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README.md

Setting up a Java project using IntelliJ IDEA

A Java project set up using IntelliJ IDEA

Introduction

With this part of the Java challenges project, I provide the code and settings for a Java project set up using IntelliJ IDEA.

Below, I give background information on the project’s code and IntelliJ IDEA’s configuration. I also discuss issues that can occur when setting up a Java project using IntelliJ IDEA.

1. Background

1.1 Java

This project makes use of Java. I describe this programming language in the Java section of the Java challenges project.

1.1.1 Code

For demonstrative purposes, the current project contains only a single Java class called Main, which consists of a main method outputting a well-known message:

package nl.mauritssilvis.challenges.java.intellij.manual.projects.basic;

public class Main {
    public static void main(String[] args) {
        System.out.println("Hello world!");
    }
}

1.2 IntelliJ IDEA

This project is set up using IntelliJ IDEA (see, e.g., the IntelliJ IDEA section of the Java challenges project).

The IntelliJ IDEA configuration is described in what follows.

1.2.1 Configuration

The .idea folder of this project contains several IntelliJ-IDEA-related configuration files. A few of these files are highlighted below.

Code styles

First, Unix-style line endings are selected in the file Project.xml, which facilitates cross-platform coding. In addition, rulers are shown at 80 characters:

<component name="ProjectCodeStyleConfiguration">
  <code_scheme name="Project" version="173">
    <option name="LINE_SEPARATOR" value="&amp;#10;" />
    <option name="SOFT_MARGINS" value="80" />
  </code_scheme>
</component>
Copyright

Automatic copyright messages, including the current year and an SPDX license identifier for the GNU General Public License v3.0, are configured in the file GNU_GPL_v3.xml:

<component name="CopyrightManager">
  <copyright>
    <option name="notice" value="Copyright © &amp;#36;today.year Maurits Silvis&#10;SPDX-License-Identifier: GPL-3.0-or-later" />
    <option name="myName" value="GNU GPL v3" />
  </copyright>
</component>
Inspection profiles

A code inspection profile in which all Java-21-compatible IntelliJ IDEA inspections are turned on is provided in All.xml. This profile facilitates learning about possible code improvements and optimizations. A profile in which only the default inspections are selected is stored in Default.xml.

Run configurations

This project comes with a run configuration for executing the main method of the Main class.

Java Development Kit

This project is configured to run with the Adoptium distribution of the Java Development Kit (JDK) 21. This setting can be reviewed in IntelliJ IDEA’s project settings or the file misc.xml.

2. Issues and solutions

While setting up and executing a Java project using IntelliJ IDEA, you may encounter several issues. Below, I discuss problems related to the configuration of IntelliJ IDEA.

2.1 Configuration issues

2.1.1 Project JDK is not defined / JDK "temurin-21" is missing

When you open this project, IntelliJ IDEA may show one or more of the following warnings:

Project JDK is not defined

JDK "temurin-21" is missing

To solve these warnings and be able to execute the project’s code, configure the project JDK in IntelliJ IDEA’s project settings. You can either select one of the listed JDKs or opt for the Adoptium distribution of the Java Development Kit (JDK) by following the Installation section of Setting up a Java project using the command line and selecting that JDK.

License

Copyright © 2021–2023 Maurits Silvis

This source code package is subject to the terms and conditions defined in the GNU General Public License v3.0 or later.