Malvina  O'Hara

Malvina O'Hara

1601011620

Wrapper Class in Java Example | Java Wrapper Classes

Java Wrapper class is an inbuilt class whose object wraps or contains primitive data types. When we create the object to the wrapper class, it contains the field, and in this field, we can store primitive  data types. In OOPs explanation we learned that object-oriented programming is all about objects and there are eight primitive data types (used as raw data for operations such as arithmetic, logical, etc.,), but they are not objects.

Wrapper Class in Java

Wrapper class in Java is a class that contains and wraps the primitive data types (char, short, bytes, etc.). In other words, wrapper classes provide a way to use primitive data types (int, char, etc…) as objects. This wrapper class comes under java.util package. All the wrapper classes (Integer, Long, etc.) are subclasses of the abstract class Number.

#wrapper class #java #java.util #programming

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Wrapper Class in Java Example | Java Wrapper Classes
Tyrique  Littel

Tyrique Littel

1600135200

How to Install OpenJDK 11 on CentOS 8

What is OpenJDK?

OpenJDk or Open Java Development Kit is a free, open-source framework of the Java Platform, Standard Edition (or Java SE). It contains the virtual machine, the Java Class Library, and the Java compiler. The difference between the Oracle OpenJDK and Oracle JDK is that OpenJDK is a source code reference point for the open-source model. Simultaneously, the Oracle JDK is a continuation or advanced model of the OpenJDK, which is not open source and requires a license to use.

In this article, we will be installing OpenJDK on Centos 8.

#tutorials #alternatives #centos #centos 8 #configuration #dnf #frameworks #java #java development kit #java ee #java environment variables #java framework #java jdk #java jre #java platform #java sdk #java se #jdk #jre #open java development kit #open source #openjdk #openjdk 11 #openjdk 8 #openjdk runtime environment

Lawrence  Lesch

Lawrence Lesch

1662107520

Superdom: Better and Simpler ES6 DOM Manipulation

Superdom

You have dom. It has all the DOM virtually within it. Use that power:

// Fetch all the page links
let links = dom.a.href;

// Links open in a new tab
dom.a.target = '_blank';

Only for modern browsers

Getting started

Simply use the CDN via unpkg.com:

<script src="https://unpkg.com/superdom@1"></script>

Or use npm or bower:

npm|bower install superdom --save

Select

It always returns an array with the matched elements. Get all the elements that match the selector:

// Simple element selector into an array
let allLinks = dom.a;

// Loop straight on the selection
dom.a.forEach(link => { ... });

// Combined selector
let importantLinks = dom['a.important'];

There are also some predetermined elements, such as id, class and attr:

// Select HTML Elements by id:
let main = dom.id.main;

// by class:
let buttons = dom.class.button;

// or by attribute:
let targeted = dom.attr.target;
let targeted = dom.attr['target="_blank"'];

Generate

Use it as a function or a tagged template literal to generate DOM fragments:

// Not a typo; tagged template literals
let link = dom`<a href="https://google.com/">Google</a>`;

// It is the same as
let link = dom('<a href="https://google.com/">Google</a>');

Delete elements

Delete a piece of the DOM

// Delete all of the elements with the class .google
delete dom.class.google;   // Is this an ad-block rule?

Attributes

You can easily manipulate attributes right from the dom node. There are some aliases that share the syntax of the attributes such as html and text (aliases for innerHTML and textContent). There are others that travel through the dom such as parent (alias for parentNode) and children. Finally, class behaves differently as explained below.

Get attributes

The fetching will always return an array with the element for each of the matched nodes (or undefined if not there):

// Retrieve all the urls from the page
let urls = dom.a.href;     // #attr-list
  // ['https://google.com', 'https://facebook.com/', ...]

// Get an array of the h2 contents (alias of innerHTML)
let h2s = dom.h2.html;     // #attr-alias
  // ['Level 2 header', 'Another level 2 header', ...]

// Get whether any of the attributes has the value "_blank"
let hasBlank = dom.class.cta.target._blank;    // #attr-value
  // true/false

You also use these:

  • html (alias of innerHTML): retrieve a list of the htmls
  • text (alias of textContent): retrieve a list of the htmls
  • parent (alias of parentNode): travel up one level
  • children: travel down one level

Set attributes

// Set target="_blank" to all links
dom.a.target = '_blank';     // #attr-set
dom.class.tableofcontents.html = `
  <ul class="tableofcontents">
    ${dom.h2.map(h2 => `
      <li>
        <a href="#${h2.id}">
          ${h2.innerHTML}
        </a>
      </li>
    `).join('')}
  </ul>
`;

Remove an attribute

To delete an attribute use the delete keyword:

// Remove all urls from the page
delete dom.a.href;

// Remove all ids
delete dom.a.id;

Classes

It provides an easy way to manipulate the classes.

Get classes

To retrieve whether a particular class is present or not:

// Get an array with true/false for a single class
let isTest = dom.a.class.test;     // #class-one

For a general method to retrieve all classes you can do:

// Get a list of the classes of each matched element
let arrays = dom.a.class;     // #class-arrays
  // [['important'], ['button', 'cta'], ...]

// If you want a plain list with all of the classes:
let flatten = dom.a.class._flat;     // #class-flat
  // ['important', 'button', 'cta', ...]

// And if you just want an string with space-separated classes:
let text = dom.a.class._text;     // #class-text
  // 'important button cta ...'

Add a class

// Add the class 'test' (different ways)
dom.a.class.test = true;    // #class-make-true
dom.a.class = 'test';       // #class-push

Remove a class

// Remove the class 'test'
dom.a.class.test = false;    // #class-make-false

Manipulate

Did we say it returns a simple array?

dom.a.forEach(link => link.innerHTML = 'I am a link');

But what an interesting array it is; indeed we are also proxy'ing it so you can manipulate its sub-elements straight from the selector:

// Replace all of the link's html with 'I am a link'
dom.a.html = 'I am a link';

Of course we might want to manipulate them dynamically depending on the current value. Just pass it a function:

// Append ' ^_^' to all of the links in the page
dom.a.html = html => html + ' ^_^';

// Same as this:
dom.a.forEach(link => link.innerHTML = link.innerHTML + ' ^_^');

Note: this won't work dom.a.html += ' ^_^'; for more than 1 match (for reasons)

Or get into genetics to manipulate the attributes:

dom.a.attr.target = '_blank';

// Only to external sites:
let isOwnPage = el => /^https?\:\/\/mypage\.com/.test(el.getAttribute('href'));
dom.a.attr.target = (prev, i, element) => isOwnPage(element) ? '' : '_blank';

Events

You can also handle and trigger events:

// Handle click events for all <a>
dom.a.on.click = e => ...;

// Trigger click event for all <a>
dom.a.trigger.click;

Testing

We are using Jest as a Grunt task for testing. Install Jest and run in the terminal:

grunt watch

Download Details:

Author: franciscop
Source Code: https://github.com/franciscop/superdom 
License: MIT license

#javascript #es6 #dom 

Samanta  Moore

Samanta Moore

1621841820

Wrapper Class in Java | Java Wrapper Classes

What is a Wrapper Class in Java?

Java is an object-oriented language that converts a primitive data type into a class object; hence, wrapper class objects enable us to convert the original passed value. These wrapper classes support the multithreading and synchronisation process. With the help of this, we can work with collections like Vector, LinkedList, ArrayList.

Process Flow of the Wrapper Class

In a wrapper class, we create the object with fields or properties, where we can use and store the primitive data types.

Java implements in-built classes corresponding to specific primitive types that can be applied to modify these value types in object types. We can consider and identify these inbuilt classes as wrapper classes or primitive wrapper classes.

Use of Wrapper Class in Java Programming

  • We can use the wrapper class and create a function with parameters using primitive data types.
  • We can change the primitive data type into a distinct wrapper class.
  • Wrapper class allows various methods while using collections like sorting and searching.
  • The wrapper class implements the technique to convert the primitive into object and object into primitive_._
  • There is a concept of autoboxing and unboxing in the wrapper class, which transform the primitives into objects and objects into primitives automatically.
  • In Java, we have a synchronisation mechanism that works with objects in multithreading.

#full stack development #java #wrapper class #wrapper class in java

Joseph  Murray

Joseph Murray

1621634700

Wrapper Class in Java | Java Wrapper Classes

What is a Wrapper Class in Java?

Java is an object-oriented language that converts a primitive data type into a class object; hence, wrapper class objects enable us to convert the original passed value. These wrapper classes support the multithreading and synchronisation process. With the help of this, we can work with collections like Vector, LinkedList, ArrayList.

Process Flow of the Wrapper Class

In a wrapper class, we create the object with fields or properties, where we can use and store the primitive data types.

Java implements in-built classes corresponding to specific primitive types that can be applied to modify these value types in object types. We can consider and identify these inbuilt classes as wrapper classes or primitive wrapper classes.

#full stack development #java #wrapper class #wrapper class in java

Malvina  O'Hara

Malvina O'Hara

1601011620

Wrapper Class in Java Example | Java Wrapper Classes

Java Wrapper class is an inbuilt class whose object wraps or contains primitive data types. When we create the object to the wrapper class, it contains the field, and in this field, we can store primitive  data types. In OOPs explanation we learned that object-oriented programming is all about objects and there are eight primitive data types (used as raw data for operations such as arithmetic, logical, etc.,), but they are not objects.

Wrapper Class in Java

Wrapper class in Java is a class that contains and wraps the primitive data types (char, short, bytes, etc.). In other words, wrapper classes provide a way to use primitive data types (int, char, etc…) as objects. This wrapper class comes under java.util package. All the wrapper classes (Integer, Long, etc.) are subclasses of the abstract class Number.

#wrapper class #java #java.util #programming