Java

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Java is a strongly-typed general purpose programming language. Oracle owns Java.

Java is at the heart of our digital lifestyle. It's the platform for launching careers, exploring human-to-digital interfaces, architecting the world's best applications, and unlocking innovation everywhere—from garages to global organizations. From the web site at https://www.java.com

The Java runtime should already be installed, but the Java SDK (Software Development Kit) that includes the compile and tools for program development may not be installed.

Check the version of Java runtime installed with the following command.

The following Linux command(s) verify the installed Java runtime version.

java -version

On 2019-08-04 the output was as follows.

openjdk version "1.8.0_222" OpenJDK Runtime Environment (build 1.8.0_222-b10) OpenJDK 64-Bit Server VM (build 25.222-b10, mixed mode)

The following Linux command(s) verify the installed Java SDK.

javac -version

On 2019-08-04 the output was as follows.

javac 1.8.0_222

If the Java SDK is not present, then it needs to be installed.

The following Linux command(s) install Java SDK.

sudo yum -y install java-devel

The file type of a Java program file is java.

The following Linux command(s) create/edit a hello program in the your home directory using the nano text editor.

nano ~/hello.java

Create the following program text in the editor that will output the text "Hello world"

public class hello { public hello() { System.out.print("Hello world\n"); } public static void main(String [] args) { new hello(); } }

To exit with save, remember to press Ctrl-X, then "y" (for yes) and Enter to exit.

The following Linux command(s) run the program.

javac -cp ~ hello.java java -cp ~ hello

The output should be as follows.

Hello world