How To Install OpenJDK 16 On Ubuntu 20.04 LTS

How To Install OpenJDK 16 On Ubuntu 20.04 LTS

It provides all the steps required to install OpenJDK 16 on Ubuntu 20.04 LTS and getting started with Java development using the Hello World example.

March 31, 2021

This tutorial provides all the steps required to install OpenJDK 16 on the popular Linux distribution i.e. Ubuntu. It provides all the steps for Ubuntu 20.04 LTS (Focal Fossa). The steps should be the same for other versions of Ubuntu, and Linux.

You can also follow the steps to install How To Install VSCode For Java On Ubuntu, How To Install IntelliJ IDEA for Java on Ubuntu, and How To Install Eclipse For Java Development On Ubuntu published by Tutorials24x7. You may also follow the How To Install OpenJDK 16 On Windows to install the latest OpenJDK on Windows and How To Install Java 16 On Windows to install Oracle JDK.

Download JDK

Open the JDK 16 GA Release site and download the distribution for Linux systems as highlighted in Fig 1.

Install OpenJDK 16 On Ubuntu 20.04 LTS - Download Options

Fig 1

Install JDK

Open the terminal and make the directory /usr/java/openjdk to keep all the java installations at the same place. We can install multiple versions of Java in this directory. Now copy the downloaded file to this location and extract it as shown below:

>sudo mkdir -p /usr/java/openjdk
>cd /usr/java/openjdk
>sudo cp /data/setups/openjdk-16_linux-x64_bin.tar.gz openjdk-16_linux-x64_bin.tar.gz
>sudo tar -xzvf openjdk-16_linux-x64_bin.tar.gz

The above steps will install JDK to the path /usr/java/openjdk/jdk-16.

Set Environment Variables

In this step, we will configure the environment variable to use the JDK installed by us.

>sudo nano /etc/profile

Scroll down by pressing Page Down Button and add at the end of this file:

# OpenJDK 16
JAVA_HOME=/usr/java/openjdk/jdk-16
PATH=$PATH:$HOME/bin:$JAVA_HOME/bin
export JAVA_HOME
export PATH

Now press Ctrl + O and press Enter to write our change. Press Ctrl + X to exit the nano editor. The nano editor should be similar to Fig. 2.

Install OpenJDK 16 On Ubuntu 20.04 LTS - Environment Path

Fig 2

Configure Java Commands

We can configure the Java commands to use the newly installed JDK by default. We can check the installed Java before and after executing these commands as shown below:

In case JDK is already installed on the system, it should show existing JDK as shown below.

# Check version
java -version

# Output
java version "16" 2021-03-16
Java(TM) SE Runtime Environment (build 16+36-2231)
Java HotSpot(TM) 64-Bit Server VM (build 16+36-2231, mixed mode, sharing)

It shows that Oracle JDK 16 was installed on my system. In case JDK is not installed on your system, the messages should be similar as shown below.

# Check version
java -version
# Output
Command 'java' not found, but can be installed with:

sudo apt install openjdk-11-jre-headless # version 11.0.8+10-0ubuntu1~20.04, or
sudo apt install default-jre # version 2:1.11-72
sudo apt install openjdk-13-jre-headless # version 13.0.3+3-1ubuntu2
sudo apt install openjdk-14-jre-headless # version 14.0.1+7-1ubuntu1
sudo apt install openjdk-8-jre-headless # version 8u265-b01-0ubuntu2~20.04

If JDK is not installed on your system, use the below mentioned commands to configure the java commands.

# Configure Java Alternatives
sudo update-alternatives --install "/usr/bin/java" "java" "/usr/java/openjdk/jdk-16/bin/java" 1
# Configure Javac Alternatives
sudo update-alternatives --install "/usr/bin/javac" "javac" "/usr/java/openjdk/jdk-16/bin/javac" 1
# Check version
java -version

# Output

In case JDK is already installed on your system, use the below mentioned commands to install JDK 16 with existing JDKs.

# Configure Java
sudo update-alternatives --config java

# Output
There are 3 choices for the alternative java (providing /usr/bin/java).

Selection Path Priority Status
------------------------------------------------------------
0 /usr/java/oracle/jdk-16/bin/java 3 auto mode
1 /usr/java/openjdk/jdk-15/bin/java 1 manual mode
* 2 /usr/java/oracle/jdk-16/bin/java 3 manual mode
3 /usr/java/oracle/jdk1.8.0_261/bin/java 2 manual mode

Press <enter> to keep the current choice[*], or type selection number:

# Configure Java Compiler
sudo update-alternatives --config javac

# Output
There are 3 choices for the alternative javac (providing /usr/bin/javac).

Selection Path Priority Status
------------------------------------------------------------
0 /usr/java/oracle/jdk-16/bin/javac 3 auto mode
1 /usr/java/openjdk/jdk-15/bin/javac 1 manual mode
* 2 /usr/java/oracle/jdk-16/bin/javac 3 manual mode
3 /usr/java/oracle/jdk1.8.0_261/bin/javac 2 manual mode

Press <enter> to keep the current choice[*], or type selection number:

Now check the priority number. I will configure JDK 16 using priority 3 as shown below. You can choose priority based on your requirements.

# Configure Java Alternatives
sudo update-alternatives --install "/usr/bin/java" "java" "/usr/java/openjdk/jdk-16/bin/java" 3
# Configure Java
sudo update-alternatives --config java

# Output
There are 4 choices for the alternative java (providing /usr/bin/java).

Selection Path Priority Status
------------------------------------------------------------
0 /usr/java/oracle/jdk-16/bin/java 3 auto mode
1 /usr/java/openjdk/jdk-15/bin/java 1 manual mode
2 /usr/java/openjdk/jdk-16/bin/java 3 manual mode
* 3 /usr/java/oracle/jdk-16/bin/java 3 manual mode
4 /usr/java/oracle/jdk1.8.0_261/bin/java 2 manual mode

Press <enter> to keep the current choice[*], or type selection number: 2
update-alternatives: using /usr/java/openjdk/jdk-16/bin/java to provide /usr/bin/java (java) in manual mode

# Configure Javac Alternatives
sudo update-alternatives --install "/usr/bin/javac" "javac" "/usr/java/openjdk/jdk-16/bin/javac" 3

# Configure Java Compiler
sudo update-alternatives --config javac

# Output
There are 4 choices for the alternative javac (providing /usr/bin/javac).

Selection Path Priority Status
------------------------------------------------------------
0 /usr/java/oracle/jdk-16/bin/javac 3 auto mode
1 /usr/java/openjdk/jdk-15/bin/javac 1 manual mode
2 /usr/java/openjdk/jdk-16/bin/javac 3 manual mode
* 3 /usr/java/oracle/jdk-16/bin/javac 3 manual mode
4 /usr/java/oracle/jdk1.8.0_261/bin/javac 2 manual mode

Press <enter> to keep the current choice[*], or type selection number: 2
update-alternatives: using /usr/java/openjdk/jdk-16/bin/javac to provide /usr/bin/javac (javac) in manual mode

The output of these commands is shown in Fig. 3 and Fig 4. We might need to configure active Java if it is previously installed on the system.

Install OpenJDK 16 On Ubuntu 20.04 LTS - Java Alternatives

Fig 3

Install OpenJDK 16 On Ubuntu 20.04 LTS - Java Alternatives

Fig 4

These are the basic steps required to install the most recent version of OpenJDK on Ubuntu 20.04 LTS.

Hello World

In this section, we will write our first program in Java using the nano editor.

>sudo mkdir -p /data/programs/java
>cd /data/programs/java
>sudo nano HelloWorld.java

Now write the first program in Java as shown below, save the program and exit the editor.

// Hello World
public class HelloWorld {

        // The main method
        public static void main( String[] args ) {

                // Print Hello World
                System.out.println( "Hello World !!" );
        }
}

Use the javac and java to compile and execute the program as shown below.

// Compile the program
sudo javac HelloWorld.java

// Execute the program
sudo java HelloWorld

// Program output
Hello Java !!

These are the basic steps to write, compile, and execute Java programs.

Summary

This tutorial provided all the steps to install OpenJDK 16 on Ubuntu 20.04 LTS and also provided the steps to configure it to use from the console. The last section explained the steps to write, compile, and execute the first Java program. You may submit your comments to join the discussion on installing OpenJDK 16 on Ubuntu and other Linux systems.

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