Samanta  Moore

Samanta Moore


Mastering How to Work with HashMap and ArrayList in JAVA 2021

Learn Mastering How to Work with HashMap and ArrayList in JAVA 2021


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Mastering How to Work with HashMap and ArrayList in JAVA 2021
Tyrique  Littel

Tyrique Littel


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

Joseph  Murray

Joseph Murray


Internal Working of HashMap in Java

Know your next interview question.

I have seen a lot of interviewers asking for the internal working mechanism of the hashmap. If you know the complete internal working of one of the map implementations, it becomes easier for you to understand the other classes of the map interface.So thru this article, we’ll see how the hashing is done and its complete working mechanism, how the searchinsert and removeoperations work with the hashmap and their time complexities, and at the end, we’ll see why it should not be used in a multi-threading environment.

What is HashMap?

How to Initialize the Constructor with Our Own Capacity and Load factor?

Frequently Used Hashmap Methods:

Let’s See an Example of Hashmap and Its Functions:

#java #software-development #programming #internal working of hashmap in java #hashmap #internal working

How to Sort a HashMap by Key in Java

In this tutorial, we’ll take a look at how to sort a HashMap by key in Java.

Let’s go ahead and create a simple HashMap:

Map<String, Integer> unsortedMap = new HashMap();

unsortedMap.put("John", 21);
unsortedMap.put("Maria", 34);
unsortedMap.put("Mark", 31);
unsortedMap.put("Sydney", 24);


We’ve got Strings as keys, and Integers as values. Most of the time, you’ll encounter Integers or Strings as keys, and custom objects, Strings or Integers as values. We’ll want to sort this HashMap, based on the String keys.

HashMapdon’t guarantee to maintain the order of its elements in any case. The order can change through time, and they most definitely won’t be printed back in the order of insertion:


If you re-run this program, it’ll keep this order, since HashMaps order their elements into bins, based on the hash value of the keys. When printing values from a HashMap, its contents are printed sequentially, so the results will stay the same if we re-run the program multiple times.

#java #how to sort a hashmap by key in java #hashmap #key in java #sort #sort a hashmap by key in java

Samanta  Moore

Samanta Moore


Going Beyond Java 8: Local Variable Type Inference (var) - DZone Java

According to some surveys, such as JetBrains’s great survey, Java 8 is currently the most used version of Java, despite being a 2014 release.

What you are reading is one in a series of articles titled ‘Going beyond Java 8,’ inspired by the contents of my book, Java for Aliens. These articles will guide you step-by-step through the most important features introduced to the language, starting from version 9. The aim is to make you aware of how important it is to move forward from Java 8, explaining the enormous advantages that the latest versions of the language offer.

In this article, we will talk about the most important new feature introduced with Java 10. Officially called local variable type inference, this feature is better known as the **introduction of the word **var. Despite the complicated name, it is actually quite a simple feature to use. However, some observations need to be made before we can see the impact that the introduction of the word var has on other pre-existing characteristics.

#java #java 11 #java 10 #java 12 #var #java 14 #java 13 #java 15 #verbosity

Joseph  Murray

Joseph Murray


7 Test Frameworks To Follow in 2021 for Java/Fullstack Developers

It is time to learn new test frameworks in 2021 to improve your code quality and decrease the time of your testing phase. Let’s explore 6 options for devs.

It is time to learn new test frameworks to improve your code quality and decrease the time of your testing phase. I have selected six testing frameworks that sound promising. Some have existed for quite a long time but I have not heard about them before.

At the end of the article, please tell me what you think about them and what your favorite ones are.

Robot Framework

Robot Framework is a generic open-source automation framework. It can be used for test automation and robotic process automation (RPA).

Robot Framework is open and extensible and can be integrated with virtually any other tool to create powerful and flexible automation solutions. Being open-source also means that Robot Framework is free to use without licensing costs.

The RoboFramework is a framework** to write test cases and automation processes.** It means that it may replace** your classic combo Selenium + Cucumber + Gherkins**. To be more precise, the Cucumber Gherkins custom implementation you wrote will be handled by RoboFramework and Selenium invoked below.

For the Java developers, this framework can be executed with Maven or Gradle (but less mature for the latter solution).

#java #testing #test #java framework #java frameworks #testing and developing #java testing #robot framework #test framework #2021