Comparing JVM language features

This branch is dedicated to compare similarties between selected JVM languages. Their constructions and features. To highlight specific only command-line is used for compilation and run.

A. Comparing the selection control mechanism, 3 JVM languages

The comparison of selection control mechanism used for change the flow of the program. The comparison is done accross a various JVM languages. Naive vehicle factory (Img.1) is considered.

1. Java - switch statement

$ java -version 
output: openjdk version "18" 2022-03-2

Used switch statement for the factory construciton is according to the JEP-420: Pattern Matching. It is required to enable preview features.

Compile Java Program:

$ javac --release 18 --enable-preview -g -classpath out -sourcepath java -d out ./java/*java

Execute Java Program:

$ java --enable-preview -cp out VehicleFactory

2. Kotlin - when statement

Kotlin language uses when statement with ability branch the program flow. The similarity to the Java switch statement is noticable.

$ kotlin -version
Kotlin version 1.6.10-release-923 (JRE 18+36-2087)

Compile Kotlin Program:

$ kotlinc ./kotlin/*.kt -include-runtime -d ./out/vehicle_factory.jar

Execute Kotlin Program:

$ kotlin -classpath ./out/vehicle_factory.jar KVehicleFactoryKt

3. Scala - match statement

Scala introduces a match pattern for controling the program flow branching. There are similarities to the Java swicht statement.

$ scala -version
Scala code runner version 2.13.8 -- Copyright 2002-2021, LAMP/EPFL and Lightbend, Inc.

Compile Scala Program:

$ scalac -d out ./scala/*.scala

Execute Scala Program

$ scala -cp out SVehicleFactory

B. Java 18 - descovering "jwebserver" possibilties JEP-408

Running simple "jwesberver" by command-line

$ jwebserver -b 0.0.0.0 -p 8880 -d <PROJECT_PATH>/http-static -o info
or
$ java -m jdk.httpserver  -b 0.0.0.0 -p 8880 -d <PROJECT_PATH>/http-static -o verbose

# execute requests 
$ curl --head http://localhost:8880
$ curl -X GET -I http://localhost:8880/get_simple_1.json
$ curl -X POST -I http://localhost:8880

Running compiled version

$ java --enable-preview -cp out WebServerSimpleMain simple | advanced
usege: 
available options: 
    - simple
    - advanced
    - <NONE> not allowed, causes an exception

Building a docker image

$ docker build -f ./docker/Dockerfile_jwebserver --no-cache -t jdk18-slim-jwebserver:latest .

Running a docker-compose

$ docker-compose down

mirage22 / jvm-language-examples