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edittext.setOnFocusChangeListener(new View.OnFocusChangeListener() {
            @Override
            public void onFocusChange(View v, boolean hasFocus) {
                if (!hasFocus) {
                    Log.d("focus", "focus loosed");
                    // Do whatever you want here
                } else {
                    Log.d("focus", "focused");
                }
            }

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TextureView

You need to initialize TextureView before opening a camera. TextureView is for displaying the image from camera on the device. However, you cannot use it unless the texture is ready, either because the screen is currently off or it is initializing.

You should check mTextureView.isAvailable() before opening your camera. Else you will mTextureView.setSurfaceTextureListener(). And open your camera in the callback method onSurfaceTextureListener.

Camera

Before opening your camera you should check for a camera permission first.

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// # Requirement
// * `npm i form-data`


// # Test on node 14
--
import axios from 'axios'
import * as fs from 'fs'
import * as FormData from 'form-data'

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Page 1

I/O

When using Input or Output with java programming. We have serveral ways of implementing them. At the smallest and lowest level possible is FileInputStream and FileOutputStream. As the names describe one is for input the other is for output.

• Input - read files/read log
• Output - write files/print to log

FileInputStream and FileOutputStream.

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Step-by-step

https://learncssgrid.com/

Cheatsheet

http://grid.malven.co/

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function replacer(key, value) {
    if (typeof value === 'string') {
      //to avoid ///"
      //add space to , and :
      return value.replace(/"/g, '').replace(/,/g, ', ').replace(/:/g, ': ')
    } else {
      return value
    }
  }
  const jsonData = JSON.stringify(data, replacer)

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Typescript Linting

• You need to define type to each object if it does not exist then you need to create an interface.
• It is what I do every now and then when developing Android app. Yet, developing in Javascript made my lazy.

Babel configurations

• A new library may need to add a babel plugin to the .babelrc first.
• You cannot just add a new line. Don't forget to add a dependency, too.

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Docker

Docker's Concepts

• image - a snapshot of environment that just work. E.g., node10:alpine This is a super small linux (alpine) os with node10 installed.
• container - a running instance of an image. You can build container into an image and distribute the image.
• port
  • -p 4000:80 (when using command line.)

• "4000:80"

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sudo chown -R username:group node_modules

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create VPC

Instance Installation

Install NodeJS

• curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.32.0/install.sh | bash
• . ~/.nvm/nvm.sh
• nvm install 10.14.2
• node -e "console.log('Running Node.js ' + process.version)"