How to obtain/get copied image from clipboard data in browser

JS code works well for Chrome, Firefox and Safari

    const source = document.querySelector('.source');
    source.addEventListener('paste', (event) => {
        if (event.clipboardData && 
            event.clipboardData.items && 
            event.clipboardData.items.length == 1) {
                const item = event.clipboardData.items[0];
                if (item.kind == 'file' && item.type == 'image/png') {
                        let blob = item.getAsFile();
                        let f = new FileReader();
                        f.onload = (e) => {
                                console.log(e.target.result);
                        }
                        f.readAsDataURL(blob);
                }
        }
        event.preventDefault();
    });

Image source to data base64 url from clipboard data

How to add Lombok to your project : Lombok Dependency is missing

Lombok Dependency is missing

How to add Lombok to your project

Amazon Interview Tips: 亚马逊面试经验

Amazon tag on lintcode problems

https://www.lintcode.com/problem/?tag=amazon

Amazon behavioral interview questions

https://interviewgenie.com/blog-1/interviewing-at-amazon-behavioral-interview-questions

Amazon Leadership Principles

https://www.amazon.jobs/en/principles

Java learning: possible lossy conversion from int to short

fault code

 short s = 5; s = s - 2; 

 error: incompatible types: possible lossy conversion from int to short         s = s - 2;               ^ 1 error 

Correct code

 // why below line ok ? ask java compiler. s -= 2; s = (short)(s - 2); 

Java report error while c/c++ do not even display a warning message

in fact, c++ do the same things like Java do:
Automatic promotion of shot to int, but implicit the conversion.

Java learning: why float a = 5.6; compile error ?

why can't float a = 5.6; ?

 error: incompatible types: possible lossy conversion from double to float         float a = 5.6;                   ^ 1 error 

Cause

double is the default type of floating point number in java language.

Fix

 float a = 5.6f; 

Java learning: Hello World program with java

Recently, I begin to use java in my work. I used to c++ for more than 10 years.

Programmer start every thing begin with Hello World

public class HelloWorld {                                                       
    public static void main(String[] args) {
        System.out.println("Hello World!");
    }
}

Java main function, must be in a public class

 public static void main(String[] args) {} 

Compile HelloWorld

javac HelloWorld.java

Execute HelloWorld

java HelloWorld
remember, not java HelloWorld.class
otherwise, you will got below error
Error: Could not find or load main class HelloWorld.class