Setting up Java Development Environment

October 17, 2020

Before you start developing code in Java, you need to setup your development environment with the necessary development tools required to build, compile, test and execute your java code.

Base Requirements

• Operating System: This is the core and starting block. If you are reading this post, you already have one. May be Windows, Linux or Mac OS
• Java Development Kit(JDK): This is the foundation and building block of other tools required to write your java code and also it’s ecosystem. You can download your JDK Here
• Build/project management tools: While not compulsory, this will make your life so much easier and stress free.
  • Maven: Maven helps and simplifies the build process. You can download Maven Here.
  • Gradle: Gradle is another tool available for the build process. You can download Maven Here. Personally, I prefer Maven. It’s XML based and works great. Just my personal preference.
• Integrated Development Environment (IDE): A IDE helps with code entry and also glues your other tools under the hood. A lot of them come with debuggers also. You have lots of options here. IntelliJ Idea from Jetbrains, Eclipse, NetBeans etc. Try them out and stick with one you are comfortable with.
• Git: Git is used for version control. This is essential and I recommend using this as much as possible.

Setup

This setup is geared towards linux systems and assumes a basic level of systems administration.

• Download JDK and Maven and untar them in your opt directory.
• Setup your systems profile and path. For the purpose of this post, my /etc/profile setup looks like this

  export JAVA_HOME="/opt/jdk-15"
  export M2_HOME="/opt/apache-maven"
  export MAVEN_HOME="/opt/apache-maven"
  export PATH=$JAVA_HOME/bin:$PATH
  export PATH=${M2_HOME}/bin:${PATH}
  

  When this is completed, test your setup. source /etc/profile. Check your java version with this command java -version. You should see this

  openjdk version "15" 2020-09-15
  OpenJDK Runtime Environment (build 15+36-1562)
  OpenJDK 64-Bit Server VM (build 15+36-1562, mixed mode, sharing)
  

  Also test Maven. mvn --version. You should see this:

  Apache Maven 3.6.3 (cecedd343002696d0abb50b32b541b8a6ba2883f)
  Maven home: /opt/apache-maven
  Java version: 15, vendor: Oracle Corporation, runtime: /opt/jdk-15
  Default locale: en_US, platform encoding: UTF-8
  OS name: "linux", version: "4.19.0-11-amd64", arch: "amd64", family: "unix"
  

  If you can see the above, you are ready to begin your Java Development Journey

HelloWorld

Any programming tutorial will not be complete without the famous “HelloWorld”. We will generate one with some added features and functionality.

• Create Project using MAVEN

  mvn archetype:generate -DgroupId=com.javaconcepts.app -DartifactId=javaconcepts -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false
  

  Change directory cd javaconcepts and update your pom.xml file with the code below:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.javaconcepts.app</groupId>
  <artifactId>javaconcepts</artifactId>
  <packaging>jar</packaging>
  <version>1.0-SNAPSHOT</version>

  <properties>
    <maven.compiler.source>1.7</maven.compiler.source>
    <maven.compiler.target>1.7</maven.compiler.target>
  </properties>

  <name>javaconcepts</name>
  <url>http://maven.apache.org</url>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
  </dependencies>

  <build>
    <plugins>
        <plugin>
            <artifactId>maven-assembly-plugin</artifactId>
            <configuration>
                <archive>
                    <manifest>
                        <mainClass>com.javaconcepts.app.App</mainClass>
                    </manifest>
                </archive>
                <descriptorRefs>
                    <descriptorRef>jar-with-dependencies</descriptorRef>
                </descriptorRefs>
            </configuration>
        </plugin>
    </plugins>
  </build>

</project>

• Update the base app src/main/java/com/javaconcepts/app/App.java with code below:

package com.javaconcepts.app;

public class App 
{
    public static void main(String[] args)
    {
        App2 newapp = new App2();
        System.out.println("Hello World!");
        System.out.println("Welcome to my first App");
        newapp.displayName();        
    }
}

and create a second one src/main/java/com/javaconcepts/app/App2.java with code below:

package com.javaconcepts.app;

public class App2 
{
    public void displayName()
    {
        System.out.println("Welcome to my second class");
    }
}

• Compile and run with the commands

  mvn clean install assembly:single
  java -jar target/javaconcepts-1.0-SNAPSHOT-jar-with-dependencies.jar
  

  If everything goes well, you should see this:

  Hello World!
  Welcome to my first App
  Welcome to my second class
  

  And that is it

Remarks

I tried to address a few things here.

• Show how to use Maven for basic command line project scaffolding
• How to update project pom file to achieve executable JAR
• How to call a class from a main class. This primarily serves as a base reminder when I am working with JAVA.