Selection Sort in Java

Introduction

Sorting data is a frequent problem in computer science. Given a collection of elements, the goal is to rearrange them in some order. Common examples are sorting an array alphabetically or from smallest to largest.

Sorted data is a lot easier to manipulate. Finding the largest or smallest element of an array can be done in constant time if the array is sorted. Searching for an element is a lot faster using algorithms such as Binary Search which rely on the assumption that the array is already sorted.

One of the simplest algorithms for sorting data is Selection Sort. It’s usually taught in beginner programming classes and tutorials to explain the concept of sorting, so we’ll keep this article very beginner-friendly.

#java #selection sort in java #selection sort

What is GEEK

Buddha Community

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

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);

unsortedMap.entrySet().forEach(System.out::println);

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.

HashMaps don’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:

John=21
Mark=31
Maria=34
Sydney=24

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

Selection Sort in Java

Introduction

Sorting data is a frequent problem in computer science. Given a collection of elements, the goal is to rearrange them in some order. Common examples are sorting an array alphabetically or from smallest to largest.

Sorted data is a lot easier to manipulate. Finding the largest or smallest element of an array can be done in constant time if the array is sorted. Searching for an element is a lot faster using algorithms such as Binary Search which rely on the assumption that the array is already sorted.

One of the simplest algorithms for sorting data is Selection Sort. It’s usually taught in beginner programming classes and tutorials to explain the concept of sorting, so we’ll keep this article very beginner-friendly.

#java #selection sort in java #selection sort

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

How to Sort a HashMap by Value in Java

In this tutorial, we’ll take a look at how to sort a HashMap by value 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);

unsortedMap.entrySet().forEach(System.out::println);

We’ve got Strings as keys, and Integers as values. And we’d like to sort this map based on the values.

HashMaps don’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:

John=21
Mark=31
Maria=34
Sydney=24

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.

Note: TreeMap extends the SortedMap interface, unlike the HashMap implementation. TreeMaps are meant to be the sorted counterpart, however, TreeMaps only sort by keys, given a comparator.

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