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Object Oriented Programming Articles
Page 497 of 589
What is the difference between non-static methods and abstract methods in Java?
Following are the notable differences between non-static methods and abstract methods.Non-static (normal) methodsAbstract methodsThese methods contain a body.Abstract methods don’t have body these are ended with a semicolonYou can use normal method directly.You cannot use abstract methods directly, to use them you need to inherit them and provide body to these methods and use them.Example:public void display() { System.out.println("Hi"); }Example:public void display();
Read MoreHow to write the comparator as a lambda expression in Java?
A lambda expression is an anonymous method and doesn't execute on its own in java. Instead, it is used to implement a method defined by the functional interface. A lambda expression used with any functional interface and Comparator is a functional interface. The Comparator interface has used when sorting a collection of objects compared with each other.In the below example, we can sort the employee list by name using the Comparator interface.Exampleimport java.util.ArrayList; import java.util.Collections; import java.util.List; class Employee { int id; String name; double salary; public ...
Read MoreWhat is the data type of a lambda expression in Java?
The lambda expressions have a very simple, precise syntax and provide flexibility to specify the datatypes for the function parameters. Its return type is a parameter -> expression body to understand the syntax, we can divide it into three parts.Parameters : These are function method parameters and match with the signature of a function defined in the functional interface. Defining the data-type of parameters is optional but the number of parameters can match with the defined signatures in the interface.Expression Body : This is either a single statement or collection of statements that represent the function definition. Defining the data-type ...
Read MoreWhat is the reason to choose jasmine over jest?
There is no solid reason to choose jasmine over jest. Both are excellent libraries that have been around for a while and have an opinionated way of doing things that are quite similar. Jest is built on top of jasmine.One reason why you might choose jasmine over jest is that it is faster. (https://github.com/facebook/jest/issues/6694)
Read MoreHow to check if element exists in the visible DOM?
We can use the Node.contains method to do this check. The Node.contains() method returns a Boolean value indicating whether a node is a descendant of a given node, i.e. the node itself, one of its direct children (childNodes), one of the children's direct children, and so on.ExampleFor example, you are looking for an element with id test, you can use the following −const elem = document.querySelector('#test'); console.log(document.body.contains(elem));This will log true or false based on whether the element is present in the visible DOM.
Read MoreThe Pros and Cons of Using Ajax
Ajax is a set of web development techniques using many web technologies on the client-side to create asynchronous web applications. With Ajax, web applications can send and retrieve data from a server asynchronously without interfering with the display and behavior of the existing page.Any other technology Ajax also has its own pros and cons. Let's look at some of those.Pros −Allows applications to render without data and fill data as the application gets it from the server.Gives platform independence to application developersFaster page rendersMore responsive applicationsNo rerenders of whole pages are needed to update only a single area.Cons−Any user whose ...
Read MoreHow to Send and Receive JSON Data to and from the Server
JavaScript can send network requests to the server and load JSON. JS does this using something called AJAX. AJAX stands for Asynchronous JavaScript and XML. JS has an API, fetch, to GET(receive) and POST(send) information to the server.You can use fetch to GET JSON data in the following way −Exampleconst URL = 'https://jsonplaceholder.typicode.com/todos/1' // Send a GET request without any data to the server fetch(URL, {method: "GET"}) // Get the JSON data from the raw response .then(res => res.json()) // Print the result .then(console.log)OutputThis will give the output −{ "userId": 1, "id": 1, "title": "delectus ...
Read MoreHow to remove non-ASCII characters from strings
The Posix character class \p{ASCII} matches the ASCII characters and the meta character ^ acts as negation.i.e. The following expression matches all the non-ASCII characters."[^\p{ASCII}]"The replaceAll() method of the String class accepts a regular expression and a replacement-string and, replaces the characters of the current string (matching the given pattern) with the specified replacement-string.Therefore, You can remove the matched characters by replacing them with the empty string “, using the replaceAll() method.Example 1import java.util.Scanner; public class Exp { public static void main( String args[] ) { Scanner sc = new Scanner(System.in); String regex = ...
Read MoreHow to match the regex meta characters in java as literal characters.
The compile method of the patter class accepts two parameters −A string value representing the regular expression.An integer value a field of the Pattern class.The filed LITERAL of the enables literal parsing of the pattern. i.e. all the regular expression metacharacters and escape sequences don’t have any special meaning they are treated as literal characters. Therefore, If you need to match the regular expression metacharacters as normal characters you need to pass this as a flag value to the compile() method along with the regular expression.Exampleimport java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] ...
Read MoreHow match a string irrespective of case using Java regex.
The compile method of the patter class accepts two parameters −A string value representing the regular expression.An integer value a field of the Pattern class.This CASE_INSENSITIVE field of the Pattern class matches characters irrespective of case. Therefore, if you pass as flag value to the compile() method along with your regular expression, characters of both cases will be matched.Example 1import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main( String args[] ) { Scanner sc = new Scanner(System.in); System.out.println("Enter input data: "); String input = sc.nextLine(); ...
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