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Java String

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What is String in Java?

Java String is a sequence of characters.

Java String variable contains a collection of characters surrounded by double quotes.

An array of characters works same as Java String.

Java Strings are used for storing text.

In Java, Strings are immutable or final or constant which means each time when we are creating or editing or performing any method to change string, one string created in "String Constant Pool"

How to create a String in Java?

There are two ways to create a String object:

  1. By string literal
  2. By new keyword

JavaScript ES6 Classes and Arrow Functions

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I try to understand difference between function expression, shorthand method definition, arrow function and bind().

Notice that I defined sayGoodBye() function in constructor, it means that whenever i create a new instance from this Person class, sayGoodBye() function will be defined for every instance.

sayHello() function is defined as a class property. But, as you can see in the following screenshot, class properties are also defined in constructor so class properties are just a sugar syntax.

getFullName() function is defined as shorthand method definition. But, Babel didn't move function definition in class constructor. So, if we use shorthand method definition in class, it will be a prototype function .

It mean they are only defined once, instead of once per instance.

Notice that in below screenshot, getFullName() function is in prototype of Person class, but sayHello() and sayGoodBye() are not.

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JavaScript Three Ways of Handling Asynchronous Operations

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There is one more post about Promise and Async/Await usage in the following link.

JavaScript Promise and Async/Await

There are 3 ways to handle asynchronous function calls.

Using Callbacks

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Node.js Mocha and Chai

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Mocha is a test framework to run tests.

https://mochajs.org/#assertions

Chai is an assertion library and you can find full documentation in the following link.

https://www.chaijs.com/api/bdd/

There are three type of assertion libraries in Chai.

  • Expect
  • Should
  • Assert

expect and should use the same chainable language to construct assertions.

Assume that expect library is used like below

expect(firstName).to.be.a('string');
expect(firstName).to.equal('kenan');
expect(firstName).to.have.lengthOf(5);
expect(beverages).to.have.property('tea').with.lengthOf(3);

Above code could be written with should library like below.

firstName.should.be.a('string');
firstName.should.equal('kenan');
firstName.should.have.lengthOf(5);
beverages.should.have.property('tea').with.lengthOf(3);

You can find more detailed usage with Express, Mocha and Chai in the following repository

https://github.com/nodejs-projects-kenanhancer/express-demo.git

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Find Interaction Algorithm

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FindIntersection(strArr) read the array of strings stored in strArrwhich will contain 2 elements: the first element will represent a list of comma-separated numbers sorted in ascending order, the second element will represent a second list of comma-separated numbers (also sorted). Your goal is to return a comma-separated string containing the numbers that occur in elements of strArr in sorted order. If there is no intersection, return the string false. 

Demo 1

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