In this article we will see the usage of some common Java commands for non Java Developers.

Commands

Find Java Version

Command to get the Java version in your machine

java -version

Here is a example output from this command

openjdk version "1.8.0_252"
OpenJDK Runtime Environment (build 1.8.0_252-8u252-b09-1~18.04-b09)
OpenJDK 64-Bit Server VM (build 25.252-b09, mixed mode)

Find Java Compiler Version

Command to get the Java compiler version

javac -version

Here is a example output from this command

javac 1.8.0_252

Compile Java Code

Command to compile a java program

javac my-program.java

Run Java Code

Command to run a java program

java my-program

Change default java version

Command to change the default java version if you have multiple java installed

sudo update-alternatives --config java

Find the java home

Command to find the java home

java -XshowSettings:properties -version 2>&1 > /dev/null | grep 'java.home'

Find Max Heap Size and Max RAM

Command to find the Max Heap Size and Max RAM in a machine

java -XX:+PrintFlagsFinal -XX:MaxRAM=1g -version | grep -Ei "maxheapsize|maxram"