

Find the Java’s jre[version]\bin\keytool path in your local,it’s usually located inC:\Program…

It’s actually pretty easy when you understand the logic.

The Transition name must be the same. There are two ways to get the transition name (or maybe 3)

1. Use ViewCompat.getTransitionName([view that has the transition name],[the transition name]) 2. Call setTransitionName() on devices running Lollipop and up. 3. Add element to strings.xml in value folder, and reuse it.

If you want to make…

Yesterday, I was trying to make location permissions request, and I discovered that the onRequestPermissionResult() method can neither be overwritten in Activities (which extends AppCompatActivity) nor Fragments.

I changed the current SDK version 29, to 28, sync the project, and hard-coded the onRequestPermissionResult() with @Overrideannotation, in order to see if this was the problem (I was…

Android: Kotlin Android Extensions – View Binding

What is Kotlin Android Extensions View Binding?

View Binding is a feature that allows you to more easily write code that interacts with Views. Kotlin Android Extensions is a plugin that does not require annotating fields for each exposed View and it allow us to perform View Binding without having to add any extra code.

What does Kotlin Android Extensions View Binding do?

Applying Kotlin Android…

Android: Download Manager and Request Permission In Fragments

The traditional way of downloading an image or a file is first to get the URL, create an InputStream instance, open the URL by using the HttpURLConnection class, then decode the bitmap or file and compress them and put the input stream instance to the decoded bitmap or file. This way, we need to put all the code into the doInBackground() method of AsyncTask class (will get exception otherwise),…

Android Wave Tutorial

Python Basics: Module & Namespace

A module in Python is a Python source file that contains definitions and use them in a script or in an interactive instance of the interpreter. We use modules to divide a piece of software into separate but cooperating parts. (more…)

Android Basics: Calendar Class

Documentation for the Calendar class Use Calendar.getInstance() to get current date time; very similar in Kotlin. (more…)