Core Java APIs and programming techniques

Technologies related to Java APIs (application programming interfaces) and JDK (Java Development Kit) form the cornerstone of modern, enterprise-grade software development. Here we explore all the Java features that make the JVM great through programming tutorials, real-world code samples and expert opinions from Java champions.

Top Stories

Video 10 May 2024
Java records tutorial

Java is constantly evolving, but some changes are more significant than others. This Java records tutorial teaches you about this decade's largest language enhancement to date. Continue Reading
Video 01 May 2024
Java's default constructor tutorial

They say you don't get anything for free, but in the world of software development, Java developers can use the default constructor without paying any price. Continue Reading

Tip 01 May 2024

Use sealed classes in Java to control your inheritance

Need to limit the number of possible subclasses in your codebase? Here comes Java's sealed classes to your rescue. Continue Reading
Tip 29 Apr 2024

Know how and when to use blockchain vs. distributed ledgers

Blockchain and distributed ledgers are similar but not quite synonymous. Learn their differences and how they are used, including together, for transactions and data storage. Continue Reading
Tip 11 Apr 2024

Speed up Python and NumPy by avoiding the conversion tax

Data and memory transfers in Python come with a hidden performance tax. Here's how to use NumPy for optimal performance by avoiding jumps across a hidden line of conversions. Continue Reading
Tip 09 Apr 2024

5 code refactoring patterns, with examples

First-time finished code is rarely elegant or maintainable. Refactoring helps keep a growing codebase maintainable and extendable over time -- as long as you know where to stop. Continue Reading
Video 09 Apr 2024

Top REST API URL naming convention standards

There is no official REST URL naming standard. However, these 15 RESTful API naming conventions will help you create highly interoperable web services. Continue Reading
Blog Post 08 Apr 2024

Worlds toughest core Java interview question

The trickiest Java interview question ever asked? In five words or less, explain the red 'x' the Eclipse IDE displays at the end of the provided Java code snippet. Continue Reading
Video 04 Apr 2024

10 constructor types in Java

How many different types of Java constructors could you name? The Java spec names 10. Generic, canonical and anonymous Java constructor types just might be new to you. Continue Reading
Video 04 Apr 2024

How Java 17 records work

Devs aren't using Java 17 records nearly enough. With the power to clean up your code and make your apps faster, Java records should be the norm and not the exception. Continue Reading
Video 01 Apr 2024

How to use Git's 'set upstream push' command

Need to fix the 'no upstream branch' error message? Then you need to run the 'git set upstream push' command. Here's how. Continue Reading
Tutorial 27 Mar 2024

How the saga design pattern in microservices works

When a sequence of steps must be performed to support an operation, the microservices saga design pattern is a perfect fit. Continue Reading
Definition 25 Mar 2024

Spring Framework (Spring)

The Spring Framework (Spring) is an open source software development framework that provides infrastructure support for building Java-based applications on any deployment platform. Continue Reading
Video 19 Mar 2024

Learn Maven tutorial for beginners

Apache Maven is the Java world's most popular build tool, and if you're a Java developer, it behooves you to learn it. This Maven tutorial will make you an expert in a hurry. Continue Reading
Video 12 Mar 2024

Full Java constructors tutorial

How well do you know how Java constructors work? This quick Java constructors tutorial teaches you about defaults, overloading, initializing and parameterizing constructors in Java. Continue Reading
Definition 05 Mar 2024

EAI (enterprise application integration)

Enterprise application integration (EAI) is the process of connecting an organization's business applications, services, databases and other systems into an integrating framework that facilitates communications and interoperability. Continue Reading
Blog Post 04 Mar 2024

Best crash course to learn Jenkins from scratch

Need to learn Jenkins CI fast? This Jenkins tutorial will quickly get you up to speed on how to use the popular CI/CD tool. Continue Reading
Blog Post 27 Feb 2024

Brackets vs braces vs parentheses: What's the difference?

Stop using the terms square brackets, round brackets and squiggly brackets. Use the terms braces, brackets and parenthesis instead. Here's the difference between them. Continue Reading
Video 22 Feb 2024

Why we use static final in Java for constants

Java doesn't have global constants per se, but it does have static final variables. Here we explore how these two keywords make a variable constant in Java. Continue Reading
Definition 15 Feb 2024

event handler

In programming, an event handler is a callback routine that operates asynchronously once an event takes place. Continue Reading
Blog Post 14 Feb 2024

String to long in Java

The correct way to convert a String to long in Java is with the parseLong method of the wrapper class. The constructor conversion approach is deprecated! Use parseLong instead. Continue Reading
Blog Post 02 Feb 2024

How to unstage a file in Git

Want to unstage a file in Git? Use the restore command. Other options to have Git remove a file from the staging index have unintended consequences you'd really rather avoid. Continue Reading
Blog Post 01 Feb 2024

Why the Java const keyword is unimplemented

Why is the const keyword in Java not implemented? It's part of the language, but it can't be used to make a variable constant. Here's why const is included in Java, and why Java's const keyword is ... Continue Reading
Tip 30 Jan 2024

2024 technology predictions around AI, Mojo and blockchain

Blockchain, AI, anti-competitive activity and the new programming language Mojo are sure to fill the headlines in 2024. Continue Reading
Tip 23 Jan 2024

Debunking 5 blockchain myths and misconceptions

There's more to blockchain development than what you hear from the crypto community. Here, we debunk five common blockchain myths. Continue Reading
Blog Post 18 Jan 2024

Finding duplicate entries in a list in Python

A common problem in computing is to find out if a list contains duplicate entries. It's also a good subject to explore various ways to solve a problem. In this case, we will see the performance ... Continue Reading
Blog Post 17 Jan 2024

Solve the prefix sum problem with SIMDs and Vector APIs

The incubating Java Vector API gives software developers access to fast and efficient SIMD operations. Here's an example of how to solve the prefix sum problem with SIMDs and Vectors. Continue Reading
Blog Post 11 Jan 2024

How to download and install Java 21

2024 is a great time to start working with Java, because 2023's Java 21 release has some amazing new features. Here's how to quickly download and install the Java 21 JDK. Continue Reading
Blog Post 09 Jan 2024

Install the Eclipse IDE on Windows video tutorial

Need to install the Eclipse IDE on Windows? This quick video tutorial shows you how to install Eclipse and build your very first Java application in the popular, open-source IDE. Continue Reading
Blog Post 09 Jan 2024

Find duplicates in a List in Java

Need to dedupe a Java list? Here are 5 simple ways to remove duplicates from a List in Java. Continue Reading
Blog Post 08 Jan 2024

The prefix sum array problem

The prefix sum problem is often used to test a developer's mettle. Here's a simple solution to the prefix sum problem in Java that uses loops, arrays and basic Java syntax. Continue Reading
Tip 04 Jan 2024

How the event sourcing design pattern works, with example

Learn how to control state changes as immutable events through the event sourcing model. Continue Reading
Tip 28 Dec 2023

The benefits of using compiled regex in Python and Java

Whether you're programming in Java or Python, compiled regex can significantly speed up your text manipulation routines. Continue Reading
Tip 27 Dec 2023

Shorter code, fewer bugs: Python's syntax is its saving grace

Is shorter code too dense and hard to parse, or is it inherently more efficient and secure? Here's why Python's compact syntax tends toward less buggy code. Continue Reading
Blog Post 27 Dec 2023

Remove duplicates from a Java List

Deduping is a common part of data cleansing. Here are four simple ways to remove duplicates from lists in Java. Continue Reading
Feature 19 Dec 2023

The 5 SOLID principles of object-oriented design explained

In this primer on SOLID, we'll examine the five principles this development ideology embodies, the practices they encourage and the reasons these concepts matter. Continue Reading
Blog Post 06 Dec 2023

How the Actor Model works by example

For enterprise systems that need a flexible, asynchronous and message driven architecture, the Actor Model is often the right fit. Continue Reading
Tip 05 Dec 2023

A primer on Java 21 virtual threads with examples

Virtual threads let developers build applications that handle potentially millions of users and ensure consistent service delivery. Here's how Java 21 virtual threads work. Continue Reading
Answer 01 Dec 2023

11 real benefits of microservices

There's a reason why so many vendors have moved from monoliths to microservices. Here are 11 real benefits microservices bring to companies. Continue Reading
Answer 16 Nov 2023

10 disadvantages of microservices you'll need to overcome

Not everyone is keen to adopt a cloud-native architecture, for good reasons. These common drawbacks to microservices might convince you to stick with your traditional architecture. Continue Reading
Tip 19 Oct 2023

Understanding protocol buffers vs. JSON

Protocol buffers have some compelling advantages over JSON when it comes to sending data between internal services. But is it really a replacement for JSON? Continue Reading
Tip 04 Oct 2023

9 tips to improve Python performance

Python performance gets a bad rap compared with languages such as Java. Use these tips to identify and fix problems in your Python code to tweak its performance. Continue Reading
Blog Post 18 Sep 2023

Java vs. Python: Application code comparison

When you compare Java vs. Python application development in terms of simplicity, conciseness, security and performance, Java comes out on top in every category. Continue Reading
Definition 12 Sep 2023

model-view-controller (MVC)

In programming, model-view-controller (MVC) is an architectural design pattern that organizes an application's logic into distinct layers, each of which carries out a specific set of tasks. Continue Reading
Blog Post 01 Sep 2023

How to discard local changes in Git

Don't overlook a file or two when you attempt to remove and discard local, uncommitted changes in Git. Learn how to locally revert and remove uncommitted changes to files in Git properly. Continue Reading
Blog Post 30 Aug 2023

10 reasons to use Kotlin

Curious about the Kotlin language? It's an excellent choice as either a companion or alternative to Java, and offers many capabilities Java programmers wish they had all along. Continue Reading
Definition 30 Aug 2023

thread

A thread is, fundamentally, a clear, well-defined theme, subject, topic or focus. Continue Reading
Blog Post 24 Aug 2023

How to install Jenkins on Windows

With the Jenkins installer it's incredibly easy to download and run the popular CI/CD tool. Follow these simple steps and you'll have the continuous integration server running on Windows in no time. Continue Reading
Blog Post 21 Aug 2023

HTTP request methods explained

While there are almost 40 registered HTTP request methods, most RESTful web developers only use five of them. Here are the most important HTTP methods and examples of how to use them. Continue Reading
Blog Post 21 Aug 2023

PUT vs POST: What's the difference?

What's the difference between PUT and POST methods? Here we compare POST versus PUT in terms of idempotence, URL usage, payloads and their use in RESTful APIs. Continue Reading
Tutorial 11 Aug 2023

Understanding TypeScript generics

Programming languages such as Java, C# and Swift use generics to create code that's reusable and enforce type safety. In this tutorial, learn how generics in TypeScript work. Continue Reading
Blog Post 07 Aug 2023

How to login to Docker with a Docker Hub access token

Have you been snared by Docker's "unauthorized: incorrect username or password" error when you login at the command line? Here's how to generate an access token in Docker Hub and fix it. Continue Reading
Blog Post 06 Aug 2023

Get started with Spring Boot 3 tutorial

Need to learn Spring Boot 3? Want to quickly build a Spring Boot app with RESTful web services? This tutorial will help you create your first Spring Boot application in just minutes. Continue Reading
Tip 21 Jul 2023

The dangers of Python import and how enterprises can be safe

The Python import statement carries a security risk that developers and enterprises need to watch out for. Here's how it works and why there's no easy fix. Continue Reading
Blog Post 19 Jul 2023

Sprint vs Scrum: What's the difference?

The comparison of Scrum versus a sprint is less about differences and more about how Agile frameworks such as Scrum, SAFe and XP use short development cycles to limit risk and keep stakeholders ... Continue Reading
Blog Post 13 Jul 2023

How to enable Java 21 preview features

Java 21 includes numerous highly anticipated preview features including String templates, scoped variables and unnamed classes. Here's how to enable Java 21 preview features on your JDK. Continue Reading
Definition 13 Jul 2023

Remote Method Invocation (RMI)

Remote Method Invocation (RMI) is an application programming interface (API) in the Java programming language and development environment. Continue Reading
Tutorial 12 Jul 2023

Understanding the TypeScript method decorator

This tutorial explores TypeScript method decorators, reusable code similar to Java annotations that lets developers apply logic in a declarative manner at design time. Continue Reading
Definition 10 Jul 2023

Java Mission Control

Java Mission Control is a performance-analysis tool that renders sampled JVM metrics in easy-to-understand graphs, tables, histograms, lists and charts. Continue Reading
Blog Post 10 Jul 2023

Scrum's chicken and pigs parable

In a ham and eggs breakfast, the chicken is involved, but the pig's 100% committed. That's the problematic basis of Scrum's chicken and pigs parable. Continue Reading
Definition 10 Jul 2023

snake case

Snake case is a naming convention where a developer replaces spaces between words with an underscore. Continue Reading
Blog Post 03 Jul 2023

Create your first Java AWS Lambda function in minutes

If you haven't created a Java-based AWS Lambda function before, you'll be amazed at how easy it is. This quick AWS, Lambda and Java tutorial will quickly get you started in the world of serverless ... Continue Reading
Blog Post 01 Jul 2023

The var keyword in Java

While the use of var in Java brings inferred typing to the platform, it does not negate Java's dedication to strong typing. Here's how the Java var keyword works, along with simple examples of how ... Continue Reading
Tip 30 Jun 2023

How to apply the open-closed principle in Java

How does the open-closed SOLID principle work in a Java program? Here we show you what this important principle means, and how to implement the open-closed principle in Java. Continue Reading
Definition 27 Jun 2023

pseudocode

Pseudocode is a detailed yet readable description of what a computer program or algorithm should do. Continue Reading
Quiz 20 Jun 2023

10 WebAssembly questions to test your Wasm knowledge

Test your knowledge of WebAssembly with this tough, ten-question quiz on the benefits and applications of the new Wasm standard. Continue Reading
Definition 19 Jun 2023

requirements analysis (requirements engineering)

Requirements analysis (requirements engineering) is the process of determining user expectations for a new or modified product. Continue Reading
Definition 12 Jun 2023

lambda

Lambda, the 11th letter of the Greek alphabet, is used as both a symbol and a concept in various fields of science, mathematics and computing. Continue Reading
Blog Post 06 Jun 2023

How Java instance main methods and unnamed classes work

Say goodbye to the public static void main method in Java 21 with the unnamed classes and instance main methods preview features. Continue Reading
Blog Post 04 Jun 2023

Hibernate and JPA column mapping with annotations

Effective Hibernate and JPA column mapping requires the use of the @Column annotation to set important properties such as nullability, uniqueness, precision and scale. Continue Reading
Blog Post 01 Jun 2023

How System.out in Java works

New developers are often confused by the line of System.out.println() code they write when first introduced to Java. Here's a quick explanation of what System.out.println() means. Continue Reading
Blog Post 01 Jun 2023

How to use native SQL in Hibernate and JPA

Need to use raw SQL with JPA and JPA? The Jakarta Persistence API's NativeQuery interface makes it possible to use Hibernate, SQL and JPA together in the same app. Continue Reading
Blog Post 31 May 2023

Java's print vs println method: What's the difference?

What's the difference between print and println methods in Java? Our examples show that it comes down to the fact that println adds a newline character to output, while Java's print method does not. Continue Reading
Definition 31 May 2023

tuple

A tuple, pronounced TUH-pul, is an ordered and finite list of elements in various fields of interest, including computing. Continue Reading
Definition 22 May 2023

API security

Application program interface (API) security refers to policies and procedures that protect APIs against malicious attacks and vulnerabilities. Continue Reading
Definition 19 May 2023

no op (no operation)

No op means 'no operation,' which is a computer instruction that specifies no operation but takes up a small amount of storage space. Continue Reading
Definition 16 May 2023

Unicode

Unicode is a universal character encoding standard that is maintained by the Unicode Consortium, a standards organization founded in 1991 for the internationalization of software and services. Continue Reading
Blog Post 15 May 2023

Hibernate and JPA 3 CRUD example

Struggling to get your first JPA 3 application off the ground? Here's a quick Hibernate and JPA 3 CRUD example to help you get going with the latest version of the Java Persistence API. Continue Reading
Tip 09 May 2023

How to address Python performance problems

Python is a great language for nonprogrammers to do mathematical and scientific tasks, even if such optimization impacts performance. Here's why that's not a fair criticism. Continue Reading
Blog Post 01 May 2023

The right MySQL persistence.xml example file for JPA 3 and Hibernate 6

A quick migration from JPA 2.x to 3.x can become bottlenecked if the persistence.xml file is misconfigured. Here's what a proper persistence.xml file for JPA 3, Hibernate 6 and a MySQL database ... Continue Reading
Blog Post 30 Apr 2023

How to write your first Java program

Want to learn to code and write your first Java program? Here's a quick and fun Java programming tutorial that will have your running your first Java program in less than 10 minutes. Continue Reading
Blog Post 25 Apr 2023

Hello World in Python vs Java

'Hello World' is a silly criterion to use when comparing programming languages. Yet here we are, comparing 'Hello World' in Java vs Python. We'll let you judge the winner. Continue Reading
Tip 31 Mar 2023

JavaScript vs. TypeScript: What's the difference?

TypeScript and JavaScript are two complementary technologies that are driving both front-end and back-end development. Here are the similarities and differences between the two. Continue Reading
Tip 30 Mar 2023

How to apply the single responsibility principle in Java

How does the single responsibility model work in a Java program? Here we show you what this SOLID principle means, and how to implement the single responsibility model in Java. Continue Reading
Blog Post 29 Mar 2023

Why is the Bootstrap grid system 12 columns wide?

Ever wonder why they created a 12-column Bootstrap grid system, and not 10 or 15? It's the same reason there's 60 seconds in a minute, or 360 degrees in a circle. Continue Reading
Blog Post 28 Mar 2023

There's a new Java build system named Bld

Want to write your software build logic entirely in Java? A new build tool called Bld does exactly that, and Geert Bevin and Erik Thauvin are behind it. Continue Reading
Definition 28 Mar 2023

object-relational mapping (ORM)

Object-relational mapping (ORM) is a way to align programming code with database structures. Continue Reading
Blog Post 19 Mar 2023

Critical Java JVM options and parameters

The easiest way to optimize your Java runtime is to supply correct JVM options and parameters. In honor of the Java 21 release, we examine the 21 most important Java JVM options you can configure. Continue Reading
Blog Post 04 Mar 2023

Real world Java applications

Java runs on billions of devices, and Java applications of importance run on systems all over the world. Here are the top 10 applications of Java technology today, plus a look at what the future ... Continue Reading
Blog Post 28 Feb 2023

Top 10 software myths debunked

Software myths abound in the IT industry. Here are the top 10 software devlepment myths and misconceptions, along with a full debunking of these mythical ideas. Continue Reading
Blog Post 26 Feb 2023

How to use JShell in Java

If you haven't used Java's JShell yet, you're missing out. Here's a quick Java and JShell tutorial to get you started. Continue Reading
Definition 22 Feb 2023

abstract class

An abstract class is a template definition of methods and variables in a specific class, or category of objects. Continue Reading
Tip 15 Feb 2023

Why Java in 2023?

Has there ever been a better time to be a Java programmer? From new Spring releases to active JUGs, the Java platform is experiencing a renaissance. Continue Reading
Tip 27 Jan 2023

How developers can avoid remote work scams

Software developers can find good remote programming jobs, but some job offers are too good to be true. Follow these tips to spot remote job scams. Continue Reading
Tip 12 Jan 2023

Tips and tricks for TypeScript programming

For those new to TypeScript or for Java developers transitioning into JavaScript, these three TypeScript tips and tricks modern day software developers will come in handy. Continue Reading
Tutorial 06 Jan 2023

11 lessons learned from writing my first Java program

You'll be amazed how easy it is to learn Java and write powerful cross-platform applications when writing your first Java program. Some misconceptions about Java just aren't true. Continue Reading
Blog Post 04 Dec 2022

How do you say Udemy? The 11 most mispronounced tech terms

How do you say Udemy? How do you pronounce JSON or GIF? There's a right way and there's a wrong way. Learn the right way to say these commonly mispronounced tech terms. Continue Reading
Tip 25 Oct 2022

The differences between Java and TypeScript devs must know

Do you know Java? Are you trying to learn TypeScript? Here are five differences between TypeScript and Java that will make the learning transition easier. Continue Reading
Tutorial 29 Sep 2022

Your top 4 Java user input strategies

From System.in to the Scanner class, there are many ways to read user input into your Java programs. Find out which Java user input strategy is best for your software needs. Continue Reading
Tutorial 29 Sep 2022

How Java's System.in reads input from the user

The Java System.in component provides universal access to console-based user input. Learn how to make your applications interactive with this Java System.in tutorial. Continue Reading
Blog Post 09 Sep 2022

Java Exception handling best practices

Don't let the complexities of Java Exception handling get you down. Follow these top 10 Java Exception handling examples and you'll be an expert in handling errors in your Java code. Continue Reading
Definition 26 Aug 2022

Java string

A Java string is a sequence of characters that exists as an object of the class java.lang. Continue Reading